Nice overview. The heat loss of our house was estimated at 6.1kW. I was bit surprised when the installer recommended a 5kW Valliant heat pump. He was right and the heat pump copes even when the outside temperature dropped to -7C. It also has no problems heating a 300 litre hot water tank to 52C.
Can I ask who your installer was..... And did they fit a buffer tank or a low loss header to your system to balance the lower flow rates of a 5kw Vaillant
@@PeterT-u3xI used a company called VitoEnergy. They’re not cheap and looking back, I think I paid more than I need have. No buffers were needed as I have 15mm pipe to all rads. We have a total 14 rads in a 3 bed detached house. As they were all over 30 years old I decided to upgrade them all (half of which I fitted myself). Some of the rads were designer and the total install was around £21k (from which you can subtract the 7.5k grant).
Comppletely agree! Minimum electrical input is SO important to reduce cycling. A heatpump that is rated to deliver 6KW at -3 will struggle to deliver just 1-2kw of heat input when the weather is milder (spring, autumn). In your example, your Minimum electrical input is say 600w, but in the milder weather (10-15 degrees) you'll be getting a COP of around 5-6, so it's chucking in 3-3.6KW of heat still. If they could modulate down to just a couple of hundred watts, it would save electricity consumption and reduce cycling by trickling in just a KW or 2 of heat when that's all that is needed.
The thing is, it really shouldn't be difficult to calculate. They're already working out heat loss at -2C (delta 23), so can't be hard to then also get a figure at a couple of degrees above the average temperature for your location. That way you have the effective working range, so also know what the real world minimum heat output requirement is. Given that they already know the output figures at various temperatures and flow temperatures, surely it then becomes easier to find the right size that will minimise cycling. In my mind, in a 3D graph you've got a cone that represents operating capabilities, and a line that represents your own heat loss requirements for your individual property. The correct heat pump would see your line stay entirely within the operating range, both at high and low external temperatures.
Do not agree. Minimum electrical input is not SO important to reduce cycling - to reduce cycling minimum heat pumped into the building is SO important to reduce cycling.
@@normanboyes4983 i might be missing something here, but how do you control the heat output without controlling the electrical input, while maintaining COP.
One thing to bear in mind for modulation ratios is that whilst it may be 4:1 at a *given outside temp*, you are most likely to need the lower output at a higher outside temp when the minimum output is higher. So the effective modulation (max output in winter vs min output in late spring) is often closer to 2:1
Brilliant as always. I am bang in the middle of my heat pump journey and all of this information is so useful. Thanks for sharing all your research which must have taken you ages. Jean
I grew up and lived most my life in cold houses. It's fine to have the house get a little cooler when it's below -3 outside. So my strategy is to put a jumper on, cook a meal, and buy a smaller ASHP.
This has been so helpful for my particular situation, I have just bought a 3 bed detached 112 sqm and want to get an installation from Octopus which currently uses the Valliant Aerotherm . I am going to do a loft conversion and possibly a single storey kitchen extension so adding 70 sqm . From your video I am taking the assumption that installing a 7kw now would be able to handle the addition of say 4 room radiators and a bathroom one in the future so I could install now to take advantage of the £7,500 rebate and know it should be able to support future expansion.
Thanks for publishing your heat pump electrical consumption stats. This is particularly useful for me in calculating my battery size to cover not only my normal house load but also the load for my future heat pump installation.
You always say “I’m waffling” 😊 You keep waffling! We are learning plenty thank you 👍Great videos.I genuinely can’t thakyou enough as I’m about to pull the trigger on a heat pump,my biggest issue is 10mm micro bore! 😩
Heatpumpmonitor - should be able to find minimum running input power for most units now, the better performing examples are often sat at that limit 24/7.
From a quick poke around on there the Vaillant 5kw models seems to have a minimum output of around 2kW @ 450w, and the 7kw unit seems to be around 3kW minimum @600w. that was around 12-13°C air temps. This seems to tie in with the specs I could find of 2.1kW and 3.0kW min output for each unit.
Great video, I’m slowly pealing through my onion layers of understanding. I admit I went on trust with my HP Daikin 9kw install with Octopus (which very happy with so far), so I need to go digging first details/data. My primary view of performance is via my Alpha ESS solar battery app, which shows great real time energy use in the house, so I can see real time effects of the HP spooling up and other energy use. Currently most HP energy use - when active - is between 300-800watts. Water heating overnight is biggest jump, can spike briefly at first to above 3kw then quickly settles to around 2kw for most of work. Gaps HP not working clearly larger on milder days. But generally oscillating around 800 watts when working at the moment. This means for me during day even a poor solar day my PV covers all house energy plus HP, battery fills in gaps & gets charged ready for evening heavy use (cookjng/HP). Then 23:30-5:30 cheap rate window i use to top up battery (if needed) keep HP house warm so not working hard first thing next morning, charge EV if needed & any hot water heating. Good solar day (Saturday) I did all this and fed back 19kw to grid - crazy! Not even Summer yet, keeps raining too.
Spot on with this video, oh I wish that the manufactures would ALL have a standard whereby @35° flow they show the output and cop at +7, 0, -3 and -7°C. it would make it a bit easier to pick the correct model. Also it would be useful to show the minimum output at +7°C.
