The way the octopus rep explained it to me is that with a SCOP of above 3, it makes the running costs better or equal to a boiler whilst keeping installation costs competitive to a regular boiler. They believe, that will entice more people to switch when they need their boiler replacing.
@@marcussmith6523 Most modern gas boilers run at an efficiency of 85% so once you factor that in, you don't need a COP of 4 to win. Depending where you are in the country, your rate may be 3.3-3.6 to break even. That's before you consider smart tariffs and other strategies that are opened up with heat pumps.
Thanks, great little video. I've had a few quotes recently from Aira, Octopus, and Heet Geek. My impression is that Aira and Octopus have the business strategy of not upgrading existing radiators (unless absolutely necessary), while, for example, Heat Geek push for massive radiator upgrades (even if not really needed) to chase high SCOPs. None of them are sufficiently transparent about it, though. They just give one design and most customers will have no idea that there are sensible alternatives. I'd prefer to get two proposed designs to choose from and some rough quantification of the trade-offs between them. For the urgently needed fast mass adoption of heat pumps, the Aira and Octopus strategy seems much more likely to succeed. Otherwise, the one-off expense of a gas-boiler to heat-pump retrofit will put off most households, and we end up burning more gas. Perhaps Heat Geek's strategy could be better targeted to new builds, where the cost of installing a properly designed low-temp heating system is lower than retrofitting an existing high-temp one?
To be fair, you only need to upgrade your system to low temperature once. A like for like HP change isn't dramatically different to a boiler swap. Get a quote for a new central heating system+ combi vs upgrade to low temperature system plus ASHP and cylinder and it wouldn't be that different. Everyone keeps telling me A2A is cheaper but I had a company quote me a £17 system for that, where as my ASHP quote through octopus is £7500 , heat geek £10,000. A new boiler on the existing system might be £3000 but with a cylinder we might be talking £5000 and if I needed or wanted it to actually condense the same radiator changes would mean it's suddenly near exactly the same as the post grant prices.
@@Lewis_Standing I've been quoted over £17,000 for just a heat pump (5kW) + a hot water cylinder (no new radiators) upgrade. And the cylinder upgrade was non-negotiable because my existing (nearly new) cylinder has only 1m2 heat exchanger surface, which is too small for a heat pump hot water heating. Even after the BUS grant, it's still 10 grand. This is just for the rich and geeky. No-nonsense no-SCOP-chasing affordable upgrades (like what Octopus offers?) are the way to go, as long as they're done sensibly (without killing performance by poor installation/controls).
Be wary of Aira, one of the guys on a forum I'm on has had no end of problems, very poor at answering the phone and sorting issues by all accounts, left the house in a right state as well.
"efficiency" can also be ROI (return on investment) thing, so avoiding the retrofit cost you mentioned is an important part of the marketing push to heat pumps. We can be our own worst enemy with some of the nitpicking, as most folks in the mainstream media are regurgitating really old info such as need for all radiators needing replaced and all piping. Stories from 15 years ago are still going around as 'current' problems. Being _able_ to operate at a higher flow temp can be a big win for those with smaller radiators and microbore, once they've got a few simple low cost insulation feature installed, so lets be more pragmatic and understanding about who this is aimed at.
I had not seen the original video you're reacting to but you've covered my thoughts exactly. I'm not expecting as much efficiency as an amazing Heat Geek Ultra installation would provide me with, but at the same time, my system pipework isn't going to be replaced and the new radiators that are planned to be installed will not be much larger than before, save for the bathroom one which really needs to be bigger anyway. When I'm paying £540 per annum for gas at current prices including the standing charge, there really isn't much scope for saving a lot of money on that, and I think the right balance for me is struck by Octopus's offering.
Interesting! The proposal for mine is mostly similar sizes also but replacing with doubles with either single-sided or double-sided convectors. Perhaps it's similar. None of them are triples. There's plenty of space for the one in the bathroom to grow which is the only one that's going to be significantly larger.
I like what octopus is offering as a product. I don't think much of some of their marketing. Either way, we need them to succeed otherwise heat pumps are doomed.
I think the octopus strategy os that its better to try roll out 270,000 high temp lower performance ASHP successfully, than engage on a bespoke slow and painstaking low temp revolution and deliver a lot less due to the design choices and retrofit requirements. Personally I'm getting a low temp system installed by a heat geek but I'm not the avg person with a strong environmental desire and funds. Avg Joe may be happy with high temp, no new rads and a tarrif that just about makes it cost competitive vs gas.
Then why not just use A2AHP that don't care about flow temperature or weather compensation then. A SCOP of 3 is meh compared to 6 that can be achieved with good japanese AC units.
@@johnzach2057 A2A won't achieve 6 in the real world. Proper measuring equipment is eye wateringly expensive and lab testing procedures don't represent real world at all. People who have attempted to perform real world in home measurements are coming back with a COP of 3-4. This is of course irrelevant, as the ability to zone and not have to run 24/7 like A2W does, can save big time on the overall consumption cost. So I do believe that for some people, A2A will still have much lower running costs and of course lower installation costs for many too if you discount the grant.
@@UpsideDownFork Actually it does. People here have measured COPs up to 10 when temperatures are 14C. And SCOP in Athens was a little bit better than the sticker. But this only applies to the really good Fujutsu and Toshiba models priced at around 1000-1500 euros for the 8kw systems and contrary to current A2WHP that turn off at 30% load, Fujitsu and Toshiba units keep running at 10% load with extremely high COPs. 8kw units have been seen running @ 100-150W which you will never see in 8KW A2WHP. So actually, in contrast to A2WHP it's better to oversize them. The bigger unit the better COP you'll get. Another huge huge plus is the availability of A2A units that can directly connect to solar panels since they have their own MPPTs and they don't need inverters. They are excellent for warmer climates where cooling is a must and almost totally reduce electricity consumption during summertime. They also help in the winter but I guess for the UK the benefit will be small since solar energy production collapses from December to February.
