You can do your own heat loss, it's very easy. There is a sheet in my signature you can use to your hearts content!

@grahamb
I think you are correct. Unless you have a modern well insulated house, solar and batteries, the heat pump system is a huge gamble.
The heat loss fraud can be done by three different suppliers and you will get three differenct results... and then they will bear no resemblance to performance (and it says so in the small font footnotes at the bottom of the page).
I really would have liked to get away from heating the planet while trying to heat our home but we are reluctantly, very reluctantly looking at removing the heat pump and replacing with LPG.

@jswhite, I’m working on a ‘process’ for homeowners to follow on how to get bodged systems fixed/rectified, which I’ll hopefully publish soon and hopefully this will give consumers a step-by-step guide to follow.

Posted by: @batalto

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You can do your own heat loss, it's very easy. There is a sheet in my signature you can use to your hearts content!

Thank you. I've downloaded a copy to take a look.

Posted by: @jswhite

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I think you are correct. Unless you have a modern well insulated house, solar and batteries, the heat pump system is a huge gamble.

I have to suggest that, while anecdotally there may be accounts that suggest this is the case, in fact it is a myth.

We need to separate fact from fiction here, and look at the real world and what happens in it. In practice, there is a bias towards old leaky building getting bad installations, but it doesn't have to be that way.

1. Heat loss calculations are not easy, they are tedious and boring and you need to concentrate and spend a lot of time to get things right. This is why installers cut corners and get things wrong. Among the heat loss calcs done for me by installers, some were pure fantasy (one appeared to have been done by a blind surveyor, and this from a company with a full on 'leave it to the professionals' strapline) and others had silly mistakes (typos, entering 2.3 instead of 12.3 sort of thing) and some made wild assumptions eg reduced the house to a single giant shoe box and did the heat loss for that. No wonder they all came out with different results. But done correctly, they will give you a reasonable estimate of the heat loss. What you do is measure all the relevant areas (walls windows doors floors and ceilings etc) which is very tedious and boring to do, and then apply, from standard tables, the heat loss in watts per degree centigrade per square metre to each area and sum (add up) all the losses to get a total loss, and then add in an allowance for air changes (a sealed room has less air changes than a kitchen with an often opened back door) and that's pretty much it, apart from some minor refinements. There are plenty of freely available spreadsheets available that are set up to do the calcs for you, you don't have to set up the formulas, you just enter the measurements for each room, and the better ones even have drop down boxes with U values (the loss in watts per degree per area) for common building materials. You will nonetheless have lost several hours of your life that you will never get back, but you will know your heat loss.

2. No heat source cares one iota about what it is heating. To any boiler or heat pump, there is nothing special about heat pumps in this, a huge well insulated mansion of ten bedrooms on the South Coast of England with a total heat loss of 10kW is no different to a battered old leaky tiny crofter's cottage in the Highlands of Scotland with a total heat loss of 10kW. In each case, under steady state conditions, which is what you are aiming for, each building loses 10kW, match that with a 10kW input, and all will be well, however old and leaky the building. Full stop.

3. The other unavoidable fact is that a building with a higher heat loss will always cost more to heat than a building with a lower heat loss. If you live in an old attractive but leaky as hell cottage with a 12kW heat loss, as I do, it will always cost more to heat than a modern super-insulated house with a heat loss of 6kW, whatever the fuel. I will always burn more oil or gas, or consume more electricity, to heat my house than the owner of the modern well insulated house. Full stop.

4. Now we need to add the real world bit. By and large, most fossil fuel boilers are substantially oversized. In the past, it didn't matter, energy was relatively cheap, so just bang in a big one and be done with it. No need for all those tedious heat loss calcs, just guess it, multiply by two and fit a boiler that size. As a result, fossil fuel systems never get anywhere near being stretched beyond their capacity. They can almost always supply enough heat. Heat pumps on the other hand tend to be matched much more to the predicted heat loss, and that's where the problems start, because there is far less margin for error. Get the heat loss wrong, which as we know is very easy to do (my heat loss estimates from installers ranged from 9kW to 14kW, there is no way they are all correct), and if the error is to underestimate, and then match the heat pump to that underestimate, then the system will fail. A further pernicious problem is that heat pumps suppliers deliberately mislead about their heat pumps output. The headline output (in my case 14kW) is for a sunny day in spring, when I don't need 14kW. This very same heat pump however becomes progressively incapable as outside temps fall, and by the time it is zero degrees outside, it is only capable of putting out around 11.3kW. As my heat loss is 12.3kW, given a 14kW output branded heat pump, what could possibly go wrong. As you can see, quite a lot will go wrong once it get cold outside. The heat pump will never supply enough heat.