The reason nothing has changed and everything is still being oversized is because MCS regs say your HP must cover ALL heating requirements at -7°C to qualify for the BUS. MCS are not allowed to install a system that might require a little convector or an extra blanket on the three days a year when it is actually that cold. Even though you might have a log burner or storage heater for those coldest days - they have to ignore that. They also ignore any solar gain you might get and funnily enough the sky is usually clear and the sun shining on the very coldest days. You also have heat from the TV, cooking, pets, people, etc - all irrelevant to MCS calcs.
Thanks for commenting! That's not how I read and interpret MCS guidance. From 3.1: "Heat pumps should be selected as closely as possible to the design heat demands. MCS Standard MIS 3005, requires the unit to achieve 100% of the duty at an external temperature condition exceeded for 99.6% of the year, if reasonably practicable. It also stipulates that supplementary heat is not permitted from direct electric at external temperatures above the design external temperature (“bi‐valent point” or “balance point”), but other alternative auxiliary sources of heat are permitted where this is not reasonable practicable in which case the system becomes a ‘hybrid’ system. Although additional supplementary heat may be required when the external temperature drops below the bi‐valent/balance point, this will occur for very short periods of the year and therefore does not significantly affect overall seasonal efficiency even when direct electric heat is utilised. Therefore, heat pumps should be selected as closely as possible to the design demands." In my case the design temp is -1.8 degrees. I don't know where in the UK would design to -7 degrees 🤔 In discussing MCS guidance with installers, unfortunately many think it's the law. This is incorrect. It is guidance.
@@UpsideDownFork The "hybrid systems" you mention are quite extreme cases where maybe the DNO cannot provide enough power or the building is Grade 2 listed and unalterable. Sorry it was late and -7° came off the top of my head, however looking at the MCS spreadsheet to calculate the size of heat pump, the 'outside design temp' is not the same as the 'Post Code degree days'. For example Gatwick area is calculated at -5°C (the baffling spreadsheet cell for this is: LOOKUP(LEFT(C9,2),Post Code Degree Days::Table 1::A3:B126,Post Code Degree Days::Table 1::B3:B126)+IF(AND(G19>90,G19190,G19290,G19390,G19
@@johnhunter4181 Thanks for the additional info! That seems even more crazy. MCS definitely doesn't seem fit for purpose on either the installer or the consumer side of things.
I strongly recommend Toshiba Estia for you. For 8kW pump you get following modulations for 7 deg and above: 1.01, 1.17, 1.28, 1.45. Much better than I've see.
Thanks for the suggestion. Are those figures the electrical input or the power output? In the video I was specifically comparing monobloc units instead or covering some of the split units.
Interesting to see the max inputs. I was wondering if the 3.5kW Vaillant would ever draw more than my inverter can kick out (3.3kW max) and from your 7kW numbers it seems unlikely. Of course, if something else is running at the same time it may well do it.
I'm in the US (Colorado) so my system is very different - ASHP, air handler and air ducts throughout the house. I have seen the heat pump come close to its rated maximum input power but at 10C below the design temp (-18C here). Those days were big outliers on my data. Other people in my area with similar installs added supplementary heat and/or turned down the thermostat for those days. Our house is about the same size but the temperature swings here so much, my heat pump is 14kW and probably only a little oversized.
This was the right video at the right time for me, thanks! I am getting quotes atm and have been struggling to understand why the heat pumps recommended have varied so much, from 7kw to 12. The 12kw Samsung pump that one company has recommended seems high to me given our heat loss of 6.5kw. But the company has generally been very good and thorough so i am inclined to trust. My concern is less that they've got it wrong and more that they're just being over cautious. In reality we only heat the house to 19 so am concerned about a pump that is pretty oversized and ends up cycling a lot. Plus it's a chunky beast! Anyway, I'm waffling...
12Kw seems insane for this to me. I just got a Vaillant A+ 7Kw in a 3 bed detached in Scotland (we design temp to -4 not -2 like most of England) with a loss of 5.5Kw, floor area 110m2. Even then it seems oversized slightly as I'm now running steady-state heating and the rads are positively tepid until we get down below about 3 degrees, but we're planning on extensions a little later in the lifespan of the unit so I don't mind it being larger to account for that. Short term cops of 4.5 - 5 when it's been 3-7 degrees mostly lately, which is great. So to me, it sounds beyond cautious, it sounds a little bit like gas thinking to me.
@@MacCraig8 to be fair, I think Samsungs are quite different to Vaillants. The Vaillant 7kW is based on -5 degrees outside and 55 degree flow, whereas the Samsung 12kW is based on 7 degrees outside and 35 degree flow. At our design temp (-3.4) the 12kW Samsung only outputs about 9.5kW based on 50 degree flow. That's still too high for our heat loss, but perhaps it's not as crazy as it first seems.
@@chrismckee2799Gotcha, still think a near 50% headroom is perhaps still not in your best interests, unless like myself, considering future extensions within the life of the unit. Not to mention if it's one of those double fan towerblocks I'd be keen to see if I could stick to a single personally, far less asthetically awkward on a relatively normal house. Genuinely think the oversize bias with oversized visuals help the misinformationists point and go 'look how rediculous!'