@johnzach2057 which method of testing have they used? Do they have vested interests to come to those incredibly high figures? Can you point me to this data please?
Sinplely from a thermodynamics perspective, the smaller the temperature difference between evaporator and condenser the more efficient it will be. As the pressure differential will not need to be as high and thus the compressor does less work compressing the refrigerant using less power pumping and higher mass flow of refrigerant moving more heat.
Octo knows that most people aren't very bright, and fear change, so they want to keep the user experience with a HP as close as possible to their existing gas boiler. So; keep the rads nice and hot and don't charge very much for the installation. It's a good strategy, as others have said, and there is the opportunity to make further savings using tariffs.
2:32 i didn't knew that large heatpumps are this efficient at high flow temperature, 3.6 is not that bad. Maybe that's why some installers are over sizing it to 12KW when they do retrofit with older radiators (i'm not claiming that it is good or bad idea).
Larger heat pumps will have a larger evaporator, so have more surface area to collect heat from. Basically, a bigger heat pump doesn't mean less efficiency, if it's installed in a property for the correct heat loss.
Large heat pumps don't necessarily equal oversized. If a 14kW heat pump is the correct size for a property then you can achieve a SCOP over 4, no issues. But if a 14kW is bolted onto a house with a heat loss of 7kW, that pump will not be able to shed sufficient heat into the property and will short cycle. The inefficient stage of a heat pump is when it starts a cycle. This is why the whole system needs to be correctly sized. Also, last point, higher or lower flow temps aren't really anything at all to do with heat pump sizing (albeit inter-related). Flow temps are dictated by radiator size. If you have a heat loss of 7kW and you don't want to change rads, you can use the same heat pump at a 55 degree flow temp as if you changed your rads and lowered the flow temp to 45 degrees. Hope that all makes sense.
They need to re-do the video. they are using one of the new refrigerant gases so they can run the whole system much warmer so that houses with microbore systems can have a heat pump fitted without ripping the whole system out, yes it may be a bit more expensive to run but much cheaper to install. EVNick is doing an interesting series on his octopus install.
Indeed he is. That's also sort of undermining the claims made by Octopus energy that it's a fit & go solution. Needing a buffer tank and secondary circulation pump for the heating circuit makes the Cosy 6 no different to the Daikin's they were previously installing. They're still designing the system temp to 50 degree flow, so the same number of rads will be changed.
@@edc1569he's most certainly bias. When you read his comments on Twitter there is lots of 'fingers in the ears' not accepting what people are criticising about his install. He basically loves Octopus and wont hear a word against them. I can fully appreciate their strategy of 50C flow rates myself, it means they can knock the systems out quick and cheap. On a path towards net zero, it makes the biggest inroads. BUT I do think they should make customers aware that they could spend more, change rads/pipes/etc, maybe not need to run with a buffer and extra pump(s) and overall get better efficiency. Really it should be like the fact sheets you get with banks, they should have pre-canned options which give pro's and con's to customers and let the customer decide if they want to spend more for more efficiency. This is especially true if a customer could easily/cheaply do some minor upgrades to allow for a lower flow temp. Why fix it at 50C? That's only really a line in the sand to allow for quicker and easier designs on their side, not benefiting the customer when a small amount of work could lead to a much better install.
@@cingramuk I gather that you _can't_ change the flow temp on an Octopus install. They don't let you. I'm glad I didn't go that route. Not getting all the knobs myself on my own heating kit is a deal-breaker.
Given that most heat loss estimates are erring on the side of extreme caution, I suspect that most installations will actually need only max flow temp of 45. They are not shy about chaning rads. In my quote they didn’t originally plan to change the main bedroom rad as is was at 98.5% of the heat losss calc (within tolerance). All,other bedrooms were at around 105-110% of heat loss, so I asked to change that rad to match the other bedrooms and not createminbalance. Cost was about £100 for the rad and the fitting.
@@AdrianColes Yes, I've seen that most installations do run below design temp which is good for flow temp and rad sizing but not good for modulation. 👍
So I assume the compressor is what is modulated to adjust the rate of heat exchanged with the water? I'm only starting to think about this, to be honest I am settling on a new oil boiler and solar panels at the moment. These heat pumps just don't seem to cost right and I am banking on next gen oil alternatives.
@@3d1e00 I looked into these for a family member. Only modulate down to 6kW, so equivalent to a massive 18kW heat pump. Still need the mess and expense of a tank. Boiler itself is not cheap as i'm sure you're aware. No grants or VAT relief. Likely less comfortable heat depending on your specific heat loss and system design. And then there's the associated emissions for both local air quality and wider climate change. Even using HVO does not equal zero emissions and particulate matter.
@UpsideDownFork yeah but zero emissions is a little bit of a stretch but I got what you mean. Shame if it's only 6kw I will give them a shout. May just use a Tado on my old oil boiler for a bit if crap. Thank you for information mate.
@@3d1e00 Tado is a good stop gap for most boilers because even if you can't use BUS controls through a protocol like Opentherm, every boiler can be quasi modulated through Tado's smart PWM approach.
Can somebody explain why on the Octopus WC graph the flow temp is above 25° when it's 20° outside? Surely you don't need heating when it's 20° outside. TBH we don't need heating when the outside temp is above about 12° or less if the sun is shining. You'll already have people and appliances generating more than enough heat.
