I have a HG-installed heat pump, and I'm on Octopus Cosy. All I did was set a schedule with a slightly higher set point during the cheap periods, and slightly lower during the expensive period. The idea was to overheat the house a little when it's cheap, with the expectation it'll not need as much heating the rest of the time. I've also scheduled the hot water to run at 5:30am and 1pm. Currently there's something cock-eyed with the COP measurements on my controller, so I have no idea what that's doing to my efficiency, but the bills are nice and low. I have PV and a battery, so this setup only really achieves anything during the winter when my consumption is much higher than generation, and higher than the capacity of the battery.
This is the correct answer. The tracker tariff is also another option as it would likely be around the same price. These other tariffs by comparison are poor value.
Same for me. I've managed to average 14p/kWh in the last two months, saving me huge amounts on heating. Yes, you get stung during the peak at 5-7, but overall running on the weather comp the heat pump isn't stressing in those hours so it's not a big consideration
Agree, I’ve got a home storage battery as well so this further preserves me from paying peak import rates on agile. My average was 15p/kWh in December, 17p in January and 14p in February
I have just installed an ASHP with underfloor heating and a 10kwh battery. I am on the Octopus Cosy tariff with the plan being to run steady state heating (with setback temp at night) and use the battery to move most of my electricity to the cheap rate tariff. The advantage of the Cosy tariff is that I can cycle the battery twice a day (effectively allowing to shift 20 khw of electricity to the cheap rate with a 10 kWh battery. Also I have the 6 hours at the cheaper rate given by the tariff irrespective of the battery. I think I will be able to run all my heating/hot water at the. Cheap rate. Only just installed the system so will let you know if the plan works!
Always love the vids. This time the hot water comments need another look. There’s no way the marginally higher efficiency of the HP running a DHW cycle in the daytime vs night time would come anywhere near the at least double, in some cases 4x higher, electricity cost in the daytime vs off peak. It’s cheaper (and greener / lower carbon) with almost any off-peak tariff to run the DHW cycle at night, if you have a decent cylinder and low use that maybe enough HW to last all day, or if not top up a bit daytime / evening but outside 4-7pm peak times.
I agree. On Agile over the last year, the average price from 09.00 to 16.00 has been about 13p, compared with about 9p overnight. So, nearly 50% more for daytime non-peak. I would guess that the average temperature difference is not big enough that the COP is 50% better during the day.
With cheaper night rates available , batteries start to make economic sense. I’m fortunate enough to have solar PV, battery and an EV and are able to shift 95% of our grid draw to a night rate of 7.5p per kWh
The current Battery & Solar price curves mean pay back times are getting shorter. When we get to 3 years then it will make sense for lots more people. Especially if daytime electricity prices stay high relative to night time prices.
The key to load shifting for time of use tariffs is a battery. We charge our battery and heat water at cheap rate and run the heat pump from it on steady state for the r3st of the day.
Do you use solar pv for your battery or can you just connect a battery to the grid to charge it? Haven’t heard anyone mention this yet, was glad I stumbled across your comment! Our 220 year old house can’t support solar panels but we have the grant for the pump (including full installation costs) so don’t want to have to turn it down because of no solar 😢
@@richardmccann9293 can't speak for all battery systems, but I often charge mine at night on cheap rate when I know I won't generate enough solar to get through the next day in the winter. And since Feb battery installs are VAT free, even when not installed at the same time as solar panels.
Only two weeks into having a heat pump, so still experimenting. We have 6 hours cheap tariff from 11.30pm. Hot water, off for 1 hour 22.30-23.30. Run anti-legionnaire cycle daily from 3.30am. This heats 400l tank to about 56' at COP of 2.1. Lasts most of the day, and any more water needing heating has COP of 3.1. Heating is set at 21.5', with 7pm - 22.30pm at 22 (for evening relaxing). Off for an hour then 23.30pm - 5.30am set to 23' This keeps a virtual steady temperature, but shifts power usage to off peak a bit. Still tweaking heat curve downwards.
@@barriedear5990 if uoh are accessing extremely cheap rates to do it then having a greater capacity hw which would save it using expensive power later then great. If not then the nay sayers are correct.
A great conversation to be having - thank you. Throwing my own experience into the Comments mix. ASHP, in a three-year old house that I've made largely air tight. 400mm loft insulation. Reasonably long run from the pump to the cylinder/UFH, but it's well insulated. I'm on Octopus's legacy Go tariff; roughly 7.5 pence from 0030 to 0430; 40 pence for the remainder of the day. Like Michael, I try and squeeze all of my 'heat' out of the pump during those four hours. Cold snap aside, it works; 90 minutes of DHW, then two hours (more if the DHW is done) into the UFH, then a little bit extra for the radiators. The radiators can run into the peak tariff if they need a litte longer to raise the temperature upstairs. We don't wake up to a hot house - we wake up to a comfortable house. Phew! Happily, with outside air temperatures at or above 5 degrees C, the house will hold onto that heat through the day (roughly 21 degrees). As Michael does, we might see one or at worst two degrees decay by 2200. The challenge comes when the overnight temperature falls lower / below freezing, since the flow temperature drops, AND there's not enough time to add the lost heat back into the house. That's when we either put a jumper on or rely on the occasional Octopus Power Ups to run the UFH during the day (effectively for free) to put some more heat into the UFH screed. (I should add that we run 90 minutes DHW top up early afternoon if it needs it. That's at the full-fat rate). My frustration is that this is far from the best way to run the ASHP efficiently. Yet the difference in price between the two rates makes it so much cheaper to run the pump at night, that I think it worthwhile. Flow temps at the UFH manifold are around 44 degrees; the radiators are hot, but comfortable enough to touch. The DHW tank is set to 47 degrees. Essentially, the house is warm enough, and we have enough hot water, through the day, when outside temperature is at or above 5 degrees. Below that, it does get a little cooler, but it's largely manageable. I'd love to be running super-efficient steady-state heating, yet the tariff make that super-expensive for most of the day. Perhaps I should be on a different tariff, that is less cheap AND less expensive? Though I'd like to keep the Power Ups too - they're great for running the white goods. As noted, better to avoid the peaks than target the troughs?! I'd love to add panels and a battery too, but that's for another day... (Apologies for the lengthy essay!)
We have a small solar array, on the house when we bought it, a Viessmann 150a 10kw heatpump, whole house UFH and 10kW of battery storage. We run the house warm at 22c throughout, weather compensation no zoning. On Octopus intelligent tariff and pay an average of 15pkWh. Pump installed start of November 2023. Scop of 4.6 to date.
I am on V2H . 30 kWh Leaf. I am all electric now and retired. Cost of running my 3 bedroom bungalow though the winter was £65 a month. I also have solar panels.
@davelowe1977 That is great to here. May l ask what temperature do you keep your house at also what temperature is your water at. I keep my heating on 24/7 at 19°C and keep my door to the bedroom closed at night and open the window. I heat my water once a day at 50° C.
@@bobchambers6952 I have more modest temperatures. I work from home but I set the thermostat to 17° during the day for all rooms except the bedroom where I keep the window open but for really hard frosts. My water is heated on demand so it's typically one long shower worth each day that I use. That's included in the gas figure I gave above. I turn the heating off overnight.
COP changes depending on outside temperature and humidity. The last thing you should be doing is operating your heatpump only at night. Also, and it seems that Heat Geeks often forget to mention it, if the DC inverter compressor of the heat pump works at less than 100% power then the COP usually increases since the heat exchanger with the outside air is more efficient. (Google "COP vs inverter power"). Usually the optimum power is 30% of peak power.
Using a home battery to "buffer" the cheap prices and carry over the expensive times is probably the best approach. Problem is, you need a relatively large battery (my 10kWh wasn't quite enough, but worked decently) and you need to make sure your energy losses from charge/discharge and system standby aren't too large.
What about an accumulator tank? They’re commonly used with solid fuel heating such as wood pellets. Heat up a large insulated tank of water on the cheap overnight rate power then use that as a heat battery for steady state heating during throughout the day?
An issue that doesn't seem to be addressed by most of these videos is under floor heating with a thick concrete slab. I have 100mm thick slab that once warmed lasts all day or more. I also installed a trench heater for a much faster response time. This sounds like the ideal solution for stable state heating, basically the whole floor downstairs is a massive thermal mass.
I have a ground source heat pump with underfloor heating, I am on the cosy tariff. This heating season I have heated my home only on the 6 hour cheap rate, the house has retained the heat at a satisfactory level. With underfloor heating in a screeded floor a lot of heat can be stored and released slowly, the room temperature keeps rising for several hours after the heating stops, my flow temperature is between 30 to 42 degrees. We have around 6 weeks of heating left this season, but I am forecasting less electricity usage this year. However it has been quite mild this winter.