I faced with the same difficulties when I looked at pumps suitable for my house I do confirm that it is very hard to find useful info, when you want to know more than the basic info (in Italy the law is to inform about power output and COP at 7°C OT and 35°C delivery flow, and also at 45°C flow. Typically you must be an installation company to have access at more data (at least on the italian website, but I cannot access any other). More data are available to everybody from LG for their R32 ThermaV Monobloc S versions, even if I feel that some info is possibly not accurate. I compared the three units that are rated 12, 14 and 16 W (at -15°C, while operation down to -25 is possible with reduced output), which are certainly the same machine assembly with just a different tuning: on paper they are rated for modulation down to 11 to 13% (and the circulating pump down to 10%), but I could not find much info of what the COP will be at those low power output. There is however a table suggesting data for a "typical" system at various external temperatures: interestingly, as the power output is reduced, the COP gets better. Among the three units (of the same construction) the lower power are slightly more efficient. On the user manual of the same units you have many different control options: e.g. you can select the deltaT, or even the circulation pump speed, if I correctly remember, which should allow you force the heat pump to operate at different power outputs, at a given temperature (but this is my theoretical understanding).
@@UpsideDownFork thanks, I have watched the video; I also found the video from heatgeek on the LG pump, assuming it is the one on the noisy fan. If it is that one, I cannot agree on what is stated regarding relevant performance from the data sheet. However, my reference to that pump was relevant to the capability at reduced loads, which I read to be as low as 10/15%, much lower than what is elsewhere stated. I had not looked at the Vaillant pumps, as they are not so popular in y country: from a quick look at their powerful versions, it seems to me that also these are same construction with different tuning, the more powerful being less efficient. Wonder if you can share my understanding on this, I say feeling because I am not aware of details of the theory of these machines. Is it true that a unit tuned for higher output has a lower COP, at same ambient and delivery temperatures, etc.? Is it true that, as load is lowered, the COP gets higher (to some extent)? Does this mean that in a family of pumps the lower power units are more efficient, while probably have a reduced range at low output? One would need to have the full data from the manufacturer. My next concern is the design temperature: in my area this is -5°C by law and, while this never occurred recently, I remember a full January below this in 1985, with a full week below -15: at that time it was just a big oil consumption; one would have to design the heat pump for a higher power and at a lower temperature, or prepare with alternate sources.
I have found the Mitsubishi information the best of the bunch for those who really want to go into the details; the Ecodan A2W Databook has masses of information (min/part-load/max power output at 5 deg C increments of air and water temperatures). However, yes their two-page data-sheet is a bit weak.
I decided not to go with Octopus as they would only put in Daikin ASHP's. Anecdotally it looked like the minimum daikin running elec consumption was higher than the Vaillants plus integration/API's seems better with Vaillant. Any thoughts/comments ASHP guru's?
8kW Daikin Altherma 3 installed by octopus seems to be a good unit. Many performing very well. Have a look here: heatpumpmonitor.org/system/view?id=72 If anything, the minimum modulation looks better than the Vaillant. Daikin has good bus integration if you are looking into home assistant then it has as much, if not more support that the equivalent Vaillant. TLDR: You're splitting hairs, unless you are looking at different size of units.
Thanks, I’d also been looking at the first three models and only the Vaillant seems to quote real figures across different temps and so 7kW would be the nominal with a bit extra unlike the others where the figures are just fingers in the air…
We are in the process of getting a heat pump from Octopus our heat loss in the house is 6.5kw. Octopus initially specified the 9kw Daikin however the 9kw HP has a minimum electrical input of 950w where as the 8kw heat pumps minimum electrical input is 325w a massive difference that ultimately would have cost me on my bills. Discussed with Octopus and they were happy to change the HP to the 8kw. Apparently the 4,6 and 8kw HP are all exactly the same the first two are limited by software only so it makes sense that they all take the same amount of electricity to run them at the lower output end. Again the 9,11,13 and 16kw units are all the same unit thus the reason why there is such a difference in minimum electrical input between 8 and 9kw units.
I have the 11kw and it can run much lower than 950w. The other day I could see on our smart meter the hole house consumption was showing 844w. The compressor was running so to see how much it was using I tuned the pump off. The house consumption dropped to 84w. That means the ASHP was using 760w. Still not as low as 325w but at most, on mild days. it will only cycle about 7 time in a day and our SCOP is 4.3
The Vaillant max power input numbers do seem to be available on the "Installation and maintenance instructions" PDF on page 46 not sure what the external design temp is probably -2 or -3 is my guess I contacted my DNO recently and even they thought 7kW was peak electrical power input so it's not just consumers
Maybe the 3.5 kw pump would have been the most efficient would be undersized at 70% as some dedicated software recommends. Nothing is lost and I recommend trying to find the temperature at which the pump stops cycling and heating to different temperatures during the day. It is now oversized only for 24/24 use but not for 12/24 or even less hours of operation.
Interesting video, I am assuming that as that energy demand drops you will be along the heat curve and therefore the flow temp will be lower, that again increases COP and doesn't help the low modulation. I did have the chance to get a 5kw arotherm, but went for the 7kw as my heat loss is 7.6kw at -3. Ouu by the way second hand pumps can be had , lol. I have my 7kw, as its DIY, I am putting in 35mm primary and twin mag and y strainers, because I can.