@@johnhunter4181 correct. An adult at rest will emit ~100W, not to mention all the other thermal gains. We have our heat pump set to off once the OT reaches 17 degrees for this reason. 👍
Lower flow temperatures require higher flow rate for the same power output. Higher flow rates require larger pipes = higher retrofit installation cost. Designing for lower temperature flow requires calculating the system pressure loss to size the pipes correctly. It is simpler for them just to say "Sometimes lower temperatures are less efficient." Because it is true for a system installed with pipe work too small for a lower temperature. But it is not true in general. Is this what's going on here?
Great video. We got a quote from Octopus and I think the Cosy 6 is a really interesting heat pump and perhaps my preferred choice if we were to go for a 50deg design flow temp. Instead we've gone for a 45deg install with a Vaillant as that's better and our existing pipework is sufficient. I told the Octopus rep we wanted a 45deg install. It's most likely that Octopus are getting a lot of similar feedback which may have prompted TJ to respond with a video pointing out the weather compensation curve. P.S. do you have a link to that Vaillant datasheet?
Vaillant have put much of their literature behind a technician login now. I've scraped as many of these documents as I could get my hands on and have uploaded them to the files section of the Vaillant Arotherm UK group.
I've just booked a heat loss survey and getting ready to go for a heat pump and havinv my gas boiler removed. I generally understand the concept of how HP's work, weather compensation too, but not yet understood how they communicate. Some can be remotely monitored and controlled with an app so need an Internet connection (not a problem). Is this Internet connection a cable to the heatpump outside or is it wireless, or does the heatpump send it to a controller inside the house that is then wirelessly connected?
It really doesn't matter. The vast majority of consumers will buy heat pumps once it's clear that a) it will cost much less to stay comfortable in their homes b) they can afford the cost of the change from gch to heat pump systems. Prosumers or professionals that can interrogate design parameters and optimise a system to achieve higher coefficients in the medium term - are a small but vocal minority. Fair enough. My recommendation is the hire an engineer to design your system based on a building inspection (thermals & drafts). The lowest cost highest impact interventions may be to replace windows or renew loft insulation. But that's not sexy I guess
It certainly isn't, my Daikin runs at a nominal 34C. In saying that, my very old gas heating system was totally replaced from ground up (cost me just under £4k after grant). I suspect what the suggestion was that it's more beneficial to get heat pumps installed than worrying too much about all systems being as efficient as possible (but I could be wrong 😉😉).
35 degree DESIGN temperature is difficult in many properties as the radiators would just need to be too large to be practical. But properties designed for 45/50 temp will usually have a working flow temp of 25-35 degrees for most of the heating season.
@trailblazer7108 that's such a broad question. COP? Yes. SCOP? No. Properties reaching SCOPs of 5 are properly optimised. This may mean insulation, underfloor heating or correctly sized radiators, totally dependent on the property.
TJ is the "Heat Flexibility Director" - what on earth is that job role and what does it entail? Does appear as you say he doesn't appear to have a scooby what he is talking about...................... Maybe he should go on the Heat Geek Training before doing another video?? Also as you and several others have commented - they designed a Hight Temperature Heat Pump that is less efficient than most Low Temperature Heat Pumps @ 50'C. What is the point of bringing out a HT Heat Pump that are the same or less efficient than LT Heat Pumps at higher temperatures???? The point where you discuss Octopus talking about higher flow temps/bigger radiators is moot as they would still need increased size radiators due to the simple fact that Gas Boilers operate on a Delta T of 20'C and ASHP will use 5-7'C Plus I thought the accepted rule of thumb was 3% efficiency gain for every 1'C reduction to 50-40'C would be a 30% performance increase. not 12%....
Integrating the controls of the heat pump with when it's cheapest for the grid and octopus to deliver the electricity for it, to offer you a better tariff price. So the efficiency might be lower with their high temperature system, but they might be able to do some tariff magic to make it a similar cost to run.
50% of the running cost savings is because bigger emitters easily run much lower temps. If people do not size up emitters, they will have to run higher flow temps, it's so obvious a child can understand it. Selling something that is linked to power tariffs sold by only one provider is surely misleading marketing? And suggesting that even some old gas emitter sizing will work with heat pumps is just silly, and wrong. I don't understand resistance to larger emitters, especially if better efficiency and therefore lower power bills are guaranteed. I have two huge emitters in my very modestly sized living room, one behind the sofa, one behind a large armchair, they do not distract the eye in any way. Final thought - not enough is being said about allowing the best airflow for emitters. Emitters are not radiators because they only radiate about 10% of their heat, the other 90% is convected, so anything preventing free flow to the bottom and from the top of an emitter will damage efficiency.
Great comment! I agree! There is an argument that radiators do actually radiate a larger proportion of their energy at lower flow temps and as the thermal mass is built up in a room there are less convection currents to transfer the energy from the emitter. But yeah, allowing airflow is just so self explanatory my kids do understand all this!
Sounds like he shot himself in foot, the lower the flow temperature the better the performance. My Daikin system runs well @ 34C flow. Edit:- was designed for 45C @ -3.5C external. I currently run it on flow control set between 34-36C, energy consumption is 400- 650W, with zero cycling other than switching to HWC.
