@editor your opening statement on the thread states that "heat pump installers and association members that have taken exception to me stating that less than 20% of heat pump installations in the UK have been flawlessly designed and installed, bringing the competency of installers into question.

This is unsurprising given the high bar that you are setting almost to ensure your 20% statement is validated.

@gmuzz, no, I’m not setting an artificially high bar to validate anything. I’m setting the bar where it should be when you blow £10k–£20 on a heat pump: accurate heat loss calculation, correct unit sizing, appropriate emitter upgrades, sound hydraulic design and proper commissioning so the system delivers expected comfort and efficiency as it should.

That isn't perfectionism... that is baseline professional competence IMO.

If fewer than 20% of installs meet that standard, that’s not because the bar is unfairly high it’s because execution is wildly inconsistent.

When you retrofit a heat pump into an existing property without rigorous heat loss, without emitter verification, without system design thinking and without careful commissioning, you’re rolling the dice. And way too many homeowners are discovering that after the fact.

If the data shows I’m wrong and 60-70% of systems are technically sound first time, I’ll say so publicly. No problem.

But I’m not going to redefine good downward just to make everyone more comfortable.

When people invest that level of money into heating their homes for the next 15+ years, I think they're entitled to expect proper design, proper sizing, proper commissioning, etc.

That’s not an extreme bar. That should be par for the course. 

@toodles, you’re not wrong... perceptions will vary depending on knowledge, experience and even physical access to the system. Someone who’s never dug into heat loss calculations or emitter sizing may only judge the system by noise and comfort, and that’s fine... it still reflects part of the homeowner experience.

That said, this poll and forum topic are deliberately weighted toward the basics that I think matter most: design, sizing, commissioning and whether the system delivers the comfort and efficiency it should. Those are things every homeowner can judge, even if they’re not a technical expert. For example, did the house heat up, is it insanely expensive to run, did the installer explain the controls and were there avoidable issues requiring revisits.

@editor, Mars, I really appreciate the update to the wording of Poll options one and two. My issue was never a fundamental objection to the word flawless, it was that the supporting comment doubled down with “perfect in every sense”.

The change to the supporting comment now guides the Poll user in exactly the right direction from my point of view and still keeps the distinction from option 2, thanks.

Thanks @woofers64. It was a fair point, and the distinction between 'flawless' and the next tier needed to be clear, without implying unattainable perfection, and it’s good to know the updated wording strikes that balance.

Posted by: @editor

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Thanks @woofers64. It was a fair point, and the distinction between 'flawless' and the next tier needed to be clear, without implying unattainable perfection, and it’s good to know the updated wording strikes that balance.

I had avoided answering the poll for this reason, as there was something of a seismic jump between flawless perfection and an installer having to revisit at least once, neither of which were appropriate responses for my system.  The new wording is better in this regard and allows the first option to now be 'close enough' for me. 

I think the description of the 2nd option as "very pleased, system fundamentally sound" would be my preferred choice, but the implication of 1-2 follow up visits within it rules it out.  Ideally, there needed to be something between the two that was just restricted to this comment.

My boiler had its service back in July last year (2025) and wasn't aware until September that the heat exchanger had failed and wasn't covered under the current insurance plan, I was told it had a blockage due to a so called dirty system which I knew was not true as I had completed a full drain down of the system a few years earlier with a flush of each rad clean of the header tanks and along with a twice yearly magclean check and it was coming out clean.

I had already been doing loads of research into ASHP and the pros and cons, I was already in a good position with Solar although 13 years old and generating about 2kwh and a 2 year old Tesla Powerwall 2.

With the research that I had been doing (watching lots of YouTube video's) I had already decided I was going to use HeatGeeks to do my install as I couldn't guarantee a local installer with enough knowledge to complete the job, and HeetGeeks could Guarantee a minimum efficiency. 

I did contact other well known installers on Heatpumpmonitor but I was out of the area they support.

I had already been playing with HeatPunk so knew the sizing and rads and had been playing with flows etc in the application.