Welcome to the world of the "Ratings Game". It has always been the case that AC & Heat Pump manufacturers rate & produce performance data to show their products in the best possible light. Car makers do exactly the same with prescribed fuel consumption test procedures under lab conditions, which as we all know, bares no resemblance to real world results because replicating real world conditions for different types of drivers & ways of driving is impossible to achieve. The same is true for Heat Pumps. Interestingly, Air to Air split heat pumps have long since shown minimum & maximum heat/cool capacities & power input data for different models (at least the manufacturers that I was involved with did). However, the temperatures (inside & outside) that were used to generate this data could vary widely so once again there is plenty of opportunity to "manipulate the numbers". And, as you have found, the same is true for ATW products. In an effort to make comparisons between different makes more easy industry bodies require individual heat pump models to be tested & rated at specific conditions. This can be done in-house at the manufacturers factories providing their facilities meet the governing bodies test, measuring equipment & procedural standards. Governing bodies will visit & witness the manufacturers testing facilities to ensure their compliance. Governing bodies will also do spot checks by testing randomly selected / purchased heat pumps & test them in its own lab facilities. In the UK the most well known of these test houses is BSRIA who I had dealings with when I worked for two different heat pump manufacturers. This data is also used for the energy labels attached to each product. That said it is still not easy to do meaningful comparisons between manufacturers when there are so many installation variables that can affect the overall system performance e.g. the type of emitters used, the pipe sizes, lengths of pipe & pressure losses, pump sizes, buffer tanks or not etc etc. To combat this most ATW manufacturers should publish a "short form" of capacity & power input product rating based rads or UFH & different flow temps. This is typically shown in their sales catalogues & should be the same format for each make in an attempt to level the playing field. Whilst not totally accurate it can be used as as a quick way of comparing different makes. However, for all the reasons stated above accurate comparisons between makes are almost impossible due to the many variables involved. Last but not least, oversizing of heat pumps is still fairly common & is a hangover from the days of boilers when sizing was, how should I say, more of a guesstimate than a science. It's far better to slightly undersize a heat pump that to oversize it. Now I'm waffling so I'll stop!!!!!
Totally not relevant to heat pumps, but you might be surprised that the electrical consumption of a microwave is typically about double what the rated cooking output is, and they run at 100% duty cycle.
Hello. Isn’t the 7 kW arotherm plus rated ussually at w35? At A-5/W35, it generates more like 8,2kW. Why do you compare -5/W55 with others at W35 and 45?
Where can I find the 4 to 1 modulation data for Vaillant ASHPs you mention in the video.... Have I wrongly assumed that Vaillant low modulation was simply a ratio of the minimum & maximum l/h flow rates which is closer to 2 to 1.
Looking at their tables it seems to suggest that there's no modulation whatsoever; output goes up at higher temperatures with the same quoted COP. If output dropped and COP remained the same as temperature increased, then this would indicate modulation.
To be fair, the calculations and the MCS requirements are complex. If I was an electrician or a plumber I'd just prefer to use a bunch of rules of thumb and avoid the paperwork. I'm pretty sure that a 5kW heat pump will be fine for my house (based on detailed calculations and closely monitoring my current gas system) but I suspect that I'll be quoted 7kW and above when the plumbers come round this week. There's no incentive for a plumber to quote a smaller system - less money overall and a greater chance of a customer call-back when they're too cold.
Still learning about heat pumps so sorry if I get things wrong , I did hear that there’s a new refrigerated system that is coming in by Jan 2025 I think it’s part of the in coming law or requirements within the industry, heard about this the other day , did I get it wrong or should I cut down on the whiskey.
Not sure if you can help , I am having two pumps and installer is quoting for two Mitsubishi ecodans labelled 11kw . From what I am reading Vaillants would be preferable all round , agree or disagree?
Thanks , I have , they were teetering on the verge of would two 9kw types do . However given the refurbishment nature where by there is such a mix of new and old and the incomplete nature of the build , we are trying to insulate further any old walls left , putting as much as possible into new roof plus insulated reflective felt and triple glaze , it’s probably a nightmare to calculate accurately , the rooms are sizeable and there is a three floor entrance atrium to make matters worse , sounds grand but it’s not it’s just my idiotic design , I didn’t pay for a whizzy architect.
Nice overview. The heat loss of our house was estimated at 6.1kW. I was bit surprised when the installer recommended a 5kW Valliant heat pump. He was right and the heat pump copes even when the outside temperature dropped to -7C. It also has no problems heating a 300 litre hot water tank to 52C.
Can I ask who your installer was..... And did they fit a buffer tank or a low loss header to your system to balance the lower flow rates of a 5kw Vaillant
@@PeterT-u3xI used a company called VitoEnergy. They’re not cheap and looking back, I think I paid more than I need have. No buffers were needed as I have 15mm pipe to all rads. We have a total 14 rads in a 3 bed detached house. As they were all over 30 years old I decided to upgrade them all (half of which I fitted myself). Some of the rads were designer and the total install was around £21k (from which you can subtract the 7.5k grant).
@@PeterT-u3xVitoEnergy. No buffers or zones
@@PeterT-u3xVito energy. No buffers or zones.
Probably even the 3.5 kw version shown in the video would have been the most efficient.