Surely the sweet spot will be steady state heating with temperature control and a house battery for use during peak periods? We're on Octopus Cosy as we're having Octopus install a heat pump in a few weeks time. We already have a 8KW house battery which we charge up during the 2 cheap periods, which allows us to run the house pretty much all day on the cheaper rate.
Our historic gas was about 14,000 kWh per year. We’ve just completed 4 months with a heat pump. Here’s the comparison of last winter with a gas boiler to this winter. Nov 22-Feb 23 gas boiler use for space heating and hot water 8206 kWh. Total £1496 Nov 23-Feb 24 electricity use by ASHP for space heating and hot water 2146 kWh. Total £89 We’ve changed multiple things, not just installed a heat pump, so I’ve had to break out the various cost savings. 3% less heating required (degree days) = £30 less cost Changing from price cap to Octopus tracker tariff gives a saving of £733 Installing Solar PV (winter months) saving of £75 Octopus Agile instead of Octopus Tracker (enabled by battery installation) gives a further saving of £244 Less saving session battery export payments of £180 Finally, heating system efficiency (ASHP with weather compensation steady state heating instead of on/off thermostats) saving of £145
Here's my real World example of Octopus Cosy for your consideration, which I've been running for 13 months: EPC B, 21hr heating, ~24°C flow mid-winter with weather compensation, DHW and appliance use only during low-rate periods. I have no idea what SCOP I'm achieving, so I'll have a look at your calculator. Cheers for the video.
What about a heat battery? Either supplied by ASHP or direct from the grid. I have been exploring the possibility of using a heat battery (eg sunamp) for home heating rather than the usual water heating. There is very little information available. A friend has air-to-air heat pumps to complement his gas boiler. His boiler was only on for a few weeks in December and January. The rest of the heating being handled by the AC.
We got on Cosy Octopus with our Daikin Altherma about 4 months ago and after lots of experimenting have settled on running heating 6-8am to take edge off (any earlier and we found it was waking us up prematurely), usually open windows to blast fresh air through the house for 30-60 mins from 10am, then heating on again 11am-4pm. Hot water is run twice a day, 4am and 2.30pm, to 45deg. I've disabled weather comp (shock horror, could never quite get it right) and basically run it dumb to charge the house with heating by setting thermostat at 28 degrees. It never reaches that but gets to 21/22 by 4pm most days around now. Flow temperature is 39 degrees. Our heating cop for Feb was 3.94. We have a wood burner that very occasionally run in evening to further charge the house but we could live without it tbh. Running heat pump during the day makes absolutely the most sense to me, outside air temp is warmer and everyone is awake. Heating runs for about 6 hours, of which prob 3 is low tariff. Hot water all done in low tariff, we run dishwasher and washing machine during low tariff (also primes with water from cylinder so doesn't use as much energy) and usually cook through peak tariff so could do more but most things go through the Ninja Foodie which uses relatively small amounts of power anyway. I think I calculated we're saving about 25% atm with these tweaks and the house is snug by day and cool to sleep by night. My wife wants a shower in morning, otherwise I could also live without morning hot water and just have evening showers, but life is too short to compromise marriage for scop
I'm a bit concerned now, because I've just had a new heating pump installed (last week) by Octopus. The worrying thing is that the design shows a flow temperature of 55°. Also, I'm on Octopus Flux, to have the option of selling solar back to the grid. This tariff only gives me a cheap period between 02:00 - 05:00, with a high period between 16:00 - 19:00. I'm thinking that I might have to move from Octopus, which would be a really hard thing to do, because they are by far the best Energy Company! Great video, thanks for the info.
By far the best way to take advantage of variable rates: batteries. Big bats cheap as chips now. Charge at night, discharge when price higher. That way keep heat pump at steady temp. (except for hot water, run that at the cheap rate).
Cosy + battery. Battery bridges the expensive time, push variable electrical use the cheap times (tumble dryer, dishwasher etc), program hot water to cheap times. Then leave my HG elite installed HP on steady state doing its thing getting 420%+ efficiency. Saves me about 20% vs using a standard tariff.
The Mitsubishi FTC6 controller comes with a means of avoiding peak price heating... But there is nothing clear in the public information but reading between the lines it seems to need a big buffer tank to store heat produced at other times. What is really needed is a simple means of controlling heat pumps so that they work at their minimum output during the peak power time in the UK 16:00 to 19:00. Setting the thermostats lower seems a crude way which might not always work. BUT as more homes move to heat pumps we may find the hump in usage is less of an issue. Turning on power showers at 9-11 kW may be a bigger issue than we know?
i have a 1300l thermal store, would a heat pump on ev octopus go with 6hrs at 7.5p, waiting for my planning ASHP, but at the moment using immersion x2 to heat my store to 70 at the cheap rate with a heat loss of my home at 6kw, keeps the underfloor heating steady at 29 for 10hrs +6hrs off peak, i had not choice as the gas boiler gave up, and ran out of logs for the thermal store. house stayed at a stable 20-21. this feb
What about smart heating, looking at decreasing outdoor temps to buffer energy before it's needed? Doing this while taking energy prices into account can result in a very efficient consumption pattern and great comfort.
Interesting. Currently I have solar PV & battery storage. I have the usual gas combi. I’ve often thought of the merits of a heat battery to absorb any excess solar & possibly use a heat pump & or solar thermal. This would primarily be for hot water and the main reason for choosing a heat battery is space. This has made me think a heat battery could have a secondary use across peak periods to maintain comfort. As you always say one size doesn’t fit all
I substantially agree with your conclusions, but in Scotland, for new builds, you basically build to near passivhaus standards. If you have underfloor heated upstairs and down, (thus the concrete slabs referenced below) AND if you have a large thermal water buffer (I've got a 1te buffer) you can run on Econ 7 using only 7 hours of direct water heating, then floor heating to get up with, then live off the buffer and thermal mass for the rest of the day. Only trouble with this is that you cannot do it with a conventional controller as you need a constant delta T across the water buffer for optimum efficiency, not weather compensation. This largely counters your argument. Also, if constant running, you have a pump running continuously (100w) whereas with timed running even this cost reduces. oh and i've got ground source pump, so warmer ground at night. so as ever "it depends"
Do you truly see ground source temperature differences during the time of day? I've got a vertical system with two ~50 meter deep boreholes, I can't say I've seen it fluctuate that much in such small time frames. I guess it's a bit different with a horizontal loop.
That was a very interesting investigation of theoretical operating strategies with various tariffs and some great tips/messages. The strategies you investigated were all based around switching the heat pump on/off for some periods of the day in response to electricity price changes. This seems quite extreme, but possibly exaggeration for the purposes of illustration. Wouldn't it be less extreme, more comfortable and more efficient to adjust the temperature setpoint throughout the day in response to price signals, rather than switching on/off? The results could be presented in similar charts, but instead of the horizontal axis displaying hours of heating per day, it could display temperature setpoint variation e.g. 0, 0.5, 1, 1.5 etc. deg C (increase during off-peak electricity periods, decrease during peak periods)
The time of use tariff is best employed charging a home battery and then powering the heat pump on the cheap stored electricity for the rest of the day. Octopus Intelligent Go for example gives six hours at 7.5p so you can avoid the peak rate entirely if your battery is big enough. Combine that with solar panels which produce a surplus in summer which you can sell back to the grid allows you to bank this surplus cash in the account so during winter your import is funded from the surplus at the cheap rate. This whole system can effectively give you zero bills over the whole year.
Hi Adam. I get so much from your vids so thank you so much. I’m sorry if I’ve missed these but I would love to see your opinion of infrared heaters and also a review of the mixergy IHP at some point if you have time and feel like others would find this interesting.
Nice video. With a time of use tariff and a heat pump it might soon be worth it to get some home battery storage as prices are dropping and Sodium-Ion becoming a real option (only from China right now). The charge/discharge losses of a battery are much smaller than the negative impact on COP and comfort by trying to excessively precharge your home with a heat pump. With current heat pumps easily reaching a COP of 4 to 5, a small 5 kWh home battery on such a tariff will deliver around 20 kWh of really cheap heating.
Is there much of a price difference when running the heat pump at night? Pretty sure you would be consuming more as the ambient outside temperature would be a lot cooler during the night than in the day, so i guess your COP would not be that great but dont know how much you would be saving?
Very interesting. My 18kW (!) twin LG ASHP’s were designed with a flow temperature on the MCS certificate of 55 degrees ! And that was with changing most of the rads. I have progressively moved towards steady state heating, running at a much lower flow rate with weather compensation turned on and an overnight setback. The house is comfortably warm 18-20 degrees al the time. Other than when it is really cold the thermal mass of the house will keep the house warm through the night and the heating doesn’t need to come on. I turn the house temp up from the overnight setback in steps so the heat pump doesn’t make a massive demand, and try to align step-up’s with cheaper time of day pricing. Daily consumption is still quite high at around 25kWh a day in winter, with really cold day peaks of 60-80kWh. Still trying to work out how to reduce this further. Agree about Cosy, my heat pump demand exceeds my battery capacity so I went for Octopus Agile which has been considerably cheaper than any other option. The battery means I can run the heat pump all day and not turn it off in peak periods. Average monthly import price is 13-18p/kWh
Have you factored domestic hot water into your calculations? I expect there's no reason not to recharge your hot water tank during off-peak. Edit: Whoops, saved that comment just as you covered that topic at the end of the premiere.