@@UpsideDownFork There's a whole story behind this 🙂 Are we all sitting comfortably....... Back in February, my HP was installed, like many here I had read as much as I could the previous year into this 'new' technology called heat pumps. There were a few triggers for me that made me finally decide to jump, one of which was your British Gas install. Another, perhaps most influential, being the Glyn Hudson self install in his Welsh stone cottage, I thought if it works there it can work anywhere, thus dispelling the myths of the naysayers. ruclips.net/video/Hyv_vQEvHgo/видео.html My Daiken 6kW HP sits in a sun trap of a corner; 'all good and well' I thought, additional direct Solar boost. In practice however the external thermostat resides in the Monoblock unit, Daikin themselves via installation instructions manual ask for an additional thermostat on North facing wall to be fitted (not on my unit), to alleviate the affects of solar gain whereby my unit thinks its 25C, whereas its actually 15C air temperature ( 🥶) when Sun's out. In practice I tried weather compensation, but cycled too often for my likening, so I thought I would experiment with fixed flow temperature....... For the bulk of the year (above 3C) the 34C flow seems to give good result, with the input power rising to 518W as I type (3.5C external). I will see how this fares over winter, and probably poke a stick at weather compensation, for a week or two and see if it fares any better in colder month/weeks. You can see my data on heatpumpmonitor (Aberdeenshire, other metering, British Gas). The COP is based on the post process 'Carnot COP' simulator, as I do not have an independent flow meter fitted. However the Daikin control unit reports higher COP value than heatpumpmonitor (I was conservative in choosing a 'practical_efficiency_factor' of 0.45 in 'Carnot COP simulator' (an algorithm that gives a good 'ball park' figure for COP without flow rate (litres/minute). For avoidance of doubt the Daikin HP has a flow meter, supports full weather compensation, shows flow reading, but data not easily transferrable to Emoncms App', and being own manufacturer the COP value shown on Daikin display may suffer from the 'Diesel gate' syndrome.
@@UpsideDownFork I don't know, but a box, digital thermometer, bit of cable, I don't suppose it would be a dear item. I should really badger BG to fit one, I quite like the results using flow control, outside temperature has just risen above 10C (11.2C) and it's consuming 377 Watts which is the lowest I can get it to run stable at.
I don't think his video is that confused, though perhaps the info about weather comp is a bit misleading. I've always understood the design temperature to be the outdoor temperature at which the heat loss for the property has been calculated, nothing to do with the flow temperature, but maybe my understanding is wrong. He's talking about people complaining about the flow temperature they are specifying at that design temperature, and then explaining that this flow temperature is only used at the design temperature. Yes, they could be designing to lower flow temp to achieve the desired room temperatures at the design temp, but as pointed out it seems that may never pay for itself, and would give them many more problem installs (everything they upgrade is another possible point of failure).
It's worrying that the professional business has worse communication on this topic than (presuming you aren't doing this full time) an amateur that isn't even in the heat pump trade... To be honest, in my experience so far, amateurs are often more knowledgeable than heat pump professionals. Mainly because the "pros" have been doing it decades and stuck in their ways. Or are trying to pedal a system which is optimised for the fitter rather than the user. Example being this Octopus misinformation effectively distracting from the truth that they've minimised installation costs at the cost of efficiency, which they think is worth it.
Seconded. I saw an Artisan electrics video about 'best home batteries', which turned out to be best batteries from the installers' POV, not the customers. And it entirely failed to mention most of the better value options. OK, that's PV/ESS not heat pumps, but same principle. I'm also permanently annoyed that DIYers are excluded from all grants for this stuff. They don't just provide good advice - they often do very good work too. Grants should be based on outcomes/standards, not club memberships.
ruclips.net/video/BP_pqSlh7es/видео.htmlsi=2nfVvNaPYCOWmQ6v same thing here, does not make sense to me. but they suggest the higher flow temp allows it to run for a shorter time with longer off times that compensates for the lower COP of a higher flow. the opposite of what i understand, that low temp over long wins the efficiency game.
I've got some thoughts on that but probably for a separate video. Compressor can't modulate low enough, circulation pump can't flow enough, perhaps emitters can't shed anymore energy into a modern, well insulated property... it's a recipe for failure.
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The way the octopus rep explained it to me is that with a SCOP of above 3, it makes the running costs better or equal to a boiler whilst keeping installation costs competitive to a regular boiler. They believe, that will entice more people to switch when they need their boiler replacing.
It's a good business model, it just needs some clearer messaging.
@UpsideDownFork yer, they only explained this to me after I asked why their cost was so low compared to other companies.
Electric costs 4 times the price of gas per kwh so ideally a cop of 4 needed.
@@marcussmith6523 Most modern gas boilers run at an efficiency of 85% so once you factor that in, you don't need a COP of 4 to win.
Depending where you are in the country, your rate may be 3.3-3.6 to break even. That's before you consider smart tariffs and other strategies that are opened up with heat pumps.
Thanks, great little video. I've had a few quotes recently from Aira, Octopus, and Heet Geek. My impression is that Aira and Octopus have the business strategy of not upgrading existing radiators (unless absolutely necessary), while, for example, Heat Geek push for massive radiator upgrades (even if not really needed) to chase high SCOPs. None of them are sufficiently transparent about it, though. They just give one design and most customers will have no idea that there are sensible alternatives. I'd prefer to get two proposed designs to choose from and some rough quantification of the trade-offs between them. For the urgently needed fast mass adoption of heat pumps, the Aira and Octopus strategy seems much more likely to succeed. Otherwise, the one-off expense of a gas-boiler to heat-pump retrofit will put off most households, and we end up burning more gas. Perhaps Heat Geek's strategy could be better targeted to new builds, where the cost of installing a properly designed low-temp heating system is lower than retrofitting an existing high-temp one?
To be fair, you only need to upgrade your system to low temperature once.
A like for like HP change isn't dramatically different to a boiler swap.
Get a quote for a new central heating system+ combi vs upgrade to low temperature system plus ASHP and cylinder and it wouldn't be that different.