Comppletely agree! Minimum electrical input is SO important to reduce cycling. A heatpump that is rated to deliver 6KW at -3 will struggle to deliver just 1-2kw of heat input when the weather is milder (spring, autumn). In your example, your Minimum electrical input is say 600w, but in the milder weather (10-15 degrees) you'll be getting a COP of around 5-6, so it's chucking in 3-3.6KW of heat still. If they could modulate down to just a couple of hundred watts, it would save electricity consumption and reduce cycling by trickling in just a KW or 2 of heat when that's all that is needed.
The thing is, it really shouldn't be difficult to calculate. They're already working out heat loss at -2C (delta 23), so can't be hard to then also get a figure at a couple of degrees above the average temperature for your location. That way you have the effective working range, so also know what the real world minimum heat output requirement is.
Given that they already know the output figures at various temperatures and flow temperatures, surely it then becomes easier to find the right size that will minimise cycling.
In my mind, in a 3D graph you've got a cone that represents operating capabilities, and a line that represents your own heat loss requirements for your individual property.
The correct heat pump would see your line stay entirely within the operating range, both at high and low external temperatures.
Do not agree. Minimum electrical input is not SO important to reduce cycling - to reduce cycling minimum heat pumped into the building is SO important to reduce cycling.
@@normanboyes4983 i might be missing something here, but how do you control the heat output without controlling the electrical input, while maintaining COP.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
One thing to bear in mind for modulation ratios is that whilst it may be 4:1 at a *given outside temp*, you are most likely to need the lower output at a higher outside temp when the minimum output is higher. So the effective modulation (max output in winter vs min output in late spring) is often closer to 2:1
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Brilliant as always. I am bang in the middle of my heat pump journey and all of this information is so useful. Thanks for sharing all your research which must have taken you ages. Jean
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Simply brilliant ...'not going to waffle'....one for the Heat Geeks to note. Simple, clear and informative. Totally enlightening.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
At around 11.10 think you say output meaning input a couple of times. Still understandable . Good video. Same journey we have been on.
I grew up and lived most my life in cold houses. It's fine to have the house get a little cooler when it's below -3 outside.
So my strategy is to put a jumper on, cook a meal, and buy a smaller ASHP.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Thanks for the info. The main thing that puts me off is noise levels particularly overnight.
If your indoor fridge / freezer keeps you awake at night, then perhaps an outside ASHP is not for you....😴
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
This has been so helpful for my particular situation, I have just bought a 3 bed detached 112 sqm and want to get an installation from Octopus which currently uses the Valliant Aerotherm . I am going to do a loft conversion and possibly a single storey kitchen extension so adding 70 sqm . From your video I am taking the assumption that installing a 7kw now would be able to handle the addition of say 4 room radiators and a bathroom one in the future so I could install now to take advantage of the £7,500 rebate and know it should be able to support future expansion.
I didn't know Octopus use Vaillant now. I think they used to use Daikin.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Thanks for publishing your heat pump electrical consumption stats. This is particularly useful for me in calculating my battery size to cover not only my normal house load but also the load for my future heat pump installation.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
You always say “I’m waffling” 😊 You keep waffling! We are learning plenty thank you 👍Great videos.I genuinely can’t thakyou enough as I’m about to pull the trigger on a heat pump,my biggest issue is 10mm micro bore! 😩
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Heatpumpmonitor - should be able to find minimum running input power for most units now, the better performing examples are often sat at that limit 24/7.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
From a quick poke around on there the Vaillant 5kw models seems to have a minimum output of around 2kW @ 450w, and the 7kw unit seems to be around 3kW minimum @600w. that was around 12-13°C air temps. This seems to tie in with the specs I could find of 2.1kW and 3.0kW min output for each unit.
Great video, I’m slowly pealing through my onion layers of understanding. I admit I went on trust with my HP Daikin 9kw install with Octopus (which very happy with so far), so I need to go digging first details/data. My primary view of performance is via my Alpha ESS solar battery app, which shows great real time energy use in the house, so I can see real time effects of the HP spooling up and other energy use. Currently most HP energy use - when active - is between 300-800watts. Water heating overnight is biggest jump, can spike briefly at first to above 3kw then quickly settles to around 2kw for most of work. Gaps HP not working clearly larger on milder days. But generally oscillating around 800 watts when working at the moment. This means for me during day even a poor solar day my PV covers all house energy plus HP, battery fills in gaps & gets charged ready for evening heavy use (cookjng/HP). Then 23:30-5:30 cheap rate window i use to top up battery (if needed) keep HP house warm so not working hard first thing next morning, charge EV if needed & any hot water heating. Good solar day (Saturday) I did all this and fed back 19kw to grid - crazy! Not even Summer yet, keeps raining too.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Well done in producing this. It would need Government intervention to specify a standard rating and specification across manufacturers.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Thanks also for this explanation as I was thinking exactly the rating was the consumption max.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Spot on with this video, oh I wish that the manufactures would ALL have a standard whereby @35° flow they show the output and cop at +7, 0, -3 and -7°C. it would make it a bit easier to pick the correct model. Also it would be useful to show the minimum output at +7°C.
Thanks for your comment. I've replied in this video: ruclips.net/video/u6J-Ba-6-jI/видео.html
The reason nothing has changed and everything is still being oversized is because MCS regs say your HP must cover ALL heating requirements at -7°C to qualify for the BUS. MCS are not allowed to install a system that might require a little convector or an extra blanket on the three days a year when it is actually that cold. Even though you might have a log burner or storage heater for those coldest days - they have to ignore that. They also ignore any solar gain you might get and funnily enough the sky is usually clear and the sun shining on the very coldest days. You also have heat from the TV, cooking, pets, people, etc - all irrelevant to MCS calcs.