What about air-to-air, should it be left on 24 hours with indoor unit thermostats? Also, can outdoor unit be undersized as it is unlikely all indoor units will call for max heating at the same time?
I once calculated the storage we'd need to properly take advantage of an off-peak tariff, I think it worked out to be a 25,000l insulated storage tank and something silly like a 60-70kW heat pump. I think I calculated for a 50C flow temperature, heating the water to 60C and letting it drop to 50C over the day but I can't remember the exact numbers. On paper, it worked out to be a very good setup, just with some unfortunate practicality issues. Last time I looked at OVO's heat pump tariff the normal rate was more than Octopus's tariff, but it seems to have come down now so we might need to look at that again.
@@HeatGeek I meant their standard tariff for your other usage, it was 30p at the time which with out usage (Working from home) sadly made it more expensive than a flat 27p from Octopus. But now that their standard rate is 25p, heat pump plus should be a good saving for us.
Octopus's Agile tariff only got a brief mention, but I wonder if this would be a better option, if it was just used for 21 hours, avoiding the three hours, 4-7pm, when the Agile price spikes? Averaged over the last year, the Agile price for the other 21 hours of the day was 12.6p, so the Ovo HP tariff is 19% more expensive for those 21 hours. The video estimates that avoiding those three hours would increase daily usage from 102 to 120 kWh, which was rounded up to 20% increase, but is actually 17.6%. So, on those figures, Agile for 21 hours would be cheaper than steady state and though it would use more power, it would tend to be low carbon power.
Misleading video …. The ovo pricing is only available to valiant heat pump users not the majority who dont have one of those, although the ovo energy page highlights their partnership with heatgeeks if you want one of their valiant heat pumps installed 🤔
@@HeatGeek Yes, but this is a tone & style point. Just disclose the relationship. I watched this video, paused at the point you mentioned Ovo tariff. Saw the undisclosed required. Told my wife I was not surprised. Wrote my comment. Now seeing if others have called you out on it. Very happy to praise Ovo if they open this tariff to what must be 90% of UK HP installs.
@@HeatGeek Yes you really should mention this because we've got a samsung installed and it's too late for us to go down this road unless they partner with different manufacturers. waste of my time going to the OVO website to find this out
@@HeatGeek shame it got cut. Pointing out time of use with heat pump doesn't make much sense is good, but then the real options are OVO without batteries Vs time of use with batteries.
In my experience, in terms of cost, maxxing out during the Octopus Cosy half price daytime period has more than made up for the loss in efficiency. In fact I've been surprised to see not much difference in COPs compared to steady state; maybe this is due to making more use of the higher daytime temperatures? (7kW Vaillant, design temp 38C @ -2C, house with v. high thermal mass, EPC B.)
Your statement aligns with our findings.. for some reason everyone seems to miss this point of the video. Go to the graphs at the end and follow along a 35c system.. it’s much more worth kid shifting…. Then please respond here and help me understand why people keep missing this 🙏
Yes indeed, at 13:58 you make the point very clearly that time of use tariffs are worthwhile with low temp systems. I think we might miss this message because the video starts with lots of impactful 45C+ examples with Octopus Cosy, with the emphasis on hrs/day vs efficiency, and little mention of the effect of low design temps. Maybe it’s a lesson that people’s (including mine!) concentration fades towards the 2nd half of a video, especially if the 1st half carries a very strong message, and perhaps the key points need to be flagged early on. Thanks for your excellent work btw, it’s making a real difference.
I would love to see a similar calculation where you use time-of-use tariffs to charge a battery (especially an electric vehicle with bidirectional charging), while discharging continuously to run a heat pump at steady state. Would inverter losses and battery wear kill the gains?
You'd lose something like 20% of the power in AC->DC->AC conversion. Now if the heat pump could be powered by DC (Which it can, the compressor is powered with DC) it might have been more efficient and cheaper.
We had solar and house battery installed recently. At the time VAT was payable on house batteries unless installed with a solar package (however, now house batteries are VAT free). So we got 20kWh of battery in anticipation of a heat pump install, so the battery could mostly power the house and heating from just overnight cheap (currently 7.5p) electricity. If on really cold days this won't be enough, we will reserve enough battery to ensure we don't draw from the grid during peak hours. Until then, we are powering the house purely from 7.5 p electricity via the battery and our solar gets exported at 15p. During the summer we will have negative bills despite running 2 EVs!
@@Ben-gm9lo Are you on Octopus? Which tariff? Only Octopus Flexible gives 15p upload, but no night tariff. Unless it's changed, we're on Octopus Go, 4 hours at 9p and upload 8p. Thanks
Do you take into account the cost of your installation? A bigger Heat pump costs more, is usually less efficient and doesn't turning off/on your heat pump that much, hurts its lifetime as well? I see heat pumps with continues runs of over 10 days in winter. When you turn them off when tariffs are high, it will have an impact on its lifetime, I would think?
It’s such a shame that our energy providers don’t do the same as America for solar I.e what ever unit you give them you get back rather than buying at peanuts and selling back more expensive
Your graphs show:- Heating 24 hrs is cheapest not intermittent. Fur 24 hour heating the difference in cost between 35 and 50 degrees is less than £100 per year cost for the typical house. So the ROI in moving from 50 to 35 degrees is very long. Best bang for your buck seems to just get a system cheap for 50 degrees that will cope? Happy to be corrected... PS.. This is the Octopus business model I believe
i think this is slightly misleading because we don't spec the radiator for constant use. the duty cycle for them even at the MCS outside temp is only meant to be about 50%? you would never be able to heat the house if it was 100!
I’m on OctopusGo (cheap 0030 to 0430) with a solar & battery Heating is on set back from 10pm to 2am. Battery stops charging at 4.30am . On coldest of days we manage to get to 4pm before needing to draw from the grid. Our heating cost for January has gone from £235 on gas last year to £75 on electric with the ASHP
That's good to hear as I'm about to get a heat pump and run from batteries. I recently switched to Intelligent Octopus Go which gives 7.5p from 23:30 to 05:30 so would give you an extra 2 hrs.
The panel/battery combination is a revelation. When I bought it originally I saw the battery as a means to store excess generation. However, since export rates have gone up and cheap overnight electricity we’ve made significant savings Electric car is arriving soon (seems like I’ve been waiting for ages). As soon as it’s plugged in I’m switching to Intelligent. I’ll swap the timing for battery charge to end at 0530, that way the car won’t charge from the house battery
@gruff2001 yes, the off peak side of batteries is a real winner. As a point, you can set the "when I need the car ready" time on Intelligent Octopus Go to 05:30 to make sure the car doesn't charge from the home battery as well
@@mikeroberts8412 thx for that. Just had the phone call from dealer - car is ready for collection next week. That’ll be good bye to all fossil fuels in our household
I work in green energy. I worry this video is music to the gas industry's ears. The idea of heat pumps running 4-7pm will fill the electricity networks with dread. This video is quite simplistic. The fact is that all heat pumps and emitters are oversized once you're above - 2C. COP is also far more dependent on outdoor temperature than flow temperature. There's a real argument for dynamic flow temperature control, with higher flow temperatures mid-afternoon when the air is warmest and using excess heat to ride through the evening electricity peak. The basic problem is that controls are still rubbish (I've got an Ecodan - so this is particularly true). All heat pumps should be predictive of weather conditions, be using the house's thermal mass as buffer and calculate the cheapest way of keeping your house within a defined temperature range with smart tarriffs. SCOPs might improve that way, but cost, not SCOP, should be the target. Your advice is probably correct for houses today, but it's not sustainable for a cheap, decarbonised grid. I plan on programming my way through this with Home Assistant, but I'm not the average consumer. Lots still to do!
With setback overnight, wouldn't that normally be the same thing as turning off the AHSP most of the night? Unless it is really cold outside or the house has unusually high heat loss, the temperature will only drop to the set back temperature at say 5am or 6am. So, the ASHP will be off overnight. So setback would mean not steady state for 24 hours except on the coldest days. Is that right, or am I overlooking something?
@@HeatGeek Sorry, are you saying that with a 2 degree set back the ASHP would only be off for an hour? That is, it would take an hour for the house to lose 2C on a cold night? So the ASHP would be operating 23 hours steady state? If that's what you meant, I'm sceptical. I did some monitoring overnight on 27 Jan. It was 2C outside at midnight and it fell to 1C by 6am. Over those 6 hours my rooms fell by between 1C and 2.6C. On average, less than 2C. I think for my house a 2 degree setback would mean the ASHP would be off the whole night except on the handful of nights when the outside temperature is well below zero.