I did look at replacing the Gas Boiler with another, which was going to come out at £5000 minimum and 90% efficiency, our boiler was only being used for heating so only on for about 4 to 5 months of the year so seemed to be crazy to go that route, the hot water was being done via the battery and the emersion.

With a heat loss survey via Jamie from HeatPumpSpecialists via HeatGeeks which actually took almost a whole day to undertake which is from my research about right, with a proper detailed look at each room.

Jamie and I clicked, I am in I.T and have a Geek for all things data and with Jamie's passion for ASHP I knew he was the guy for me, I already had questions up my sleeve to ask that only a true ASHP installer would be able to understand and answer, a lot of the questions actually came from the renewable hub podcasts, but Jamie could answer them with ease.

With the quote for the ASHP which for a lot would be off putting, I put all the data into a nice spreadsheet with calculations on worst case scenarios and best case and worked out the calculations.

There are a few video's on youtube about how to calculate this.

I was already on a very good time of use tariff, and could easily manage the load balancing of the house, the Tesla battery already covered the house load for the day with spare, but the question was how much extra would be required with the ASHP, this is a question that no one can answer as its all individual, how hot is the house kept at, how often do you heat the hot water, what flow temperature do you run it at.

I was aiming for the best efficiency possible but keeping the house warm.

With all my calculations even with the ASHP going to cost a lot more than a replacement boiler, I still calculated that my return would be substantially shorter than a boiler, I know a lot of people don't believe this is possible.

Coming into November with still no heating which didn't bother us at the time as the house was still relatively warm Jamie adjusted his work schedule to fit our ASHP.

Jamie at HeatPumpSpecialists was very particular with his install having already had the base installed the week previous ready for the massive 12KW Valliant.

The attention to detail in the new plant room is really well done but only let down by me not painting it beforehand and slightly by the electrician as his regular was unable to attend I would have prefered the electrical cables to be done slightly differently but it doesn't affect the working.

The install took slightly longer than expected with a few obstacles along the way well we did have to replace all the radiators and deal with all the old pipe work in the now old airing cupboard.

One thing that was mentioned was how clean the heating system was when it was taken apart, no sign of sludge in the rads etc.

Jamie configured the basics to the best optimal configuration and left me play and dial in the final heat curve and temperature, as mentioned above I already had an understanding of configuration etc. again loads of information available.

Since its been installed, we have got the following efficiency readings.

November 5.17%

December 4.89%

January 4.79%

February 4.93%

My wife is super happy and is now promoting ASHP and has said several times that she only knows that is running when she walks in front of the fans.

It just goes to show that with the right installer who knows what they are doing ASHP will work. Our install is saving us over £100 a month through the winter for everything as of course we now have to take from the peak rate near the end of the day 🙁 but we are leaning and monitoring what our usage is.

My calculations that works out as £39.70 to run the heating and hot water for all of December which is going against my December 2024 gas bill is a saving of over 70%.

So I would highly recommend Jamie at HeatPumpSpecialists.

Thanks 

Sorry for the long post.

@n1ckw Just a thought, if you are taking in from the grid at peak rate but you have a Powerwall, may I enquire which tariff you might be using please? We have 27 kWh of PW2’s, 8 kW Daikin heat pump, induction hob, Sunamp Thermino ePC210 heat battery and are a fully electric household. (Gas was stripped out a few years back). We are on Octopus Cosy and the 3, 3 and 2 hours spread through the 24 hours enables us to avoid the peak rate from the grid altogether; in fact, normally we only ever use the cheapest periods and rely on battery and solar (8.1 kWp. with less than ideal orientation and some shadowing) for the other 16 hours each day. We do export some power and will probably return to Intelligent Octopus Flux tariff when the Spring is well under way. Regards, Toodles.

@editor you've put out some brilliant vids on YouTube recently. Keep up the good work. 