Thanks for commenting!
That's not how I read and interpret MCS guidance.
From 3.1:
"Heat pumps should be selected as closely as
possible to the design heat demands. MCS
Standard MIS 3005, requires the unit to achieve
100% of the duty at an external temperature
condition exceeded for 99.6% of the year, if
reasonably practicable. It also stipulates that
supplementary heat is not permitted from direct
electric at external temperatures above the design
external temperature (“bi‐valent point” or “balance
point”), but other alternative auxiliary sources of
heat are permitted where this is not reasonable
practicable in which case the system becomes a
‘hybrid’ system.
Although additional supplementary heat may be
required when the external temperature drops
below the bi‐valent/balance point, this will occur
for very short periods of the year and therefore
does not significantly affect overall seasonal
efficiency even when direct electric heat is utilised.
Therefore, heat pumps should be selected as
closely as possible to the design demands."
In my case the design temp is -1.8 degrees. I don't know where in the UK would design to -7 degrees 🤔
In discussing MCS guidance with installers, unfortunately many think it's the law. This is incorrect. It is guidance.
@@UpsideDownFork The "hybrid systems" you mention are quite extreme cases where maybe the DNO cannot provide enough power or the building is Grade 2 listed and unalterable. Sorry it was late and -7° came off the top of my head, however looking at the MCS spreadsheet to calculate the size of heat pump, the 'outside design temp' is not the same as the 'Post Code degree days'. For example Gatwick area is calculated at -5°C (the baffling spreadsheet cell for this is: LOOKUP(LEFT(C9,2),Post Code Degree Days::Table 1::A3:B126,Post Code Degree Days::Table 1::B3:B126)+IF(AND(G19>90,G19190,G19290,G19390,G19
@@johnhunter4181 Thanks for the additional info! That seems even more crazy. MCS definitely doesn't seem fit for purpose on either the installer or the consumer side of things.
I strongly recommend Toshiba Estia for you. For 8kW pump you get following modulations for 7 deg and above: 1.01, 1.17, 1.28, 1.45. Much better than I've see.
Thanks for the suggestion. Are those figures the electrical input or the power output?
In the video I was specifically comparing monobloc units instead or covering some of the split units.
@@UpsideDownForkThese are the kW of power outputs. I can guarantee that this is the best HP if you don't wish to pay for oversized 300L heat buffer.
@@BartoszBielecki thanks very much. Are you in the UK?
Interesting to see the max inputs. I was wondering if the 3.5kW Vaillant would ever draw more than my inverter can kick out (3.3kW max) and from your 7kW numbers it seems unlikely. Of course, if something else is running at the same time it may well do it.
Even the hot water cycle peaks at between 2-2.5kW, depending on outside temperature.
You'll be fine 👍
I'm in the US (Colorado) so my system is very different - ASHP, air handler and air ducts throughout the house. I have seen the heat pump come close to its rated maximum input power but at 10C below the design temp (-18C here). Those days were big outliers on my data. Other people in my area with similar installs added supplementary heat and/or turned down the thermostat for those days. Our house is about the same size but the temperature swings here so much, my heat pump is 14kW and probably only a little oversized.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
This was the right video at the right time for me, thanks! I am getting quotes atm and have been struggling to understand why the heat pumps recommended have varied so much, from 7kw to 12. The 12kw Samsung pump that one company has recommended seems high to me given our heat loss of 6.5kw. But the company has generally been very good and thorough so i am inclined to trust. My concern is less that they've got it wrong and more that they're just being over cautious. In reality we only heat the house to 19 so am concerned about a pump that is pretty oversized and ends up cycling a lot. Plus it's a chunky beast! Anyway, I'm waffling...
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
12Kw seems insane for this to me. I just got a Vaillant A+ 7Kw in a 3 bed detached in Scotland (we design temp to -4 not -2 like most of England) with a loss of 5.5Kw, floor area 110m2.
Even then it seems oversized slightly as I'm now running steady-state heating and the rads are positively tepid until we get down below about 3 degrees, but we're planning on extensions a little later in the lifespan of the unit so I don't mind it being larger to account for that. Short term cops of 4.5 - 5 when it's been 3-7 degrees mostly lately, which is great.
So to me, it sounds beyond cautious, it sounds a little bit like gas thinking to me.
@@MacCraig8 to be fair, I think Samsungs are quite different to Vaillants. The Vaillant 7kW is based on -5 degrees outside and 55 degree flow, whereas the Samsung 12kW is based on 7 degrees outside and 35 degree flow. At our design temp (-3.4) the 12kW Samsung only outputs about 9.5kW based on 50 degree flow. That's still too high for our heat loss, but perhaps it's not as crazy as it first seems.
@@chrismckee2799Gotcha, still think a near 50% headroom is perhaps still not in your best interests, unless like myself, considering future extensions within the life of the unit. Not to mention if it's one of those double fan towerblocks I'd be keen to see if I could stick to a single personally, far less asthetically awkward on a relatively normal house. Genuinely think the oversize bias with oversized visuals help the misinformationists point and go 'look how rediculous!'