This is where thermal stores solves most of these problems and a 500l can store 25kwh and you could double this. Heat pump using electricity for 6 hours that is 4 times cheaper at may be half the COP when it would not be used due to setback at night Other benefits are longer heat pump run times and quicker response plus stops overheating due to solar gain Please do a show on this!
@@HeatGeek agree. I have a biomass (Pellet) boiler which is quite cheap in use, heats up our 250 litre thermal store for heating and hot water, I believe these need to be separate. The system is oversized 13kWh heating/water 3kWh room heating and not very controllable which makes the house too dry and gives me dry/sore throat. The house is 144 sq meter, underfloor heating, radiators not used upstairs and an EPC of 100. I would love to have a heat pump installed but apparently we can’t get the BUS grant to help.
The information about the heating requirements for underfloor heating is incorrect. I heat my home in Denmark at 35-40 degrees for 3-5 hours and the thermal mass of the building keeps us warm 21C until next day… our floors are very well insulated here 3/400mm of insulation under a 10cm concrete floor. So warming a floor to 120 degrees is way out!!!
See i cant work out if its worth it for my mum who has a heat pump, her controls are pretty dumb (council install) and she likes the heating on all the time but a lower temperature at night. It has no heat compensation and by looking at the graph nit a very efficient hot water tank as it tops up the temperature quite regularly. She has a cop in the 3s so not too bad but i just dont really kniw where to start to improve its efficiency and cost to run.
The system is possibly set for "Reheat" on the hot water. That could be changed. Reprogramming the controller could work wonders. Our installer normally configures for set flow temperature (55') like that. I reprogrammed the system for weather compensation and operation that sounds similar to what your mum likes. We see flow temperatures below 45' and much better efficiency.
@@garrywhiting8398 thanks for the reply. I can't see any form of weather compensation be it on the terrible controller or the clunky app it's really annoying. Also no option to have seperate temperature for flow and water it just does both at the same temperature so I'm a little bit wary to bring it down because of legonella. My mum doesn't want the rads cooler but if I can work out a way to do it separately I will do it and not say just fora few days and see how it affects the cop. She has the water on constantly as she has a pain condition she likes to have regular baths as and when. It seems like the tank drops temperature soo quickly.wh en compared to my setup the water gets to temp and is still holding near enough the same temperature by the evening and I heat first thing in morning. It just seems really bad for a tank that's a couple years old. I also find it quite hard to find much info on the mitsubishi system. I also believe the system. Is well oversized for one bed bungalow aswell so not sure how that affects efficiency. My mind would suggest it would be better as the system wouldnt have to work so hard to get the job done. At the moment her bills aren't far behind mine and I heat my house 24/7 3 bed with 6 of us so something isn't adding up.
As Octopus Agile tariff is very cheap 4 hours in a day, how any hours in a day is it cheaper powering a HP with a sensible average COP of 3.5, what is the amount of storage and excess power would you need to use?
I have been keen on a heat pump. However, this video has really put me off. At present, I think the infrared panels will be better as they heat the room and its mass rather than the air.
Don't let it put you off. We went from storage heaters to heat pump. We are steady state but we have a daytime temp of 18 and night of 16. At the moment we're about £4 per day we're on eco 7 so hot water done during night and has a setback level of 40degrees during the day which we've never actually got down to.
@@AbbyB650 thanks. I'm really waiting for the Octopus Cosy Heat pumps as these look to give a better bang for buck over the current range of heat pumps. Considering we are likely to need colling, I am also looking at air to air as this may be a better solution, year around when paired with infrared in bathrooms etc...
@@davidgates3498 the Octopus unit is unlikely to run at high efficiencies from what we have seen of it. The company are likely to cover this by offering specific tariffs to adjust the costs. Daikin produce reversible versions of the Altherma to provide cooling. Personal comfort and efficiency is different between A2A and A2W. Many A2W users compare their comfort as being similar to (average) summer time ie "it's just comfortable. You don't really notice it cold or hot." Get onto the HG map and talk to one (or more) of your local Geeks, and possibly see an existing installation.
@@garrywhiting8398 thanks, time will tell about the Cosy. They are very slow at releasing any info on the product, especially as it was launched with such fanfare. Re the Heatgeek video, I love these videos, great info. This one really made me think about the instal. I really, really don't want any more or bigger radiators. Seeing as having these is quoted as being key to a necessity the. I think I'm really going to consider and extra powerwall and something else for heating like Infrared.
Cosy only really makes sense when you setback during peak and shift hot water to the cheap periods. Whether you can save extra money via slightly boosting heating during cheap periods depends on your home insulation, lifestyle and installation.
Why do my figures come out so differently? ruclips.net/video/6gtg6AZts1E/видео.html Octopus tracker/Agile FTW for the typical heat pump home witbout battery storage.
I think the assumptions were the efficiency losses were based on outdoor design temp (e.g. -2C), whereas most of the year you don't need a larger unit or larger emitters and wouldn't drop down to .6 COP 😅 Averaged 12p/kWh for February on Agile so already beating OVO pricing and I don't have a battery to carry me through peaks.
Is this video slightly disingenuous? At the time of writing this comment 17/3/24, Ovo Heat Pump tariff is only available to Vaillant HPs or supplied or installed HPs. This is not clear in the video, unless I missed it. I did wonder why the first 6 minutes was spent exploring a pretty ludicrous usage scenario with Octopus Cosy. This kind of content that appears to be customer centric, but is really a thinly veiled advert, leaves a bit of a bad taste. How can I trust the things you say in other videos?
There’s a few using cosy in the 6 hours and if you have a low temperature system it’s totally acceptable and incredibly cheap! Ovo won’t only be offering this with vailant for long I would t think.. they want more customers
@@HeatGeek I don’t think enough credit is given to the potential benefit of flexi pricing options. Yes at near freezing (-2oC) you aren’t going to have room to play tunes with prices (and zoning for that matter), but on warmer days or times when the price is even cheaper on flexi tarrif there is more room to do this.
@@fiable262626 so you don’t disagree, you think enough emphasis is put on part load shifting. There’s less energy and money to be saved there so could come out in the wash. Regardless we’re talking about small somes money. The money doesn’t reflect how important it may be to do though
I have a HG-installed heat pump, and I'm on Octopus Cosy. All I did was set a schedule with a slightly higher set point during the cheap periods, and slightly lower during the expensive period. The idea was to overheat the house a little when it's cheap, with the expectation it'll not need as much heating the rest of the time. I've also scheduled the hot water to run at 5:30am and 1pm. Currently there's something cock-eyed with the COP measurements on my controller, so I have no idea what that's doing to my efficiency, but the bills are nice and low. I have PV and a battery, so this setup only really achieves anything during the winter when my consumption is much higher than generation, and higher than the capacity of the battery.
Yes that’s it.. ide say that would be the same as looking at around 23hours heating
Swiched from price cap to agile. Steady state with 1 degree setback for the peak. Averaging around 17p kwh. Bill are right down.
This is the correct answer. The tracker tariff is also another option as it would likely be around the same price. These other tariffs by comparison are poor value.
Same for me. I've managed to average 14p/kWh in the last two months, saving me huge amounts on heating. Yes, you get stung during the peak at 5-7, but overall running on the weather comp the heat pump isn't stressing in those hours so it's not a big consideration
@mattsgreen yes it's great. And the peak is only a fraction over the price cap. Great while wholesale is stable.
Agree, I’ve got a home storage battery as well so this further preserves me from paying peak import rates on agile. My average was 15p/kWh in December, 17p in January and 14p in February
Me too. Cheap as chips though it might rise slightly with gas prices rising.
I have just installed an ASHP with underfloor heating and a 10kwh battery. I am on the Octopus Cosy tariff with the plan being to run steady state heating (with setback temp at night) and use the battery to move most of my electricity to the cheap rate tariff. The advantage of the Cosy tariff is that I can cycle the battery twice a day (effectively allowing to shift 20 khw of electricity to the cheap rate with a 10 kWh battery. Also I have the 6 hours at the cheaper rate given by the tariff irrespective of the battery. I think I will be able to run all my heating/hot water at the. Cheap rate. Only just installed the system so will let you know if the plan works!
Always love the vids. This time the hot water comments need another look. There’s no way the marginally higher efficiency of the HP running a DHW cycle in the daytime vs night time would come anywhere near the at least double, in some cases 4x higher, electricity cost in the daytime vs off peak. It’s cheaper (and greener / lower carbon) with almost any off-peak tariff to run the DHW cycle at night, if you have a decent cylinder and low use that maybe enough HW to last all day, or if not top up a bit daytime / evening but outside 4-7pm peak times.