Logging back on here I see that my posts from 2022 (when the install went in) were all very positive. Hooray. However, now that we've lived with the system for a few years I think we are a bit more 'hmmm' about the install. It's not terrible, but I think it could have been better. At the time I guess it would be rated as good(ish), but judged against good installations that you now see online I think there are lots of design features that would be questioned - possibly due to rushed decisions made by the installation team during a very cold winter install in Jan 22. In terms of your points in an earlier post:

• accurate heat loss calculation - not really, or at least I think it could have been more rigorous 
• correct unit sizing - yes, but then it changed on the day of install and we were 'upgraded' to a larger unit for free. It works OK. But I wonder whether we should have pushed back for the unit initially suggested? 
• appropriate emitter upgrades - pretty good on this apart from one in the kitchen that should have been changed. We have now installed a second emitter on the opposite side of the kitchen which has made a huge difference this winter.
• sound hydraulic design - how would I know???? I think it's OK...
• proper commissioning so the system delivers expected comfort and efficiency as it should - sort of. It was quick and then follow ups were done over video calls, but it wasn't until this winter when I've had the confidence to start poking around the system that I've been convinced that it could keep the house warm for a reasonable cost.

The unit is noisy when the outside temperatures get down below 5C and the costs seem high when temperatures drop below about 3C. A software update from Daikin massively improved the electric consumption of the unit during cold weather - excellent young engineer who came and looked into that and wouldn't leave until he had it diagnosed and sorted out. Oh, and as seems to be the way in the fledgling renewables sector - our installer is no longer trading. Yay. 

I'd probably go back to gas if it was an option, but we've made the choice and I'm sure over the next few winter seasons we'll keep tweaking things. Hopefully they'll be reasonably mild, because it works best in those conditions.    

Posted by: @justme

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proper commissioning so the system delivers expected comfort and efficiency as it should - sort of. It was quick and then follow ups were done over video calls, but it wasn't until this winter when I've had the confidence to start poking around the system that I've been convinced that it could keep the house warm for a reasonable cost.

Posted by: @justme

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I'd probably go back to gas if it was an option

Just to comment on this, if you get the adjustment right, your house should be more comfortable, possibly much more comfortable, with a heat pump than it was with your gas boiler, unless you were running your gas boiler with low flow temperature and weather compensation.  The latter is very possible but also rare in the UK, and furthermore needs exactly the same tweaking as with a heat pump - ie the tweaking is more a feature of low temperature, weather compensated, heating than it is a feature of the heat source itself.

It sounds like you may not yet be at that point.  

@jamespa Thanks for that point. In our previous house we had a weather compensated gas boiler that was really well installed and the installer went through everything during set up. And after that it just worked really well. Then we moved, the gas boiler failed in the first winter and we decided on the heat pump. We don't have the funds to go back to gas (and if I'm really, really honest, I think that would feel like the wrong thing to do). Like I say, the heat pump based system is OK, but it's just seems a lot of faff to have running well.

Posted by: @justme

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Thanks for that point. In our previous house we had a weather compensated gas boiler that was really well installed and the installer went through everything during set up.

Thats sadly very unusual in the UK so far as I can tell; you were very lucky. 

Most boilers (again so far as I can tell) are slapped in, flow temp turned up to max, TRVs on all rads, installer walks away.  Homeowner is warmish but temperature gradients are much higher both in time and space than is necessary and running costs 10% or more higher than they should be because boiler is cycling frantically because its way oversized, and not condensing.  Basically warm, but not comfortable or efficient.  However as homeowner knows no better, installer doesn't get a call out so is happy.  If the homeowner does have the nous to turn down the flow temperature, it gets reset to max the next time its serviced. 

Its must surely in part be because of this learned behaviour that setting up heat pumps isn't always done well,

What you needed was the installer who did your gas boiler to set up your heat pump, its the same process after all, unless you do silly things like over-zoning or adding in unnecessary buffer tanks which, sadly, many heat pump installers still do for reasons that defy reasonable explanation.

The other difference is that boilers with weather compensation are generally European, whereas heat pumps are frequently far eastern.  The European manufacturers, because they were forced to do it for boilers (it is mandatory in some enlightened EU countries), have sometimes developed a better, albeit still not perfect, interface to WC than the far eastern manufacturers.