I faced with the same difficulties when I looked at pumps suitable for my house I do confirm that it is very hard to find useful info, when you want to know more than the basic info (in Italy the law is to inform about power output and COP at 7°C OT and 35°C delivery flow, and also at 45°C flow. Typically you must be an installation company to have access at more data (at least on the italian website, but I cannot access any other). More data are available to everybody from LG for their R32 ThermaV Monobloc S versions, even if I feel that some info is possibly not accurate. I compared the three units that are rated 12, 14 and 16 W (at -15°C, while operation down to -25 is possible with reduced output), which are certainly the same machine assembly with just a different tuning: on paper they are rated for modulation down to 11 to 13% (and the circulating pump down to 10%), but I could not find much info of what the COP will be at those low power output. There is however a table suggesting data for a "typical" system at various external temperatures: interestingly, as the power output is reduced, the COP gets better. Among the three units (of the same construction) the lower power are slightly more efficient.
On the user manual of the same units you have many different control options: e.g. you can select the deltaT, or even the circulation pump speed, if I correctly remember, which should allow you force the heat pump to operate at different power outputs, at a given temperature (but this is my theoretical understanding).
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
@@UpsideDownFork thanks, I have watched the video; I also found the video from heatgeek on the LG pump, assuming it is the one on the noisy fan. If it is that one, I cannot agree on what is stated regarding relevant performance from the data sheet. However, my reference to that pump was relevant to the capability at reduced loads, which I read to be as low as 10/15%, much lower than what is elsewhere stated. I had not looked at the Vaillant pumps, as they are not so popular in y country: from a quick look at their powerful versions, it seems to me that also these are same construction with different tuning, the more powerful being less efficient.
Wonder if you can share my understanding on this, I say feeling because I am not aware of details of the theory of these machines. Is it true that a unit tuned for higher output has a lower COP, at same ambient and delivery temperatures, etc.? Is it true that, as load is lowered, the COP gets higher (to some extent)? Does this mean that in a family of pumps the lower power units are more efficient, while probably have a reduced range at low output?
One would need to have the full data from the manufacturer.
My next concern is the design temperature: in my area this is -5°C by law and, while this never occurred recently, I remember a full January below this in 1985, with a full week below -15: at that time it was just a big oil consumption; one would have to design the heat pump for a higher power and at a lower temperature, or prepare with alternate sources.
@@enzofraschini7117 Your theory sounds like a good one to me.
I have found the Mitsubishi information the best of the bunch for those who really want to go into the details; the Ecodan A2W Databook has masses of information (min/part-load/max power output at 5 deg C increments of air and water temperatures). However, yes their two-page data-sheet is a bit weak.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
I decided not to go with Octopus as they would only put in Daikin ASHP's. Anecdotally it looked like the minimum daikin running elec consumption was higher than the Vaillants plus integration/API's seems better with Vaillant. Any thoughts/comments ASHP guru's?
8kW Daikin Altherma 3 installed by octopus seems to be a good unit. Many performing very well. Have a look here: heatpumpmonitor.org/system/view?id=72
If anything, the minimum modulation looks better than the Vaillant.
Daikin has good bus integration if you are looking into home assistant then it has as much, if not more support that the equivalent Vaillant.
TLDR: You're splitting hairs, unless you are looking at different size of units.
Thanks, I’d also been looking at the first three models and only the Vaillant seems to quote real figures across different temps and so 7kW would be the nominal with a bit extra unlike the others where the figures are just fingers in the air…
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
We are in the process of getting a heat pump from Octopus our heat loss in the house is 6.5kw. Octopus initially specified the 9kw Daikin however the 9kw HP has a minimum electrical input of 950w where as the 8kw heat pumps minimum electrical input is 325w a massive difference that ultimately would have cost me on my bills. Discussed with Octopus and they were happy to change the HP to the 8kw.
Apparently the 4,6 and 8kw HP are all exactly the same the first two are limited by software only so it makes sense that they all take the same amount of electricity to run them at the lower output end. Again the 9,11,13 and 16kw units are all the same unit thus the reason why there is such a difference in minimum electrical input between 8 and 9kw units.
I have the 11kw and it can run much lower than 950w. The other day I could see on our smart meter the hole house consumption was showing 844w. The compressor was running so to see how much it was using I tuned the pump off. The house consumption dropped to 84w. That means the ASHP was using 760w. Still not as low as 325w but at most, on mild days. it will only cycle about 7 time in a day and our SCOP is 4.3
@@bryanhindle8307 is it an EDLA monoblock? The refridgerent split and hydrosplit units are different, my hydrosplit 11kW drops to 650W or so...
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
The Vaillant max power input numbers do seem to be available on the "Installation and maintenance instructions" PDF on page 46 not sure what the external design temp is probably -2 or -3 is my guess
I contacted my DNO recently and even they thought 7kW was peak electrical power input so it's not just consumers
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
@@UpsideDownFork Cheers I watched live :)
Maybe the 3.5 kw pump would have been the most efficient would be undersized at 70% as some dedicated software recommends.
Nothing is lost and I recommend trying to find the temperature at which the pump stops cycling and heating to different temperatures during the day.