I agree. On Agile over the last year, the average price from 09.00 to 16.00 has been about 13p, compared with about 9p overnight. So, nearly 50% more for daytime non-peak. I would guess that the average temperature difference is not big enough that the COP is 50% better during the day.
With cheaper night rates available , batteries start to make economic sense. I’m fortunate enough to have solar PV, battery and an EV and are able to shift 95% of our grid draw to a night rate of 7.5p per kWh
You will never see a return
@@delboy6384Not correct at all. Payback is currently showing to be 6 years.
The current Battery & Solar price curves mean pay back times are getting shorter. When we get to 3 years then it will make sense for lots more people. Especially if daytime electricity prices stay high relative to night time prices.
The key to load shifting for time of use tariffs is a battery. We charge our battery and heat water at cheap rate and run the heat pump from it on steady state for the r3st of the day.
Do you use solar pv for your battery or can you just connect a battery to the grid to charge it? Haven’t heard anyone mention this yet, was glad I stumbled across your comment! Our 220 year old house can’t support solar panels but we have the grant for the pump (including full installation costs) so don’t want to have to turn it down because of no solar 😢
@@richardmccann9293 can't speak for all battery systems, but I often charge mine at night on cheap rate when I know I won't generate enough solar to get through the next day in the winter. And since Feb battery installs are VAT free, even when not installed at the same time as solar panels.
Only two weeks into having a heat pump, so still experimenting. We have 6 hours cheap tariff from 11.30pm. Hot water, off for 1 hour 22.30-23.30. Run anti-legionnaire cycle daily from 3.30am. This heats 400l tank to about 56' at COP of 2.1. Lasts most of the day, and any more water needing heating has COP of 3.1. Heating is set at 21.5', with 7pm - 22.30pm at 22 (for evening relaxing). Off for an hour then 23.30pm - 5.30am set to 23' This keeps a virtual steady temperature, but shifts power usage to off peak a bit. Still tweaking heat curve downwards.
Please watch our video on legionares and hot water store temperature. A daily anti legionella is not required
Just doing it as a way to utilise the cheap rate. @@HeatGeek
Christ I run a legionella cycle once a week and that's probably overkill. Switch it off!!!
@@edwardbyard6540 Getting a full tank of hotter water for a third of the cost. How is that overkill?
@@barriedear5990 if uoh are accessing extremely cheap rates to do it then having a greater capacity hw which would save it using expensive power later then great. If not then the nay sayers are correct.
I’m on octopus agile. Saving an absolute fortune compared with their flexible standard tariff.
Same here I’ve averaged 16p KWh since September.
Same here, I’ve halved my bill
A great conversation to be having - thank you.
Throwing my own experience into the Comments mix. ASHP, in a three-year old house that I've made largely air tight. 400mm loft insulation. Reasonably long run from the pump to the cylinder/UFH, but it's well insulated.
I'm on Octopus's legacy Go tariff; roughly 7.5 pence from 0030 to 0430; 40 pence for the remainder of the day. Like Michael, I try and squeeze all of my 'heat' out of the pump during those four hours. Cold snap aside, it works; 90 minutes of DHW, then two hours (more if the DHW is done) into the UFH, then a little bit extra for the radiators. The radiators can run into the peak tariff if they need a litte longer to raise the temperature upstairs. We don't wake up to a hot house - we wake up to a comfortable house. Phew!
Happily, with outside air temperatures at or above 5 degrees C, the house will hold onto that heat through the day (roughly 21 degrees). As Michael does, we might see one or at worst two degrees decay by 2200. The challenge comes when the overnight temperature falls lower / below freezing, since the flow temperature drops, AND there's not enough time to add the lost heat back into the house. That's when we either put a jumper on or rely on the occasional Octopus Power Ups to run the UFH during the day (effectively for free) to put some more heat into the UFH screed. (I should add that we run 90 minutes DHW top up early afternoon if it needs it. That's at the full-fat rate).
My frustration is that this is far from the best way to run the ASHP efficiently. Yet the difference in price between the two rates makes it so much cheaper to run the pump at night, that I think it worthwhile. Flow temps at the UFH manifold are around 44 degrees; the radiators are hot, but comfortable enough to touch. The DHW tank is set to 47 degrees.
Essentially, the house is warm enough, and we have enough hot water, through the day, when outside temperature is at or above 5 degrees. Below that, it does get a little cooler, but it's largely manageable.
I'd love to be running super-efficient steady-state heating, yet the tariff make that super-expensive for most of the day. Perhaps I should be on a different tariff, that is less cheap AND less expensive? Though I'd like to keep the Power Ups too - they're great for running the white goods.
As noted, better to avoid the peaks than target the troughs?! I'd love to add panels and a battery too, but that's for another day... (Apologies for the lengthy essay!)
We have a small solar array, on the house when we bought it, a Viessmann 150a 10kw heatpump, whole house UFH and 10kW of battery storage. We run the house warm at 22c throughout, weather compensation no zoning. On Octopus intelligent tariff and pay an average of 15pkWh. Pump installed start of November 2023. Scop of 4.6 to date.
I am on V2H . 30 kWh Leaf. I am all electric now and retired. Cost of running my 3 bedroom bungalow though the winter was £65 a month. I also have solar panels.
3 bed house here. £33 - £34 month heating and hot water during the coldest month using a 24 year old gas combi boiler.
@davelowe1977 That is great to here. May l ask what temperature do you keep your house at also what temperature is your water at. I keep my heating on 24/7 at 19°C and keep my door to the bedroom closed at night and open the window. I heat my water once a day at 50° C.
@@bobchambers6952 I have more modest temperatures. I work from home but I set the thermostat to 17° during the day for all rooms except the bedroom where I keep the window open but for really hard frosts. My water is heated on demand so it's typically one long shower worth each day that I use. That's included in the gas figure I gave above. I turn the heating off overnight.
Well done .It's all about keeping the cost down and it's good for the environment.
COP changes depending on outside temperature and humidity. The last thing you should be doing is operating your heatpump only at night.
Also, and it seems that Heat Geeks often forget to mention it, if the DC inverter compressor of the heat pump works at less than 100% power then the COP usually increases since the heat exchanger with the outside air is more efficient. (Google "COP vs inverter power"). Usually the optimum power is 30% of peak power.
Using a home battery to "buffer" the cheap prices and carry over the expensive times is probably the best approach. Problem is, you need a relatively large battery (my 10kWh wasn't quite enough, but worked decently) and you need to make sure your energy losses from charge/discharge and system standby aren't too large.
What about an accumulator tank? They’re commonly used with solid fuel heating such as wood pellets. Heat up a large insulated tank of water on the cheap overnight rate power then use that as a heat battery for steady state heating during throughout the day?
The ere isn’t enough volume to bother using them and they require higher temps still so lower efficiency again
Love the videos , I got a hybrid .....solar panel and heat pump ... I keep my water at touchable heat think it's 40 on my boiler
An issue that doesn't seem to be addressed by most of these videos is under floor heating with a thick concrete slab. I have 100mm thick slab that once warmed lasts all day or more. I also installed a trench heater for a much faster response time. This sounds like the ideal solution for stable state heating, basically the whole floor downstairs is a massive thermal mass.
I have a ground source heat pump with underfloor heating, I am on the cosy tariff. This heating season I have heated my home only on the 6 hour cheap rate, the house has retained the heat at a satisfactory level. With underfloor heating in a screeded floor a lot of heat can be stored and released slowly, the room temperature keeps rising for several hours after the heating stops, my flow temperature is between 30 to 42 degrees. We have around 6 weeks of heating left this season, but I am forecasting less electricity usage this year. However it has been quite mild this winter.
I have a Samsung ashp, and 24kwh of batteries without solar, at the moment, on eon next drive and my highest average price per kw was 0.18p in winter
Surely the sweet spot will be steady state heating with temperature control and a house battery for use during peak periods? We're on Octopus Cosy as we're having Octopus install a heat pump in a few weeks time. We already have a 8KW house battery which we charge up during the 2 cheap periods, which allows us to run the house pretty much all day on the cheaper rate.
Very helpful with a great explanation. It’s great to hear other people saying what I have training for the last 18 years at Mitsubishi Electric.
Our historic gas was about 14,000 kWh per year.
We’ve just completed 4 months with a heat pump.
Here’s the comparison of last winter with a gas boiler to this winter.
Nov 22-Feb 23 gas boiler use for space heating and hot water 8206 kWh. Total £1496
Nov 23-Feb 24 electricity use by ASHP for space heating and hot water 2146 kWh. Total £89
We’ve changed multiple things, not just installed a heat pump, so I’ve had to break out the various cost savings.