Everyone keeps telling me A2A is cheaper but I had a company quote me a £17 system for that, where as my ASHP quote through octopus is £7500 , heat geek £10,000.
A new boiler on the existing system might be £3000 but with a cylinder we might be talking £5000 and if I needed or wanted it to actually condense the same radiator changes would mean it's suddenly near exactly the same as the post grant prices.
@@Lewis_Standing I've been quoted over £17,000 for just a heat pump (5kW) + a hot water cylinder (no new radiators) upgrade. And the cylinder upgrade was non-negotiable because my existing (nearly new) cylinder has only 1m2 heat exchanger surface, which is too small for a heat pump hot water heating. Even after the BUS grant, it's still 10 grand. This is just for the rich and geeky. No-nonsense no-SCOP-chasing affordable upgrades (like what Octopus offers?) are the way to go, as long as they're done sensibly (without killing performance by poor installation/controls).
Thanks for commenting. I'm glad we have a few choices in the market and we're seeing some healthy competition too.
We're having our Cozy 6 installed this week, £500 all in and Octopus are replacing 6 of our 8 main radiators.
Be wary of Aira, one of the guys on a forum I'm on has had no end of problems, very poor at answering the phone and sorting issues by all accounts, left the house in a right state as well.
"efficiency" can also be ROI (return on investment) thing, so avoiding the retrofit cost you mentioned is an important part of the marketing push to heat pumps.
We can be our own worst enemy with some of the nitpicking, as most folks in the mainstream media are regurgitating really old info such as need for all radiators needing replaced and all piping. Stories from 15 years ago are still going around as 'current' problems.
Being _able_ to operate at a higher flow temp can be a big win for those with smaller radiators and microbore, once they've got a few simple low cost insulation feature installed, so lets be more pragmatic and understanding about who this is aimed at.
Good point ☝️
I had not seen the original video you're reacting to but you've covered my thoughts exactly. I'm not expecting as much efficiency as an amazing Heat Geek Ultra installation would provide me with, but at the same time, my system pipework isn't going to be replaced and the new radiators that are planned to be installed will not be much larger than before, save for the bathroom one which really needs to be bigger anyway. When I'm paying £540 per annum for gas at current prices including the standing charge, there really isn't much scope for saving a lot of money on that, and I think the right balance for me is struck by Octopus's offering.
My heat geek proposed installation involves turning the rads to doubles or triples but not really any size increases.
Interesting! The proposal for mine is mostly similar sizes also but replacing with doubles with either single-sided or double-sided convectors. Perhaps it's similar. None of them are triples. There's plenty of space for the one in the bathroom to grow which is the only one that's going to be significantly larger.
I like what octopus is offering as a product.
I don't think much of some of their marketing.
Either way, we need them to succeed otherwise heat pumps are doomed.
@@UpsideDownForkmaybe you could link the original video?
I think I agree with the Octopus approach, the system only operates at Design Temp very rarely.
Fair enough.
I think the octopus strategy os that its better to try roll out 270,000 high temp lower performance ASHP successfully, than engage on a bespoke slow and painstaking low temp revolution and deliver a lot less due to the design choices and retrofit requirements.
Personally I'm getting a low temp system installed by a heat geek but I'm not the avg person with a strong environmental desire and funds.
Avg Joe may be happy with high temp, no new rads and a tarrif that just about makes it cost competitive vs gas.
Yep, agreed!
Then why not just use A2AHP that don't care about flow temperature or weather compensation then. A SCOP of 3 is meh compared to 6 that can be achieved with good japanese AC units.
@@johnzach2057 A2A won't achieve 6 in the real world. Proper measuring equipment is eye wateringly expensive and lab testing procedures don't represent real world at all.
People who have attempted to perform real world in home measurements are coming back with a COP of 3-4.
This is of course irrelevant, as the ability to zone and not have to run 24/7 like A2W does, can save big time on the overall consumption cost.
So I do believe that for some people, A2A will still have much lower running costs and of course lower installation costs for many too if you discount the grant.
@@UpsideDownFork Actually it does. People here have measured COPs up to 10 when temperatures are 14C. And SCOP in Athens was a little bit better than the sticker. But this only applies to the really good Fujutsu and Toshiba models priced at around 1000-1500 euros for the 8kw systems and contrary to current A2WHP that turn off at 30% load, Fujitsu and Toshiba units keep running at 10% load with extremely high COPs. 8kw units have been seen running @ 100-150W which you will never see in 8KW A2WHP. So actually, in contrast to A2WHP it's better to oversize them. The bigger unit the better COP you'll get.
Another huge huge plus is the availability of A2A units that can directly connect to solar panels since they have their own MPPTs and they don't need inverters. They are excellent for warmer climates where cooling is a must and almost totally reduce electricity consumption during summertime. They also help in the winter but I guess for the UK the benefit will be small since solar energy production collapses from December to February.
@johnzach2057 which method of testing have they used?
Do they have vested interests to come to those incredibly high figures?
Can you point me to this data please?
Sinplely from a thermodynamics perspective, the smaller the temperature difference between evaporator and condenser the more efficient it will be. As the pressure differential will not need to be as high and thus the compressor does less work compressing the refrigerant using less power pumping and higher mass flow of refrigerant moving more heat.
👍🙂
Octo knows that most people aren't very bright, and fear change, so they want to keep the user experience with a HP as close as possible to their existing gas boiler. So; keep the rads nice and hot and don't charge very much for the installation. It's a good strategy, as others have said, and there is the opportunity to make further savings using tariffs.
That's a good concise summary.
