@oswiu, you’re doing the right thing. When we purchased our heat pump we didn’t have resources or communities to fall back on. As a result, we were sold a solution that I’d grade about 70%. Armed with the right information and questions we’d have a system that 95%. I hate to say it, but sales guys can’t be trusted and they’ll tell you anything to secure the sale.

Posted by: @grahamh

I wrote a book answering all these questions its on amazon, but why on earth would you buy a unit from someone who cant answer the qs? , getting idiots online to answer your questions is madness, you are giving these people a load of money, its probably a good idea you ask them. I wouldn't take dental advice from anyone but a dentist, i definitely wouldn't ask online mentalists for dental advice, heating is no different. 

Sadly, I think this speaks to the quality of installers in UK Graham. Quite honestly, I think the percentage of good/decent air source heat pump installers in under 20%. Maybe I’m being unfair because I’m mostly contacted by homeowners with dramas, but the biggest issue I’ve identified is lack of design and installations that are bodged as a result of this. Systems are simply slapped in to replace a boiler. That’s what happened to us, and scores of people on this forum.

Typically, the sales guys are nonchalant and they sell you a system based on their site visit and impressions. The installation team then arrive and install what you’ve been sold, which is purely based on the sales guy’s thoughts and they’re not qualified to make technical and necessary suggestions. They weren’t in our case and we had six companies come out to quote. They were all the same. So we have a system I’d grade at 70% which, when you spend over £16,000 you’d expect to be over 95%. Our system can’t even run weather compensation properly. It’s just not good enough. 

Posted by: @alec-morrow

Compensation controls are just glorified on off controls any way!

I guess this is true, but it depends how well the heatpump can modulate its compressor/flow rate. Most, it would appear to me, do not modulate all that much, perhaps down to 30-50% of their labelled power. I've seen that some Ecoforest models go down to like 15% which is really impressive and could theoretically mean no compressor cycling all the way from like mid autumn to spring if it was well sized and well controlled. 

I should start a thread for minimum power output because it has been interesting me lately. 

Posted by: @hughf

@oswiu have you thought about just designing the system yourself and paying a plumber to fit it? You've read the books, you seem perfectly technical, and you're going to control it with modbus anyway. If you want I'll ping you over the modbus registers for the Cool Energy 9kW unit and you can take a look at what you can control from in there.

I appreciate the vote of confidence! However, I don't think I dare go outside of MCS installations because it gives me recourse if something goes wrong, even if it doesn't seem to be all that effective reading stories here. Also, if I'm going to pay someone to install it rather than doing it myself (which I definitely couldn't do anyway), we really need that £5k grant to help with costs.

I would be interested to see the modbus registers if you have them to hand. I searched Github and couldn't see anything, so if you're controlling it like that, you might be one of very few! 

Posted by: @editor

@oswiu, you’re doing the right thing. When we purchased our heat pump we didn’t have resources or communities to fall back on. As a result, we were sold a solution that I’d grade about 70%. Armed with the right information and questions we’d have a system that 95%. I hate to say it, but sales guys can’t be trusted and they’ll tell you anything to secure the sale.

That's exactly it. I fear that in the ASHP world, if you don't know at least as much as the person selling you it (assuming they're a sales person), you're putting yourself at risk. I see no way out of this except with more bureaucracy which I'm sure installers would fight tooth and nail against. At least minimally informed consumers can look to Heat Geek verified installers for some kind of base standard.

@editor 

we had a quote from Global for our 4 replacement ASHP at work. They were Husky units before, so we’d already been caught out once. 

GES said their systems were the best if the best but we didn’t go with them as if they went bust we thought we’d struggle to get anyone to service them. 

Also we felt the innovation from Mitsubishi or Panasonic would be a lot faster given their number of installs. 

But I do know your pain. Their salesman was very pushy and persuasive unfortunately. 

Thankfully a lot can be done post install to improve efficiency. 

it’s just a shame my unit at home has 10m of preinsulated pipe that’s 28mm instead of 35mm!

Posted by: @editor

Posted by: @grahamh

I wrote a book answering all these questions its on amazon, but why on earth would you buy a unit from someone who cant answer the qs? , getting idiots online to answer your questions is madness, you are giving these people a load of money, its probably a good idea you ask them. I wouldn't take dental advice from anyone but a dentist, i definitely wouldn't ask online mentalists for dental advice, heating is no different. 

Sadly, I think this speaks to the quality of installers in UK Graham. Quite honestly, I think the percentage of good/decent air source heat pump installers in under 20%. Maybe I’m being unfair because I’m mostly contacted by homeowners with dramas, but the biggest issue I’ve identified is lack of design and installations that are bodged as a result of this. Systems are simply slapped in to replace a boiler. That’s what happened to us, and scores of people on this forum.

Typically, the sales guys are nonchalant and they sell you a system based on their site visit and impressions. The installation team then arrive and install what you’ve been sold, which is purely based on the sales guy’s thoughts and they’re not qualified to make technical and necessary suggestions. They weren’t in our case and we had six companies come out to quote. They were all the same. So we have a system I’d grade at 70% which, when you spend over £16,000 you’d expect to be over 95%. Our system can’t even run weather compensation properly. It’s just not good enough. 

 

Hi Mars,

I was giving this problem some thought last night.

There are various issues, one being the lack of knowledge required to produce a workable design, and a lack of trained personnel to implement that design, and also question it if it is wrong. Training costs money, so the company accountants will be inclined to suffer a heart attack should anyone mention the 'T' word.