3% less heating required (degree days) = £30 less cost
Changing from price cap to
Octopus tracker tariff gives a saving of £733
Installing Solar PV (winter months) saving of £75
Octopus Agile instead of Octopus Tracker (enabled by battery installation) gives a further saving of £244
Less saving session battery export payments of £180
Finally, heating system efficiency (ASHP with weather compensation steady state heating instead of on/off thermostats) saving of £145
Here's my real World example of Octopus Cosy for your consideration, which I've been running for 13 months: EPC B, 21hr heating, ~24°C flow mid-winter with weather compensation, DHW and appliance use only during low-rate periods. I have no idea what SCOP I'm achieving, so I'll have a look at your calculator. Cheers for the video.
What about a heat battery? Either supplied by ASHP or direct from the grid. I have been exploring the possibility of using a heat battery (eg sunamp) for home heating rather than the usual water heating. There is very little information available. A friend has air-to-air heat pumps to complement his gas boiler. His boiler was only on for a few weeks in December and January. The rest of the heating being handled by the AC.
We got on Cosy Octopus with our Daikin Altherma about 4 months ago and after lots of experimenting have settled on running heating 6-8am to take edge off (any earlier and we found it was waking us up prematurely), usually open windows to blast fresh air through the house for 30-60 mins from 10am, then heating on again 11am-4pm. Hot water is run twice a day, 4am and 2.30pm, to 45deg. I've disabled weather comp (shock horror, could never quite get it right) and basically run it dumb to charge the house with heating by setting thermostat at 28 degrees. It never reaches that but gets to 21/22 by 4pm most days around now. Flow temperature is 39 degrees. Our heating cop for Feb was 3.94. We have a wood burner that very occasionally run in evening to further charge the house but we could live without it tbh. Running heat pump during the day makes absolutely the most sense to me, outside air temp is warmer and everyone is awake. Heating runs for about 6 hours, of which prob 3 is low tariff. Hot water all done in low tariff, we run dishwasher and washing machine during low tariff (also primes with water from cylinder so doesn't use as much energy) and usually cook through peak tariff so could do more but most things go through the Ninja Foodie which uses relatively small amounts of power anyway. I think I calculated we're saving about 25% atm with these tweaks and the house is snug by day and cool to sleep by night. My wife wants a shower in morning, otherwise I could also live without morning hot water and just have evening showers, but life is too short to compromise marriage for scop
I'm a bit concerned now, because I've just had a new heating pump installed (last week) by Octopus. The worrying thing is that the design shows a flow temperature of 55°. Also, I'm on Octopus Flux, to have the option of selling solar back to the grid. This tariff only gives me a cheap period between 02:00 - 05:00, with a high period between 16:00 - 19:00. I'm thinking that I might have to move from Octopus, which would be a really hard thing to do, because they are by far the best Energy Company! Great video, thanks for the info.
With an inverter and battery you can charge it up at the cheap rate and then run your heatpump off your battery. My average rate on Agile is quite low
By far the best way to take advantage of variable rates: batteries. Big bats cheap as chips now. Charge at night, discharge when price higher. That way keep heat pump at steady temp. (except for hot water, run that at the cheap rate).
Cosy + battery. Battery bridges the expensive time, push variable electrical use the cheap times (tumble dryer, dishwasher etc), program hot water to cheap times. Then leave my HG elite installed HP on steady state doing its thing getting 420%+ efficiency. Saves me about 20% vs using a standard tariff.
With 3.5p per kWh heating costs on ovo, would you bother!?
Put in a bigger tank and heat the tank during the night, and run your radiators/underfloor heating as steady state temp for the house.
The Mitsubishi FTC6 controller comes with a means of avoiding peak price heating... But there is nothing clear in the public information but reading between the lines it seems to need a big buffer tank to store heat produced at other times. What is really needed is a simple means of controlling heat pumps so that they work at their minimum output during the peak power time in the UK 16:00 to 19:00. Setting the thermostats lower seems a crude way which might not always work. BUT as more homes move to heat pumps we may find the hump in usage is less of an issue. Turning on power showers at 9-11 kW may be a bigger issue than we know?
i have a 1300l thermal store, would a heat pump on ev octopus go with 6hrs at 7.5p,
waiting for my planning ASHP, but at the moment using immersion x2 to heat my store to 70 at the cheap rate with a heat loss of my home at 6kw, keeps the underfloor heating steady at 29 for 10hrs +6hrs off peak,
i had not choice as the gas boiler gave up, and ran out of logs for the thermal store.
house stayed at a stable 20-21. this feb
What about smart heating, looking at decreasing outdoor temps to buffer energy before it's needed? Doing this while taking energy prices into account can result in a very efficient consumption pattern and great comfort.
Interesting. Currently I have solar PV & battery storage. I have the usual gas combi. I’ve often thought of the merits of a heat battery to absorb any excess solar & possibly use a heat pump & or solar thermal. This would primarily be for hot water and the main reason for choosing a heat battery is space. This has made me think a heat battery could have a secondary use across peak periods to maintain comfort. As you always say one size doesn’t fit all
I substantially agree with your conclusions, but in Scotland, for new builds, you basically build to near passivhaus standards. If you have underfloor heated upstairs and down, (thus the concrete slabs referenced below) AND if you have a large thermal water buffer (I've got a 1te buffer) you can run on Econ 7 using only 7 hours of direct water heating, then floor heating to get up with, then live off the buffer and thermal mass for the rest of the day. Only trouble with this is that you cannot do it with a conventional controller as you need a constant delta T across the water buffer for optimum efficiency, not weather compensation. This largely counters your argument. Also, if constant running, you have a pump running continuously (100w) whereas with timed running even this cost reduces. oh and i've got ground source pump, so warmer ground at night. so as ever "it depends"
Do you truly see ground source temperature differences during the time of day? I've got a vertical system with two ~50 meter deep boreholes, I can't say I've seen it fluctuate that much in such small time frames. I guess it's a bit different with a horizontal loop.
That was a very interesting investigation of theoretical operating strategies with various tariffs and some great tips/messages.
The strategies you investigated were all based around switching the heat pump on/off for some periods of the day in response to electricity price changes. This seems quite extreme, but possibly exaggeration for the purposes of illustration.
Wouldn't it be less extreme, more comfortable and more efficient to adjust the temperature setpoint throughout the day in response to price signals, rather than switching on/off? The results could be presented in similar charts, but instead of the horizontal axis displaying hours of heating per day, it could display temperature setpoint variation e.g. 0, 0.5, 1, 1.5 etc. deg C (increase during off-peak electricity periods, decrease during peak periods)
It was illustrative yes.
The time of use tariff is best employed charging a home battery and then powering the heat pump on the cheap stored electricity for the rest of the day. Octopus Intelligent Go for example gives six hours at 7.5p so you can avoid the peak rate entirely if your battery is big enough. Combine that with solar panels which produce a surplus in summer which you can sell back to the grid allows you to bank this surplus cash in the account so during winter your import is funded from the surplus at the cheap rate. This whole system can effectively give you zero bills over the whole year.
Hi Adam. I get so much from your vids so thank you so much. I’m sorry if I’ve missed these but I would love to see your opinion of infrared heaters and also a review of the mixergy IHP at some point if you have time and feel like others would find this interesting.
Nice video. With a time of use tariff and a heat pump it might soon be worth it to get some home battery storage as prices are dropping and Sodium-Ion becoming a real option (only from China right now).
The charge/discharge losses of a battery are much smaller than the negative impact on COP and comfort by trying to excessively precharge your home with a heat pump.
With current heat pumps easily reaching a COP of 4 to 5, a small 5 kWh home battery on such a tariff will deliver around 20 kWh of really cheap heating.
Particularly as battery-only (no solar) installation is VAT-free now.
Is there much of a price difference when running the heat pump at night? Pretty sure you would be consuming more as the ambient outside temperature would be a lot cooler during the night than in the day, so i guess your COP would not be that great but dont know how much you would be saving?
Very interesting. My 18kW (!) twin LG ASHP’s were designed with a flow temperature on the MCS certificate of 55 degrees ! And that was with changing most of the rads.
I have progressively moved towards steady state heating, running at a much lower flow rate with weather compensation turned on and an overnight setback.
The house is comfortably warm 18-20 degrees al the time. Other than when it is really cold the thermal mass of the house will keep the house warm through the night and the heating doesn’t need to come on.
I turn the house temp up from the overnight setback in steps so the heat pump doesn’t make a massive demand, and try to align step-up’s with cheaper time of day pricing. Daily consumption is still quite high at around 25kWh a day in winter, with really cold day peaks of 60-80kWh. Still trying to work out how to reduce this further.
Agree about Cosy, my heat pump demand exceeds my battery capacity so I went for Octopus Agile which has been considerably cheaper than any other option. The battery means I can run the heat pump all day and not turn it off in peak periods. Average monthly import price is 13-18p/kWh
Have you factored domestic hot water into your calculations? I expect there's no reason not to recharge your hot water tank during off-peak. Edit: Whoops, saved that comment just as you covered that topic at the end of the premiere.
COP at night is lower than the day. This should be taken into account.