2:32 i didn't knew that large heatpumps are this efficient at high flow temperature, 3.6 is not that bad. Maybe that's why some installers are over sizing it to 12KW when they do retrofit with older radiators (i'm not claiming that it is good or bad idea).
Larger heat pumps will have a larger evaporator, so have more surface area to collect heat from. Basically, a bigger heat pump doesn't mean less efficiency, if it's installed in a property for the correct heat loss.
3.6 is break even with gas.
If paying a lot of money for a heating system improvement, SCOPs over 4 at least save you a little on heating costs too
Large heat pumps don't necessarily equal oversized.
If a 14kW heat pump is the correct size for a property then you can achieve a SCOP over 4, no issues.
But if a 14kW is bolted onto a house with a heat loss of 7kW, that pump will not be able to shed sufficient heat into the property and will short cycle.
The inefficient stage of a heat pump is when it starts a cycle.
This is why the whole system needs to be correctly sized.
Also, last point, higher or lower flow temps aren't really anything at all to do with heat pump sizing (albeit inter-related). Flow temps are dictated by radiator size.
If you have a heat loss of 7kW and you don't want to change rads, you can use the same heat pump at a 55 degree flow temp as if you changed your rads and lowered the flow temp to 45 degrees.
Hope that all makes sense.
@@Lewis_StandingJan Rosenow has break even at 3.3 SCOP in the UK.
They need to re-do the video. they are using one of the new refrigerant gases so they can run the whole system much warmer so that houses with microbore systems can have a heat pump fitted without ripping the whole system out, yes it may be a bit more expensive to run but much cheaper to install. EVNick is doing an interesting series on his octopus install.
Indeed he is. That's also sort of undermining the claims made by Octopus energy that it's a fit & go solution.
Needing a buffer tank and secondary circulation pump for the heating circuit makes the Cosy 6 no different to the Daikin's they were previously installing. They're still designing the system temp to 50 degree flow, so the same number of rads will be changed.
I don't think he's a source of unbiased info, wasn't his install video all sponsored?
@@edc1569he's most certainly bias. When you read his comments on Twitter there is lots of 'fingers in the ears' not accepting what people are criticising about his install. He basically loves Octopus and wont hear a word against them.
I can fully appreciate their strategy of 50C flow rates myself, it means they can knock the systems out quick and cheap. On a path towards net zero, it makes the biggest inroads. BUT I do think they should make customers aware that they could spend more, change rads/pipes/etc, maybe not need to run with a buffer and extra pump(s) and overall get better efficiency. Really it should be like the fact sheets you get with banks, they should have pre-canned options which give pro's and con's to customers and let the customer decide if they want to spend more for more efficiency. This is especially true if a customer could easily/cheaply do some minor upgrades to allow for a lower flow temp. Why fix it at 50C? That's only really a line in the sand to allow for quicker and easier designs on their side, not benefiting the customer when a small amount of work could lead to a much better install.
@@edc1569yes, his is a sponsored installation and video series.
@@cingramuk I gather that you _can't_ change the flow temp on an Octopus install. They don't let you. I'm glad I didn't go that route. Not getting all the knobs myself on my own heating kit is a deal-breaker.
Given that most heat loss estimates are erring on the side of extreme caution, I suspect that most installations will actually need only max flow temp of 45. They are not shy about chaning rads. In my quote they didn’t originally plan to change the main bedroom rad as is was at 98.5% of the heat losss calc (within tolerance). All,other bedrooms were at around 105-110% of heat loss, so I asked to change that rad to match the other bedrooms and not createminbalance. Cost was about £100 for the rad and the fitting.
@@AdrianColes Yes, I've seen that most installations do run below design temp which is good for flow temp and rad sizing but not good for modulation. 👍
I would like to know how to increase the flow temperatye on a cosy 6
You and hundreds of other owners. Octopus has full control, not you.
@@UpsideDownFork When it was 1st installed I could alter it on the app but that facilaty has dissapeared
@@fester9090 Octopus have confirmed that they've taken it away but not confirmed whether it will come back. 🤔
So I assume the compressor is what is modulated to adjust the rate of heat exchanged with the water? I'm only starting to think about this, to be honest I am settling on a new oil boiler and solar panels at the moment. These heat pumps just don't seem to cost right and I am banking on next gen oil alternatives.
That's correct. Inverter driven compressors that can typically modulate down to ~30%.
An oil boiler would be a mistake for many reasons.
@UpsideDownFork there is a boiler called a sapphire something that is a oil modulator.
@@3d1e00 I looked into these for a family member.
Only modulate down to 6kW, so equivalent to a massive 18kW heat pump.
Still need the mess and expense of a tank.
Boiler itself is not cheap as i'm sure you're aware.
No grants or VAT relief.
Likely less comfortable heat depending on your specific heat loss and system design.
And then there's the associated emissions for both local air quality and wider climate change. Even using HVO does not equal zero emissions and particulate matter.
@UpsideDownFork yeah but zero emissions is a little bit of a stretch but I got what you mean. Shame if it's only 6kw I will give them a shout. May just use a Tado on my old oil boiler for a bit if crap. Thank you for information mate.
@@3d1e00 Tado is a good stop gap for most boilers because even if you can't use BUS controls through a protocol like Opentherm, every boiler can be quasi modulated through Tado's smart PWM approach.
Can somebody explain why on the Octopus WC graph the flow temp is above 25° when it's 20° outside? Surely you don't need heating when it's 20° outside. TBH we don't need heating when the outside temp is above about 12° or less if the sun is shining. You'll already have people and appliances generating more than enough heat.
@@johnhunter4181 correct. An adult at rest will emit ~100W, not to mention all the other thermal gains.
