JamesPa

+1 on that conclusion. With a few notable exceptions the Ill designed government schemes appear to be funding the grant harvesting industry, inhibiting new entrants or innovation, and not developing a path to mass adoption at a price people will be willing to pay.

@DanDeehas posted a link to the thread, an 'improved' model appears later in the thread here. It was mostly built to test how important getting the WC curve 'right' is but can be pressed into service for other estimates

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.varmepumpsforum.com/vpforum/index.php%3Faction%3Ddlattach%3Bts%3D1505933467%3Btopic%3D65119.0%3Battach%3D49952&ved=2ahUKEwjkyLf-mKn_AhVDmFwKHX2oAaoQFnoECBMQAQ&usg=AOvVaw0p3Zn86KLVTlAcbi-xHp8j Also referenced upthread, gives an example calculation. So far as I can see weather compensation is not taken into account. If this is correct theoretically one should do a bit better. However real world losses are almost certain to counter this I would think. I posted a few months ago a weather compensation calculator which estimates how much difference various WC algorithms make, using a bin analysis of OATs and published cop. You could dial some figures into this if it helps. Very roughly (from memory), using Mitsubishi COP figures, it's 25% at ft55, 15% at ft 45 and 5% at ft35. Hope that helps somehow.

There is an extract with a discussion on how serr and scop are calculated here. https://www.sciencedirect.com/topics/engineering/seasonal-energy-efficiency-ratio#:~:text=Basically%2C the SCOP calculation method,temperature over a heating season. Still not exactly the exact definition, but closer.

Scrub that thought, it could too easily result in water at ch flow temp being pumped through the dhw cylinder thus cooling it down. It must surely be a diverter valve.

That's what I thought too (and still think), but was wondering if they were relying on the impedance of the ch pump when off to do the same thing.

Well that's that one sorted at least, but I'm curious whether there is a diverter valve or not and if so where this fits. Might be worth checking this too. Also you should be aware that your tiny 4 port buffer tank will certainly be costing you a 10-15 percent increase in consumption during the heating season. There are more intelligent ways to increase system volume if that's the only objective, namely a 2 port buffer and ditch the second pump. However without a full system diagram, making changes could have unexpected knock on effects so it would be inadvisable without getting in someone who knows what they are doing.

I don't know if the vaillant 12kW stretches to 15 but you might need to lie a bit about the construction if it doesn't. MCS as you know requires that the system heat the whole house unless not reasonably practical so if the MCS calculation says 15 they might feel obliged to fit 15+. Obviously this is very installer dependent, hopefully you find a reasonable one. I'm sure you have worked this out yourself by now anyway.

No apology needed, a welcome opportunity for some levity amongst all the serious stuff! As regards the serious stuff, I don't think anyone has seriously disagreed with the challenge with which I initiated this thread. I am awaiting a response from MCS about the flawed nature of their procedures for the majority use case, ie retrofits of properties that have been 'messed around with' (Heat Punk declined to comment). The question is why am I (apparently) the only person talking about it, albeit that lots are talking about the industry failings. Surely this is exactly the sort of thing that the BUS should be stimulating the industry to sort out and, if it isn't achieving that, then what's the point?

Yes, and if I had built the boat myself knowing what I know now, that's probably what I would have done. That said, space is at a premium for accommodating anything staggering (other than the skipper and crew when returning from the pub, that is.)

Good, agreement. It doesn't work for retrofit in a fair number of cases, so far as I am gathering, so it needs to be done differently. Retrofit is the majority market. We build 200k new houses each year and retrofit 1.4M gas boilers, which needs to become 1.4M heat pumps. Sizing them wrongly is a disaster.

To save you reading the whole thread, my 'challenge' quoted below (24/05/2023 at 15:59) is what started it off. Whilst I wouldn't argue with what you say in a straightforward house which is relatively new, un-extended and where the fabric has not been the subject of piecemeal upgrades, I think the problem with your blanket statement is that, in a typical retrofit, there can be lots of unknowns. The infiltration loss is a complete guess and u values of upgraded components are not always known, particularly if they are not visible (eg wall insulation). As a real example my 1930s solid brick house gets a rating by 2 MCS surveyors of 16kW (each after a survey lasting 3 hours). if the calculations are done with the best estimate I have of U-Values, I get to 11kW. The actual measured loss is 7.5kW. The two MCS surveyors ignored the invisible fabric upgrades (I made a point of telling them about them more than once) and I reckon that the reason my calculations still overestimate the load is infiltration loss (I used the MCS assumptions). I hear a similar story far too often and find it difficult not to conclude that the spreadsheets are pseudo-science in many cases (most of our housing stock is older rather than new, and most older houses have had upgrades of some sort done to them so quite likely in most cases). They look impressive but GIGO applies. I have a very strong feeling that the conventional wisdom is fatally flawed in many cases of interest.

You can, I have some insulating the engine compartment of my narrow boat. Unfortunately it's a thermal insulator as well as an absorber of sound.