5. The other real world bit is failing to consider the whole heating system, rather than just the heat pump. Because heat pumps run at lower temps, they need bigger emitters to deliver the same amount of heat.  A cooler heat pump heated rad delivers less heat than a hot fossil fuel heated rad. Very roughly, the increase needed when moving from typical fossil fuel running temps to heat pump running temps is to double the size of the radiators. Even if you match a heat pump's output to the building's heat loss correctly, taking into account the lower performance at cold temperatures, if you keep your old fossil fuel rated rads, they will be too small, and the system will never deliver enough heat in cooler weather, and your house will be cold.

6. Lastly, heat pumps, because there is less margin for error, have to be commissioned correctly. Unlike a fossil fuel 'fit and fire' solution, heat pumps need to be tuned to match the building they are heating. This takes considerable time. Omit this step, as many installers do, and either the system will fail, or your fuel bills will go through the roof, because the heat pump has been left to run on it's most inefficient settings. It will produce plenty of heat, but with appalling inefficiency.

7. My own personal experience is in line with the under-performing heat pump in cold weather problem. The rads are all upgraded to match heat pump running temps, but in cold weather my heat pump fails to deliver enough heat, and my house fails to reach let alone stay at design temps. In warmer conditions, it is fine. The building is listed, reducing heat loss options are limited, and there is no way solar panels etc are going to be installed. I am 100% reliant on the heat pump replacing my old off electricity grid oil fired boiler.

8. The bottom line is there is no reason why within sensible limits a heat pump can't heat any building (as long as you have somewhere to put the unit, and a supply of mains electricity), you just have to do the calculations carefully and thoroughly, because there is far less margin for error. The sad fact is that the heat pump industry in this country has far too many jobbing workers who have done a half day course on how to fit heat pumps, which they then install with their old fossil fuel fit and fire mentality. Add in far too many have no idea how to do a valid heat loss calc (how on earth did my prospective installers come up with heat losses ranging from 9 to 14kW? They all had the same building to work with, and the sums are agnostic...). Result: failed systems. And this just happens more often on old leaky buildings because there is even less margin for error. It doesn't have to be this way, so long as you design, install and commission the system correctly.    

Postscript: I had a number of installers tell me they couldn't possibly fit a heat pump, my house didn't fit the requirements, far too old and leaky etc. They tended to have a sanctimonious air about them, but they were just as incompetent as the installers who got other things horribly wrong. To say you can't have a heat pump is just as wrong as fitting the wrong heat pump.           

I think you are correct. Unless you have a modern well insulated house, solar and batteries, the heat pump system is a huge gamble.

Perhaps I should have added that if personal income is such that heating costs don't impinge on other parts of living, then that is okay too.

@cathoderay 
Thank you for taking the time to supply such a long response. I will respond to the parts that I have an angle on one at a time. For the moment though I must provide the first response, which being anecdotal is, nevertheless, the situation that I am in it is not a myth.

"I have to suggest that, while anecdotally there may be accounts that suggest this is the case, in fact it is a myth."

The issue is not if the tech works but if it is affordable. I can only work from my own experience. Being comfortable in this leaky old house (LOH) with oil boiler cost £5-700 a year plus £600 electricity bill. So £1300 before the price increases which amount to doubling, means I should expect to spend £2600 and be equally warm. Even at £3000 a year I would okay and move on. But it is clear from my limited experience before switching the device off that it was not fit for purpose in this house. It cost £300 per month just to on/off heat less than half of the house. Now I know that the ludicrous concept of heating the whole house is part of the heat pump myth but there are two large rooms in my house that I have not even stepped into for two months. The idea that I should heat them anyway to act as a buffer against heat loss to the outside is the most flagrant inefficiency that is built into the heat pump concept. And of course, having a 16kw heat pump that is under used is inefficient in the other direction, recycling etc., either way it is wasteful. At least a carbon boiler does not sulk if it is not being used flat out but just gets on with supplying the demands put upon it.

"We need to separate fact from fiction here, and look at the real world and what happens in it. In practice, there is a bias towards old leaky building getting bad installations, but it doesn't have to be that way."

The problem is that it is that way. Not only were the fraudulent heat loss calculations created to justify the biggest heat pump they could get their hands on but they ignored the insulation and improvements that I was intending to do to improve the fabric of the house. The heat loss calcs supposedly reflected the building as it was not as it was going to be. When that work was done the installed pump was then going to be less and less efficient as the house became better insulated.

The ‘real world’ is that corporate installers look at the balance between highest return and least chance of being sued. The mess they make is someone else’s problem.

Posted by: @jswhite

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Perhaps I should have added that if personal income is such that heating costs don't impinge on other parts of living, then that is okay too.

This is a huge factor these days, and heating, of rather lack of it because of unaffordability, is a health problem too. But there is no getting round the fact that a building with a higher heat loss will always, assuming they are heated to the same design temps, cost more to heat than a building with a lower heat loss. This is where the mantra 'fabric first' comes from, ie always do all you can to improve the fabric of the building first, just as you intended to do. Sometimes options are limited, eg listed buildings. But they can still be heated with a heat pump, as long as you get the system design right, in most if not all cases. In extreme cases of unaffordability, it may even be necessary to think the unthinkable, moving to a home with a lower heat loss.