We have our heat pump set to off once the OT reaches 17 degrees for this reason. 👍
Lower flow temperatures require higher flow rate for the same power output. Higher flow rates require larger pipes = higher retrofit installation cost. Designing for lower temperature flow requires calculating the system pressure loss to size the pipes correctly. It is simpler for them just to say "Sometimes lower temperatures are less efficient." Because it is true for a system installed with pipe work too small for a lower temperature. But it is not true in general. Is this what's going on here?
That might be just about the gist of it.
Great video. We got a quote from Octopus and I think the Cosy 6 is a really interesting heat pump and perhaps my preferred choice if we were to go for a 50deg design flow temp. Instead we've gone for a 45deg install with a Vaillant as that's better and our existing pipework is sufficient. I told the Octopus rep we wanted a 45deg install. It's most likely that Octopus are getting a lot of similar feedback which may have prompted TJ to respond with a video pointing out the weather compensation curve.
P.S. do you have a link to that Vaillant datasheet?
Vaillant have put much of their literature behind a technician login now.
I've scraped as many of these documents as I could get my hands on and have uploaded them to the files section of the Vaillant Arotherm UK group.
I've just booked a heat loss survey and getting ready to go for a heat pump and havinv my gas boiler removed. I generally understand the concept of how HP's work, weather compensation too, but not yet understood how they communicate. Some can be remotely monitored and controlled with an app so need an Internet connection (not a problem). Is this Internet connection a cable to the heatpump outside or is it wireless, or does the heatpump send it to a controller inside the house that is then wirelessly connected?
Most of them have a communication cable between the external unit and the internal unit which then connects to your WiFi network.
When is the A2AHP video coming!!!!
I have just finished putting it together and it is now in the queue, scheduled for publishing on 30th November.
It really doesn't matter. The vast majority of consumers will buy heat pumps once it's clear that a) it will cost much less to stay comfortable in their homes b) they can afford the cost of the change from gch to heat pump systems.
Prosumers or professionals that can interrogate design parameters and optimise a system to achieve higher coefficients in the medium term - are a small but vocal minority. Fair enough.
My recommendation is the hire an engineer to design your system based on a building inspection (thermals & drafts). The lowest cost highest impact interventions may be to replace windows or renew loft insulation. But that's not sexy I guess
Thanks for commenting.
When you paused it ,it looks like hes about to say f**k ive messed that up.
Oops! 😬
As in 'folk I've messed that up' 😉
I didn’t fully understand - are you suggesting that a 35 degrees flow temperature is practically unachievable?
It certainly isn't, my Daikin runs at a nominal 34C. In saying that, my very old gas heating system was totally replaced from ground up (cost me just under £4k after grant).
I suspect what the suggestion was that it's more beneficial to get heat pumps installed than worrying too much about all systems being as efficient as possible (but I could be wrong 😉😉).
35 degree DESIGN temperature is difficult in many properties as the radiators would just need to be too large to be practical.
But properties designed for 45/50 temp will usually have a working flow temp of 25-35 degrees for most of the heating season.
@@UpsideDownFork is it reasonably possible to get a COP / SCOP of 5 without absolutely enormous radiators?
@trailblazer7108 that's such a broad question. COP? Yes. SCOP? No.
Properties reaching SCOPs of 5 are properly optimised. This may mean insulation, underfloor heating or correctly sized radiators, totally dependent on the property.
@ thank you!
TJ is the "Heat Flexibility Director" - what on earth is that job role and what does it entail?
Does appear as you say he doesn't appear to have a scooby what he is talking about...................... Maybe he should go on the Heat Geek Training before doing another video??
Also as you and several others have commented - they designed a Hight Temperature Heat Pump that is less efficient than most Low Temperature Heat Pumps @ 50'C.
What is the point of bringing out a HT Heat Pump that are the same or less efficient than LT Heat Pumps at higher temperatures????
The point where you discuss Octopus talking about higher flow temps/bigger radiators is moot as they would still need increased size radiators due to the simple fact that Gas Boilers operate on a Delta T of 20'C and ASHP will use 5-7'C
Plus I thought the accepted rule of thumb was 3% efficiency gain for every 1'C reduction to 50-40'C would be a 30% performance increase. not 12%....
Integrating the controls of the heat pump with when it's cheapest for the grid and octopus to deliver the electricity for it, to offer you a better tariff price.
So the efficiency might be lower with their high temperature system, but they might be able to do some tariff magic to make it a similar cost to run.
He must know what he's doing. Octopus have installed thousands of heat pumps successfully. I just think this is one bad example of PR.
The whole point of the push for heat pumps is to come off fossil fuels. The price of your electricity is the key in the UK.
Yep, the merit order has a lot to answer for!
50% of the running cost savings is because bigger emitters easily run much lower temps. If people do not size up emitters, they will have to run higher flow temps, it's so obvious a child can understand it. Selling something that is linked to power tariffs sold by only one provider is surely misleading marketing? And suggesting that even some old gas emitter sizing will work with heat pumps is just silly, and wrong. I don't understand resistance to larger emitters, especially if better efficiency and therefore lower power bills are guaranteed. I have two huge emitters in my very modestly sized living room, one behind the sofa, one behind a large armchair, they do not distract the eye in any way. Final thought - not enough is being said about allowing the best airflow for emitters. Emitters are not radiators because they only radiate about 10% of their heat, the other 90% is convected, so anything preventing free flow to the bottom and from the top of an emitter will damage efficiency.
Great comment! I agree!
There is an argument that radiators do actually radiate a larger proportion of their energy at lower flow temps and as the thermal mass is built up in a room there are less convection currents to transfer the energy from the emitter.