It sounds like you are, in broad terms, where I am. I now have sufficient confidence, from experiment and calculation, in the actual loss, so know what I want irrespective of the grant harvesters. You seem to be in a similar place. At least you cant now get ripped off for an unsuitable system. If you do end up deferring till next year, I seriously suggest to run it like an ASHP and take lots of readings (easy with gas, you get half hourly meter readings!). So for me its now 'just' a case of finding a way to do what I want, either with or without MCS. Lies about internal wall insulation may help in my case (if anyone will take any notice at all of anything they are told but cant see) together with finding an installer who things out of the box or... I have thought about barriers and/or enclosures. Acoustic enclosures are ridiculously expensive. In my preferred location a screen would look ridiculous, even my LPA agrees with that (even though they suggested it!). There is another possible option, more expensive, but crucially it would only suit a split and few splits are available in this country. I'm still working on technical, or political, options. LPA may be starting to move a bit. I've been in contact with the (Green Party) exec member in charge of planning and separately my (Tory) ward councillor. I think that they genuinely see that something has to be done. Protocol pretty much stops them getting too involved in individual cases but they are talking about using mine as 'an opportunity to learn lessons'. Im not giving up!

OK its basically a small buffer tank which will thus have zero stratification. This will increase your consumption by 10-15%, even assuming that the secondary pump (the one in the CH/DHW loop) is working. If the secondary pump isn't working you wont get much heat to your emitters but you will still waste lots of energy. Without considerable further work its not going to be easy to diagnose fully, I suspect you have multiple problems. But the pump and the buffer tank are a good starting point.

If you think you're going to need pp it might be worth putting in an enquiry with your LPA. Mine is demanding 5dB below night time background (measured at the assessment point) which equates to 25dB(A). That's impossible other than with a split halfway down the garden, which I haven't ruled out but it involves digging up 10 m of path. None of the MCS bods took this into account, but their 16kW monobloc offerings (for my7.5kW house) would require express consent so were in fact all undeliverable within the law Have you got actual meter readings for your house?

That sounds all wrong. Photo please showing this.

That's what I'm thinking, but without a system diagram it's complete guesswork. A lot of energy is apparently going somewhere

How many connections to this? 2, 3 or 4? Do you have/can you create a diagram of how it's all plumbed together.

Didn't you mean On the positive side, having now test driven several electric cars in preparation for when our ICE car finally bites the dust, they are an absolute no brainer once range anxiety is sorted and price parity reached, neither of which is very far off, albeit that it might wipe out the european car industry in the process. They are just better cars. Imagine if electric cars had come first and someone offered you a car powered by a load of small explosions with twice as many parts, poorer acceleration requiring you to visit a special place to fill up with an explosive liquid that pours fumes out the back. Its not going to sell! ASHPs however are a different matter. The technology is there, but we seem to lack the skills or tools to design the system well on a reliable basis, and then we supplement it by cloth eared LPAs like mine that demand unachievable and irrelevant noise specs. Hopefully the likes of Octopus will sort the former out - the grant harvesters and the Government certainly wont. I'm surprised that the ASHP manufacturing industry is not more active in the design/install market.

Fair position I'd say, similar here. Of course we have to be a bit careful blaming China, a proportion of their consumption is really ours as its burned to feed our relentless desire for cheap stuff. We outsourced pollution when we outsourced manufacturing, but that doesn't absolve us of responsibility.

I think the science says that it is guaranteed, had has done for decades. Deny it if you will but the science doesn't care what you or I think. The problem with this argument is that it means everyone waits for everyone else and nothing gets done. My personal bet is that China will eventually sort their emissions better than the west, because they can due to the way their political system works. Either that or their low lying costal communities will get hammered. Of course the Chinese also have form when it comes to unnecessarily sacrificing the lives of their own people.

....because people are still labouring under the misapprehension that tackling climate change wont involve any sacrifices, and weak-willed governments are indulging (arguably encouraging) that fantasy. Had we started properly 20-30 years ago, it might have been possible to adapt without sacrifice. Now it isn't. We will both see devastating effect of climate change (most likely manifested as mass migration and armed conflict) and have to adapt our behaviours to stop it getting even more catastrophic.

This is interesting, but Im still confused. Cold and humid occurs during the season when space heating is needed (here in the South East of England its frankly cold and humid for much of the heating season, sadly, personally Id prefer it were colder and drier). So although I agree that the time at which you heat DHW is adjustable, space heating is less so. Unless you are suggesting offsetting the times of the space heating to avoid the cold/wet periods of the day. I can see you could do this on some days but not every day. Can you clarify your strategy to avoid defrost. Is it basically oversize for the heating load and then run DHW when its not cold and wet? Sadly, for the planet, avoiding 1930 refurbishments isn't an option. Older properties are the majority of our housing stock!

This is a huge bone of contention. This is a huge bone of contention. If an ASHP has been spec'd to go into a dwelling that sympathises with such a unit, then freezing should be deleted? If it's Baltic outside and humid, ergo defrosting is prevalent, then the owner should be heating the DHW by the immersion(s) for that period of the year. The maths defo work out, as I've stated recently, just with the huge labouring of the HP being eradicated, plus the extension to the longevity of the HP / ancillary equipment. Sorry can you explain. I thought that ashps get frost on them when it's around 4 outside and thus humid, because water from the air condenses on them, and that needs to be defrosted from time to time. However dhw is heated the space heating is still needed. Did I miss something?