What about air-to-air, should it be left on 24 hours with indoor unit thermostats? Also, can outdoor unit be undersized as it is unlikely all indoor units will call for max heating at the same time?
Surely there is a drastic difference if you have solar and battery?
Yes for the 5% of uk homes with solar panels they have an additional benefit. But for the sake of keeping things simple that will have its own episode
I once calculated the storage we'd need to properly take advantage of an off-peak tariff, I think it worked out to be a 25,000l insulated storage tank and something silly like a 60-70kW heat pump. I think I calculated for a 50C flow temperature, heating the water to 60C and letting it drop to 50C over the day but I can't remember the exact numbers. On paper, it worked out to be a very good setup, just with some unfortunate practicality issues.
Last time I looked at OVO's heat pump tariff the normal rate was more than Octopus's tariff, but it seems to have come down now so we might need to look at that again.
Heat pump plus has only ever been 15p
@@HeatGeek I meant their standard tariff for your other usage, it was 30p at the time which with out usage (Working from home) sadly made it more expensive than a flat 27p from Octopus. But now that their standard rate is 25p, heat pump plus should be a good saving for us.
Octopus's Agile tariff only got a brief mention, but I wonder if this would be a better option, if it was just used for 21 hours, avoiding the three hours, 4-7pm, when the Agile price spikes?
Averaged over the last year, the Agile price for the other 21 hours of the day was 12.6p, so the Ovo HP tariff is 19% more expensive for those 21 hours. The video estimates that avoiding those three hours would increase daily usage from 102 to 120 kWh, which was rounded up to 20% increase, but is actually 17.6%. So, on those figures, Agile for 21 hours would be cheaper than steady state and though it would use more power, it would tend to be low carbon power.
Yes that was a bit more complicated to work out but we’re building a calculator
Misleading video …. The ovo pricing is only available to valiant heat pump users not the majority who dont have one of those, although the ovo energy page highlights their partnership with heatgeeks if you want one of their valiant heat pumps installed 🤔
At the moment
@@HeatGeek Yes, but this is a tone & style point. Just disclose the relationship. I watched this video, paused at the point you mentioned Ovo tariff. Saw the undisclosed required. Told my wife I was not surprised. Wrote my comment. Now seeing if others have called you out on it. Very happy to praise Ovo if they open this tariff to what must be 90% of UK HP installs.
@@HeatGeek Yes you really should mention this because we've got a samsung installed and it's too late for us to go down this road unless they partner with different manufacturers. waste of my time going to the OVO website to find this out
Have you considered the same video with battery storage system
We recorded it and had to chop it due to time and complexity.
@@HeatGeek shame it got cut. Pointing out time of use with heat pump doesn't make much sense is good, but then the real options are OVO without batteries Vs time of use with batteries.
EDF have a similar tarrif to octopus cosy home but without the peak!
I can’t see the link to the spreadsheet in the description. I have tried all of the links, but none take me to a spreadsheet.
Read the description please
how do I see if my heat pump is efficient? I have a Mitsubishi ecodan
In my experience, in terms of cost, maxxing out during the Octopus Cosy half price daytime period has more than made up for the loss in efficiency. In fact I've been surprised to see not much difference in COPs compared to steady state; maybe this is due to making more use of the higher daytime temperatures? (7kW Vaillant, design temp 38C @ -2C, house with v. high thermal mass, EPC B.)
Your statement aligns with our findings.. for some reason everyone seems to miss this point of the video. Go to the graphs at the end and follow along a 35c system.. it’s much more worth kid shifting…. Then please respond here and help me understand why people keep missing this 🙏
Yes indeed, at 13:58 you make the point very clearly that time of use tariffs are worthwhile with low temp systems. I think we might miss this message because the video starts with lots of impactful 45C+ examples with Octopus Cosy, with the emphasis on hrs/day vs efficiency, and little mention of the effect of low design temps. Maybe it’s a lesson that people’s (including mine!) concentration fades towards the 2nd half of a video, especially if the 1st half carries a very strong message, and perhaps the key points need to be flagged early on.
Thanks for your excellent work btw, it’s making a real difference.
I would love to see a similar calculation where you use time-of-use tariffs to charge a battery (especially an electric vehicle with bidirectional charging), while discharging continuously to run a heat pump at steady state. Would inverter losses and battery wear kill the gains?
You'd lose something like 20% of the power in AC->DC->AC conversion. Now if the heat pump could be powered by DC (Which it can, the compressor is powered with DC) it might have been more efficient and cheaper.
Yes I made this too but the video got too huge!!
Works for me. With a 9.5 kWh battery and a heat pump on Cosy, I'm averaging 17 p/kWh for imported power.
We had solar and house battery installed recently. At the time VAT was payable on house batteries unless installed with a solar package (however, now house batteries are VAT free). So we got 20kWh of battery in anticipation of a heat pump install, so the battery could mostly power the house and heating from just overnight cheap (currently 7.5p) electricity. If on really cold days this won't be enough, we will reserve enough battery to ensure we don't draw from the grid during peak hours.
Until then, we are powering the house purely from 7.5 p electricity via the battery and our solar gets exported at 15p. During the summer we will have negative bills despite running 2 EVs!
@@Ben-gm9lo Are you on Octopus? Which tariff? Only Octopus Flexible gives 15p upload, but no night tariff. Unless it's changed, we're on Octopus Go, 4 hours at 9p and upload 8p. Thanks
What happens when you include batteries in the equation?
Do you take into account the cost of your installation?
A bigger Heat pump costs more, is usually less efficient and doesn't turning off/on your heat pump that much, hurts its lifetime as well?
I see heat pumps with continues runs of over 10 days in winter. When you turn them off when tariffs are high, it will have an impact on its lifetime, I would think?
No because in reality you would size it more correctly and run it more often in winter
@@HeatGeek when you use stable state heating, sure.
But load-shifting, does has a negative impact on your heat pump, I would think?
Loved the Puns! Thank you for the Video!
It’s such a shame that our energy providers don’t do the same as America for solar I.e what ever unit you give them you get back rather than buying at peanuts and selling back more expensive
Your graphs show:-
Heating 24 hrs is cheapest not intermittent.
Fur 24 hour heating the difference in cost between 35 and 50 degrees is less than £100 per year cost for the typical house.
So the ROI in moving from 50 to 35 degrees is very long.
Best bang for your buck seems to just get a system cheap for 50 degrees that will cope?
Happy to be corrected...
PS.. This is the Octopus business model I believe
i think this is slightly misleading because we don't spec the radiator for constant use. the duty cycle for them even at the MCS outside temp is only meant to be about 50%?
you would never be able to heat the house if it was 100!
I’m on OctopusGo (cheap 0030 to 0430) with a solar & battery Heating is on set back from 10pm to 2am. Battery stops charging at 4.30am . On coldest of days we manage to get to 4pm before needing to draw from the grid. Our heating cost for January has gone from £235 on gas last year to £75 on electric with the ASHP
That's good to hear as I'm about to get a heat pump and run from batteries. I recently switched to Intelligent Octopus Go which gives 7.5p from 23:30 to 05:30 so would give you an extra 2 hrs.
I do have an electric car though
The panel/battery combination is a revelation. When I bought it originally I saw the battery as a means to store excess generation. However, since export rates have gone up and cheap overnight electricity we’ve made significant savings
Electric car is arriving soon (seems like I’ve been waiting for ages). As soon as it’s plugged in I’m switching to Intelligent. I’ll swap the timing for battery charge to end at 0530, that way the car won’t charge from the house battery
@gruff2001 yes, the off peak side of batteries is a real winner. As a point, you can set the "when I need the car ready" time on Intelligent Octopus Go to 05:30 to make sure the car doesn't charge from the home battery as well
@@mikeroberts8412 thx for that. Just had the phone call from dealer - car is ready for collection next week. That’ll be good bye to all fossil fuels in our household
I work in green energy. I worry this video is music to the gas industry's ears. The idea of heat pumps running 4-7pm will fill the electricity networks with dread.
This video is quite simplistic. The fact is that all heat pumps and emitters are oversized once you're above - 2C. COP is also far more dependent on outdoor temperature than flow temperature. There's a real argument for dynamic flow temperature control, with higher flow temperatures mid-afternoon when the air is warmest and using excess heat to ride through the evening electricity peak.
The basic problem is that controls are still rubbish (I've got an Ecodan - so this is particularly true). All heat pumps should be predictive of weather conditions, be using the house's thermal mass as buffer and calculate the cheapest way of keeping your house within a defined temperature range with smart tarriffs. SCOPs might improve that way, but cost, not SCOP, should be the target.
Your advice is probably correct for houses today, but it's not sustainable for a cheap, decarbonised grid.
I plan on programming my way through this with Home Assistant, but I'm not the average consumer.
Lots still to do!