It is going to be 'interesting' to see how the various tariffs for different fuels play out in the coming months and years. At the moment, I am pretty sure I would be spending less on heating had I remained with oil, and if I had the option of mains gas, I am sure that would be less too. The problem is getting reliable data even just for current costs, let alone future costs, which can only ever be a forecast. Oftec have this chart (<=link), which is clearly nonsense: 

Assuming an ASHP has an efficiency of around 300%, then it must cost 1/3 less that standard mains electricity to achieve the same heating, but this chart suggests the difference is marginal. In fact, its bonkers. This table (<=link) appears to be reasonably competently put together, and is up to date, and suggests all the main fuel options are about the same cost per kWh, around 12p, with the exception of kerosene, the more usual 'oil' for oil central heating, which is a bit less, about 9p/kWh, and standard mains, which this table correctly shows costs about three times as much. I think they have slightly underestimated a standard ASHP system efficiency, at 270%, if we up it to 320% then the cost per kWh comes out at around 12p.

If cost alone was the only factor, we should all be running oil fired central heating, or rather bizarrely, be using LPG.                

Posted by: @jswhite

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Now I know that the ludicrous concept of heating the whole house is part of the heat pump myth

This isn't so much a myth as an absurd requirement imposed by MCS, who are the gateway to grants. They even tell you what temperatures your room must be at. I'm surprised they haven't invaded our bathrooms, and told us what temp the bath water must be, on pain of losing access to grants. The whole system is rigged because of this, installers can cook the books, just as you found out, and still appear to be MCS certified. There's nothing to stop them from putting in too big a heat pump, only a vague attempt to stop them putting in too small a heat pump, but even that doesn't work, as I found out.

It all comes back to information asymmetry. Currently, most householders interested in having an ASHP installed don't know enough, and the installers can run rings round them. This is why forums like this one are so valuable.   

Posted by: @jswhite

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The problem is that it is that way.

I agree, it could so easily have happened to me as well. The grant system had a preferred installer, and I assumed they had been chosen on merit. It was only after repeated incompetencies and failures I realised they weren't fit to install a 13 amp plug into a 13 amp socket, let alone design and install a ASHP based heating system, and got rid of them and replaced them with my preferred installer. The grant system preferred installer was the one who sent out the blind surveyor, and the final failure that got them fired was cancelling the installation on the Thursday before the Monday they were due to start because their proposed DHW would not fit in the airing cupboard, and they couldn't find one that would fit.

My core point is yes, I agree, the real world is like it is, but it doesn't have to be that way. I we consumers can inform ourselves better, then we can spot the cowboys, and tell them to stick their heat pumps somewhere where the sun don't shine. It will still leave Mrs Trellis of North Wales vulnerable, but overall, better informed consumers can only be an improvement.

I recall from reviewing older posts of yours that you have a Samsung heat pump. These are 'modbus accessible' via a two wire connection, and it may be  that you can tweak the pump to lower its output with the help of some input from Samsung experts (there are some that have discovered hidden ie not documented settings). Apparently a 16kW Midea unit can be cut back to a 12kW unit just by flicking a few dip switches, no modbus stuff needed to do that, other brands might have similar options hidden away. Most heat pumps can idle (without resorting to cycling) at around 20-30% of their max output, so if you can set your 16kW unit to be a 12kW unit, ~25% of that is 3kW, about the ball park you want. I know you have tried some of this before, but it can't do any harm to review things to see if there is anything you have missed.

The other thing is Homely, and Evergreen Energy. I think I am right in saying you ditched Homely because using it increased your costs, and that Evergreen Energy were 'the culprits' that landed you with a heat pump you neither needed nor wanted. Am I right in thinking your Evergreen Energy and Homely are now effectively one and the same thing? If that is correct and (I have to add this) your allegations are correct, then that rather casts a shadow on the whole Homely question. 

@Cathoderay,

Homely and Evergreen are one and the same.  From their website:

HOMELY ENERGY LTD

An Evergreen Energy Company

• VAT Registration: 322 0698 22
• Company Number: 11491139

@kev-m 
Also known as 'Deciduous Entropy'

@cathoderay it’s also the chaos of growth I think… a company may have 8 or 10 jobs on the go at any one week. That’s 10 plumbers of different attitude/hunger/passion and manners. A firm may have a very good ethos but who knows which plumber will be allocated to your job. Then - Why would a company invest in too much training and rounded knowledge only for their bright young star gets poached by Big Renewables Ltd…?

I think there’s a lot of ‘silence is best’ because nobody really knows the whole job and what’s missing. 

then the manufacturer runs out of key components but still supply things with missing chips on the quiet and hope that nobody notices. When something doesn’t quite work how it should who is to blame, who has been messing up the controls?

upfront honesty is the only answer!