It is now oversized only for 24/24 use but not for 12/24 or even less hours of operation.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Interesting video, I am assuming that as that energy demand drops you will be along the heat curve and therefore the flow temp will be lower, that again increases COP and doesn't help the low modulation. I did have the chance to get a 5kw arotherm, but went for the 7kw as my heat loss is 7.6kw at -3. Ouu by the way second hand pumps can be had , lol. I have my 7kw, as its DIY, I am putting in 35mm primary and twin mag and y strainers, because I can.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Welcome to the world of the "Ratings Game".
It has always been the case that AC & Heat Pump manufacturers rate & produce performance data to show their products in the best possible light. Car makers do exactly the same with prescribed fuel consumption test procedures under lab conditions, which as we all know, bares no resemblance to real world results because replicating real world conditions for different types of drivers & ways of driving is impossible to achieve. The same is true for Heat Pumps.
Interestingly, Air to Air split heat pumps have long since shown minimum & maximum heat/cool capacities & power input data for different models (at least the manufacturers that I was involved with did). However, the temperatures (inside & outside) that were used to generate this data could vary widely so once again there is plenty of opportunity to "manipulate the numbers". And, as you have found, the same is true for ATW products.
In an effort to make comparisons between different makes more easy industry bodies require individual heat pump models to be tested & rated at specific conditions. This can be done in-house at the manufacturers factories providing their facilities meet the governing bodies test, measuring equipment & procedural standards. Governing bodies will visit & witness the manufacturers testing facilities to ensure their compliance. Governing bodies will also do spot checks by testing randomly selected / purchased heat pumps & test them in its own lab facilities. In the UK the most well known of these test houses is BSRIA who I had dealings with when I worked for two different heat pump manufacturers. This data is also used for the energy labels attached to each product.
That said it is still not easy to do meaningful comparisons between manufacturers when there are so many installation variables that can affect the overall system performance e.g. the type of emitters used, the pipe sizes, lengths of pipe & pressure losses, pump sizes, buffer tanks or not etc etc. To combat this most ATW manufacturers should publish a "short form" of capacity & power input product rating based rads or UFH & different flow temps. This is typically shown in their sales catalogues & should be the same format for each make in an attempt to level the playing field. Whilst not totally accurate it can be used as as a quick way of comparing different makes. However, for all the reasons stated above accurate comparisons between makes are almost impossible due to the many variables involved.
Last but not least, oversizing of heat pumps is still fairly common & is a hangover from the days of boilers when sizing was, how should I say, more of a guesstimate than a science. It's far better to slightly undersize a heat pump that to oversize it.
Now I'm waffling so I'll stop!!!!!
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Totally not relevant to heat pumps, but you might be surprised that the electrical consumption of a microwave is typically about double what the rated cooking output is, and they run at 100% duty cycle.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Hello. Isn’t the 7 kW arotherm plus rated ussually at w35? At A-5/W35, it generates more like 8,2kW. Why do you compare -5/W55 with others at W35 and 45?
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
So much cycling. Definitely got an oversized heat pump.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Where can I find the 4 to 1 modulation data for Vaillant ASHPs you mention in the video.... Have I wrongly assumed that Vaillant low modulation was simply a ratio of the minimum & maximum l/h flow rates which is closer to 2 to 1.
Looking at their tables it seems to suggest that there's no modulation whatsoever; output goes up at higher temperatures with the same quoted COP.
If output dropped and COP remained the same as temperature increased, then this would indicate modulation.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
To be fair, the calculations and the MCS requirements are complex. If I was an electrician or a plumber I'd just prefer to use a bunch of rules of thumb and avoid the paperwork. I'm pretty sure that a 5kW heat pump will be fine for my house (based on detailed calculations and closely monitoring my current gas system) but I suspect that I'll be quoted 7kW and above when the plumbers come round this week. There's no incentive for a plumber to quote a smaller system - less money overall and a greater chance of a customer call-back when they're too cold.
Rules of thumb are rules of dumb. It is essential to fully understand the specification in detail there are no shortcuts.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Still learning about heat pumps so sorry if I get things wrong , I did hear that there’s a new refrigerated system that is coming in by Jan 2025 I think it’s part of the in coming law or requirements within the industry, heard about this the other day , did I get it wrong or should I cut down on the whiskey.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Can I ask where you get the usage info around 12.00 into this. We also have vaillant Arotherm.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
Not sure if you can help , I am having two pumps and installer is quoting for two Mitsubishi ecodans labelled 11kw .
From what I am reading Vaillants would be preferable all round , agree or disagree?
Have you had a proper heat loss survey, done? As 2x11kW seems pretty extreme.
Thanks , I have , they were teetering on the verge of would two 9kw types do .
However given the refurbishment nature where by there is such a mix of new and old and the incomplete nature of the build , we are trying to insulate further any old walls left , putting as much as possible into new roof plus insulated reflective felt and triple glaze , it’s probably a nightmare to calculate accurately , the rooms are sizeable and there is a three floor entrance atrium to make matters worse , sounds grand but it’s not it’s just my idiotic design , I didn’t pay for a whizzy architect.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html
They manufactures need to do a lot better with modulation, problem is we need more awareness. I’ll probably keep my 10:1 boiler until they do better.
Thanks for the comment. I've responded in this video: ruclips.net/video/BQQ5cOFCjKI/видео.html