MCS may set the standards and provide accreditation, but as far as I am aware no one is both enforcing the standards, or checking the quality and operational efficiency of the design and installation.

I worked for National Power on a new build power station in Pakistan, and one of my duties was to train and prove competent the maintenance teams under my control. Many of the local staff had never worked in a large power station before, so it was highly important that we ensured that they were adequately trained and fully competent before they were let loose on a running plant. The solution was to have each individual perform each particular task under supervision for three occasions, when they had completed all three tasks successfully to the required standard, they were than deemed competent to work unsupervised.

Something similar should be incorporated under the wing of MCS, where when a company sets up in business to install heat pumps and the like, they should have their first three installations observed and checked by a trained inspector. When they have completed three successful installations they would then be allowed to fly solo. To root out the 'cowboys', all installers would need to go through this process to gain accreditation and then be put on the accredited installers list.

The trained inspectors should also be used to investigate reports of poorly installed or operating systems, with the remit to call back the installer in question to rectify all the problems at the installers expense. This may then encouraged the company accountants that training is not a total waste of money and should be avoided like the plague.

and that explains why i have a job, i spend my days speaking to homeowners after they have had a site visit from thier installer of choice and have lots of qs, its a nice way to make a living, i do a zoom call for £64.48+ vat per hour and answer any qs consumers might have. 

Posted by: @grahamh

and that explains why i have a job, i spend my days speaking to homeowners after they have had a site visit from thier installer of choice and have lots of qs, its a nice way to make a living, i do a zoom call for £64.48+ vat per hour and answer any qs consumers might have. 

So that's where I'm going wrong, I do them for free. 😎

Posted by: @robl

@Oswiu

I assume your boiler is smarter than our old one, and has a display!  I’d encourage you to check it somehow versus the calibrated payment gas meter though still, just to be sure.  If you know the yearly gas useage in kWh, you can start with that.  Roughly, the peak daily load is 1% of the years gas use in the UK.  It’s down to the profile of heating degree days in your area, and it works for us, given you use hdd you could check that!  So if you used 10MWh of gas a year, assume 100kWh/day peak.  Then divide by 24 to give around 4kW peak load.  In practice you would want a heatpump more powerful than this, 5kW would just about do, 7 would be safer. 

For the radiator coupling - as above, turn all the heating on full.  When the rads have heated up, note the gas meter, start a stopwatch.  Wait exactly 15mins for good accuracy, note the meter again.  Multiply the difference between readings by 4 to give the kWh/h = power in kW.  Then you have everything you need!  Nb some meters need conversion from ft3 or m3 to kWh.

The results are in, and using a calorific value of 39.5 (my meter is in m3) and a flow temp of 70C, it started on about 18kW of gas usage, then settled on about 12kW after the return pipe had warmed up fully which took about 45 minutes. After efficiencies, this aligns quite well with the theoretical possible output power of my radiators (which I said was about 10kW), although I know that's based on the MWT, but I don't want to over complicate things.

I looked at the "heating demand" thing I mentioned and it just showed 100% for the whole time despite gas being used almost halving, so that's clearly not the best measure. I guess all I can say is that we've never needed anywhere near 10kW of heating as I know my heating has never come even close to being on 24 hours a day or even half of that.

So yeah, this hasn't been the best method to estimate peak load, but at least it feels like summer in my house again!

I am an installer, in London. I work on a bug variety if properties, but since 2006 when I started this work, I have always followed boiler manufacturers schematics, and used their controls. 

That has limited my offer, but I am left servicing my installs many over 12 yrs old (average u.k. boiler life 8yr, design life 15-20yrs.

So to any one buying into a heat pump I would ring the manufacturer, and ask for the installation book for you to familiarise your self with the work to be undertaken

In terms  of components these are what they will need to know

Heat generator type

Heating circuits; that could be all radiators usually one zone or radiators and UFH usually two zones, but you could have up to 8 zones.

and hot water cylinder.

You are buying in to a new(for the U.K.) paradigm, it shouldn’t be an adventure as the technology is proven in other countries and mature.. but hey ho…this is the UK

@Oswiu

I think that assuming your internal temperature is 22C (you said it was hot) then I think the radiators couple as:

(Temp_flow - Temp_air) / Power = (70C-22C) / 11.5kW = 4.2degC/kW.

Now we just need your expected heat demand, and you can estimate the required maximum flow temperature, assuming nothing changes*.  Some time back you suggested 6kW - if that's still your best estimate**, and we assume that the heatpump spends 24 hours a day heating the house, then the maximum required flow temperature to maintain 20C indoors would be as below.  

Tflow = 4.2C/kW * 6kW + 20C = 45C

I think that this is fine for most heatpumps to do.  With weather compensation, it will often be below this.  Lower is still better, there's always a COP v flow temp tradeoff.

Nb: disclaimer disclaimer...I'm a diy-er!  The above calcs worked fine for me for our house - predicted Tradiator = actual Tradiator = 32C, which as Graham H says, it is hard to tell if it is on, but I don't care about that :-).

*It's likely increasing the pump speed would reduce peak flow required, by dropping the DT (Tflow-Treturn).  What was the return temp, so you can judge if it's worthwhile trying?

**better could be found either from a max daily gas use, or failing that a years gas use, and I'm also assuming that that you maintained an average 20C internally on the coldest day.