No the premise in this video is that the Supliers have to vary the pricing much more in order to making shifting useage more viable and worth while
With setback overnight, wouldn't that normally be the same thing as turning off the AHSP most of the night? Unless it is really cold outside or the house has unusually high heat loss, the temperature will only drop to the set back temperature at say 5am or 6am. So, the ASHP will be off overnight. So setback would mean not steady state for 24 hours except on the coldest days. Is that right, or am I overlooking something?
If your comfort temp is 21 and set back 19 that could be like 23 hours as it’s colder at night
@@HeatGeek Sorry, are you saying that with a 2 degree set back the ASHP would only be off for an hour? That is, it would take an hour for the house to lose 2C on a cold night? So the ASHP would be operating 23 hours steady state?
If that's what you meant, I'm sceptical. I did some monitoring overnight on 27 Jan. It was 2C outside at midnight and it fell to 1C by 6am. Over those 6 hours my rooms fell by between 1C and 2.6C. On average, less than 2C. I think for my house a 2 degree setback would mean the ASHP would be off the whole night except on the handful of nights when the outside temperature is well below zero.
This is where thermal stores solves most of these problems and a 500l can store 25kwh and you could double this.
Heat pump using electricity for 6 hours that is 4 times cheaper at may be half the COP when it would not be used due to setback at night
Other benefits are longer heat pump run times and quicker response plus stops overheating due to solar gain
Please do a show on this!
But the efficiency drops off with higher temp so doesn’t work out
Aero therm 7kw. SCOP at 60C is 3. Effective SCOP*cost is 12 for a delta of 40C.
So even accounting for lower efficiency at night it is still far cheaper
@@HeatGeek agree. I have a biomass (Pellet) boiler which is quite cheap in use, heats up our 250 litre thermal store for heating and hot water, I believe these need to be separate. The system is oversized 13kWh heating/water 3kWh room heating and not very controllable which makes the house too dry and gives me dry/sore throat. The house is 144 sq meter, underfloor heating, radiators not used upstairs and an EPC of 100. I would love to have a heat pump installed but apparently we can’t get the BUS grant to help.
@HeatGeek According to your upgrade calculator I can receive the BUS grant, is this true?
Why could you not use the agile tariff but reduce the flow temp for the peak hours? Agile is the cheapest per unit cost of electricity
You can. This is a simplified illustration
The information about the heating requirements for underfloor heating is incorrect. I heat my home in Denmark at 35-40 degrees for 3-5 hours and the thermal mass of the building keeps us warm 21C until next day… our floors are very well insulated here 3/400mm of insulation under a 10cm concrete floor. So warming a floor to 120 degrees is way out!!!
See i cant work out if its worth it for my mum who has a heat pump, her controls are pretty dumb (council install) and she likes the heating on all the time but a lower temperature at night. It has no heat compensation and by looking at the graph nit a very efficient hot water tank as it tops up the temperature quite regularly. She has a cop in the 3s so not too bad but i just dont really kniw where to start to improve its efficiency and cost to run.
The system is possibly set for "Reheat" on the hot water. That could be changed.
Reprogramming the controller could work wonders. Our installer normally configures for set flow temperature (55') like that. I reprogrammed the system for weather compensation and operation that sounds similar to what your mum likes. We see flow temperatures below 45' and much better efficiency.
@@garrywhiting8398 thanks for the reply. I can't see any form of weather compensation be it on the terrible controller or the clunky app it's really annoying. Also no option to have seperate temperature for flow and water it just does both at the same temperature so I'm a little bit wary to bring it down because of legonella. My mum doesn't want the rads cooler but if I can work out a way to do it separately I will do it and not say just fora few days and see how it affects the cop. She has the water on constantly as she has a pain condition she likes to have regular baths as and when. It seems like the tank drops temperature soo quickly.wh en compared to my setup the water gets to temp and is still holding near enough the same temperature by the evening and I heat first thing in morning. It just seems really bad for a tank that's a couple years old. I also find it quite hard to find much info on the mitsubishi system. I also believe the system. Is well oversized for one bed bungalow aswell so not sure how that affects efficiency. My mind would suggest it would be better as the system wouldnt have to work so hard to get the job done. At the moment her bills aren't far behind mine and I heat my house 24/7 3 bed with 6 of us so something isn't adding up.
Disappointed that there wasn't more mention of Agile and avoiding 4-7pm. Prices outside this slot average 10-15p/kWh
Yes out spreadsheet wasn’t built for that. But we’re building a full on calculator for it instead. I think it will be pretty significant!
Nuclear + heat pump = ❤🌱
As Octopus Agile tariff is very cheap 4 hours in a day, how any hours in a day is it cheaper powering a HP with a sensible average COP of 3.5, what is the amount of storage and excess power would you need to use?
I can't afford to put the heating on anyway! Nonetheless, interesting video 😀
The two cheap rate periods help people with batteries. We'd need an enormous system to run our household and switch to a heat pump for heating.
Ovo have heat pump tariff for 15p per kwh
A premiere eh? Will Adam arrive via a red carpet?
Turn you house into a storage heater basically.
I have been keen on a heat pump. However, this video has really put me off. At present, I think the infrared panels will be better as they heat the room and its mass rather than the air.
Don't let it put you off. We went from storage heaters to heat pump. We are steady state but we have a daytime temp of 18 and night of 16. At the moment we're about £4 per day we're on eco 7 so hot water done during night and has a setback level of 40degrees during the day which we've never actually got down to.
@@AbbyB650 thanks. I'm really waiting for the Octopus Cosy Heat pumps as these look to give a better bang for buck over the current range of heat pumps. Considering we are likely to need colling, I am also looking at air to air as this may be a better solution, year around when paired with infrared in bathrooms etc...
@@davidgates3498 the Octopus unit is unlikely to run at high efficiencies from what we have seen of it. The company are likely to cover this by offering specific tariffs to adjust the costs. Daikin produce reversible versions of the Altherma to provide cooling. Personal comfort and efficiency is different between A2A and A2W. Many A2W users compare their comfort as being similar to (average) summer time ie "it's just comfortable. You don't really notice it cold or hot." Get onto the HG map and talk to one (or more) of your local Geeks, and possibly see an existing installation.
@@garrywhiting8398 thanks, time will tell about the Cosy. They are very slow at releasing any info on the product, especially as it was launched with such fanfare. Re the Heatgeek video, I love these videos, great info. This one really made me think about the instal. I really, really don't want any more or bigger radiators. Seeing as having these is quoted as being key to a necessity the. I think I'm really going to consider and extra powerwall and something else for heating like Infrared.
Yeah the Octopus Cosy is pants. What were they thinking?
Yeah Cosy was lose:lose in my opinion, we switched to Tracker and never looked back
I get the feeling it only has any relevance if you have a house battery to soak up the cheap periods.
Cosy only really makes sense when you setback during peak and shift hot water to the cheap periods. Whether you can save extra money via slightly boosting heating during cheap periods depends on your home insulation, lifestyle and installation.
Why do my figures come out so differently?
ruclips.net/video/6gtg6AZts1E/видео.html
Octopus tracker/Agile FTW for the typical heat pump home witbout battery storage.
I think the assumptions were the efficiency losses were based on outdoor design temp (e.g. -2C), whereas most of the year you don't need a larger unit or larger emitters and wouldn't drop down to .6 COP 😅
Averaged 12p/kWh for February on Agile so already beating OVO pricing and I don't have a battery to carry me through peaks.
Octopus tracker makes all of these seem expensive and pointless.
Is this video slightly disingenuous? At the time of writing this comment 17/3/24, Ovo Heat Pump tariff is only available to Vaillant HPs or supplied or installed HPs. This is not clear in the video, unless I missed it. I did wonder why the first 6 minutes was spent exploring a pretty ludicrous usage scenario with Octopus Cosy. This kind of content that appears to be customer centric, but is really a thinly veiled advert, leaves a bit of a bad taste. How can I trust the things you say in other videos?
There’s a few using cosy in the 6 hours and if you have a low temperature system it’s totally acceptable and incredibly cheap!
Ovo won’t only be offering this with vailant for long I would t think.. they want more customers
pls turn off the music.
disagree
Any part specifically?
@@HeatGeek I don’t think enough credit is given to the potential benefit of flexi pricing options. Yes at near freezing (-2oC) you aren’t going to have room to play tunes with prices (and zoning for that matter), but on warmer days or times when the price is even cheaper on flexi tarrif there is more room to do this.
@@fiable262626 so you don’t disagree, you think enough emphasis is put on part load shifting. There’s less energy and money to be saved there so could come out in the wash. Regardless we’re talking about small somes money. The money doesn’t reflect how important it may be to do though
@@HeatGeek Its a shame price flexing could cause your SCOP to go down, even if you save money. Needs to be a SCOC - seasonal coefficient of cost 😂.
Savings £30 or even up to £300 a year is not worth the hassle of switching to an Air Source Heat Pump, end of story.
Reached many of the same conclusions since looking at these tariffs. So good to have my research and worrying on this validated.