But yeah, allowing airflow is just so self explanatory my kids do understand all this!
You would think if they are going to make a video they would at least put a bit of thought into the message it was to put across.
Maybe they're busy chucking in thousands of heat pumps? Who knows?
Sounds like he shot himself in foot, the lower the flow temperature the better the performance. My Daikin system runs well @ 34C flow.
Edit:- was designed for 45C @ -3.5C external.
I currently run it on flow control set between 34-36C, energy consumption is 400- 650W, with zero cycling other than switching to HWC.
No weather compensation?
@@UpsideDownFork
There's a whole story behind this 🙂
Are we all sitting comfortably.......
Back in February, my HP was installed, like many here I had read as much as I could the previous year into this 'new' technology called heat pumps.
There were a few triggers for me that made me finally decide to jump, one of which was your British Gas install.
Another, perhaps most influential, being the Glyn Hudson self install in his Welsh stone cottage, I thought if it works there it can work anywhere, thus dispelling the myths of the naysayers.
ruclips.net/video/Hyv_vQEvHgo/видео.html
My Daiken 6kW HP sits in a sun trap of a corner; 'all good and well' I thought, additional direct Solar boost.
In practice however the external thermostat resides in the Monoblock unit, Daikin themselves via installation instructions manual ask for an additional thermostat on North facing wall to be fitted (not on my unit), to alleviate the affects of solar gain whereby my unit thinks its 25C, whereas its actually 15C air temperature ( 🥶) when Sun's out.
In practice I tried weather compensation, but cycled too often for my likening, so I thought I would experiment with fixed flow temperature.......
For the bulk of the year (above 3C) the 34C flow seems to give good result, with the input power rising to 518W as I type (3.5C external).
I will see how this fares over winter, and probably poke a stick at weather compensation, for a week or two and see if it fares any better in colder month/weeks.
You can see my data on heatpumpmonitor (Aberdeenshire, other metering, British Gas). The COP is based on the post process 'Carnot COP' simulator, as I do not have an independent flow meter fitted.
However the Daikin control unit reports higher COP value than heatpumpmonitor (I was conservative in choosing a 'practical_efficiency_factor' of 0.45 in 'Carnot COP simulator' (an algorithm that gives a good 'ball park' figure for COP without flow rate (litres/minute).
For avoidance of doubt the Daikin HP has a flow meter, supports full weather compensation, shows flow reading, but data not easily transferrable to Emoncms App', and being own manufacturer the COP value shown on Daikin display may suffer from the 'Diesel gate' syndrome.
@@_Dougaldog Thanks! What's the cost of the additional sensor?
@@UpsideDownFork
I don't know, but a box, digital thermometer, bit of cable, I don't suppose it would be a dear item.
I should really badger BG to fit one, I quite like the results using flow control, outside temperature has just risen above 10C (11.2C) and it's consuming 377 Watts which is the lowest I can get it to run stable at.
I've got the 6kw Daikin in a sunny spot too. I have the 2nd sensor on a north facing wall. It definitely helps.
I don't think his video is that confused, though perhaps the info about weather comp is a bit misleading. I've always understood the design temperature to be the outdoor temperature at which the heat loss for the property has been calculated, nothing to do with the flow temperature, but maybe my understanding is wrong. He's talking about people complaining about the flow temperature they are specifying at that design temperature, and then explaining that this flow temperature is only used at the design temperature. Yes, they could be designing to lower flow temp to achieve the desired room temperatures at the design temp, but as pointed out it seems that may never pay for itself, and would give them many more problem installs (everything they upgrade is another possible point of failure).
Thanks for commenting.
Only 2 days ago, this RUclips video also talked about raising flow temp: "My COP Of My Cosy6 Is Awful How We FIXED It! by Nicolas Raimo"
Thanks. I'm on that one already too!
Yes, Octopus added hydraulic separation. Haven’t seen any updates about the COP though
It's worrying that the professional business has worse communication on this topic than (presuming you aren't doing this full time) an amateur that isn't even in the heat pump trade...
To be honest, in my experience so far, amateurs are often more knowledgeable than heat pump professionals. Mainly because the "pros" have been doing it decades and stuck in their ways. Or are trying to pedal a system which is optimised for the fitter rather than the user. Example being this Octopus misinformation effectively distracting from the truth that they've minimised installation costs at the cost of efficiency, which they think is worth it.
Thank you for the praise.
Yep, just a hobbyist/enthusiast at best!
Seconded. I saw an Artisan electrics video about 'best home batteries', which turned out to be best batteries from the installers' POV, not the customers. And it entirely failed to mention most of the better value options. OK, that's PV/ESS not heat pumps, but same principle. I'm also permanently annoyed that DIYers are excluded from all grants for this stuff. They don't just provide good advice - they often do very good work too. Grants should be based on outcomes/standards, not club memberships.
ruclips.net/video/BP_pqSlh7es/видео.htmlsi=2nfVvNaPYCOWmQ6v same thing here, does not make sense to me. but they suggest the higher flow temp allows it to run for a shorter time with longer off times that compensates for the lower COP of a higher flow. the opposite of what i understand, that low temp over long wins the efficiency game.
I've got some thoughts on that but probably for a separate video.
Compressor can't modulate low enough, circulation pump can't flow enough, perhaps emitters can't shed anymore energy into a modern, well insulated property... it's a recipe for failure.
"Ye canna break the laws of physics Captain" Montgomery Scott to Captain James Tiberius Kirk aboard the starship Enterprise.
👍 Nice!
Terrible video from Octopus. Nick Ramiro repeated this nonsense in his most recent video.😡
@@normanboyes4983 more coming about this 👍