Independent heat pump design advice

Talking to an old friend considering a heat pump installation to replace an oil boiler. I said that getting multiple quotes may not lead to the best solution as, typically, they are hard to compare.

I want to identify some experts who could come up with a requirement specification that could be quoted against. This would be a significant piece of paid work. However, in the long run it could be worth it. Location: South coast.

Any suggestions please?

Hi Paul,
we are MCS approved heat pump installers and ask people to fill in a a survey about house size and construction and use that to estimate heat load and therefore cost (excluding radiator upgrades) for the system i.e. it might cost £13k or £16k. We see quotes from other installers for systems smaller than we would have installed.
If people are serious about having a system installed we do a room by room heat load calc to check the radiators are adequete and calculate the size heat pump size required for heating (and hot water).
We charge about £200 for survey and design on system that we are installing.
We always apply for grid connection permission before starting the installation but that might be another thread…
Hope this help give an idea of what installers could / should do.

Thanks Paul,

The reason I was asking is that surveys from multiple installers tend to come up with different and conflicting proposals, presumably because they have manufacturer relationships to observe.

I found this confusing when I chose my installer and I don’t think I got the best result that way.

So I thought it would be better to have an independent assessment/ design against which one could get multiple quotes. Is this something you would be prepared to do? If not do you know qualified people who would?

Hi Paul,
Marion from the People Powered Retrofit Team here. We’ve been working on exactly this issue, trying to help clients understand all the numbers when it comes to heat pump sizing. Too often we find that heat pumps are over sized, which is both costly to run, and inefficient. We also advocate a fabric-first approach to retrofit meaning we prioritise improvements to the building fabric (insulation, airtightness etc) to reduce the heating demand first before switching to a heat pump. I could go into this further, but this hinges on a few things including how large a system can be run on single-phase domestic power, and electricity pricing being 4x that of gas.

Our current approach is to get a heat pump survey from an independent surveyor which looks at the fabric of the building, the current space and water heating demand, and the potential RHI grant in order to do a cost-benefit comparison based on capital expenditure, estimated running costs, and carbon emissions over the 7-year period RHI would be payable.

We’ve been lucky that we’ve found a heat pump installer who agrees with the survey findings and will use this information to size a system, however it is unlikely that this will always be the case as I understand MCS accreditation sits with the installer, with no separate designer accreditation, therefore the installer is liable for the sizing of the system (hence why they will do a survey themselves, usually for £200-300 which often comes off the install bill). We’re hoping this will change in the future, but this is the current system we’re working within.

In terms of capital cost for the system, this will change based on the manufacturer relationships (as you’ve noted), and any changes/upgrades to the radiators/pipework etc (as noted by @paul_chandler).

Where abouts on the south coast are we talking? We’re very much Greater Manchester-based, but we do have links to similar organisations around the country so might be able to point you towards someone in your area.

Hope this goes some way to answering your question?


PS @paul_chandler we’re looking to get to know heat pump installers in Greater Manchester - would be good to talk :slight_smile:


Thanks Marion,

Good to have your confirmation that my thoughts are on the right track.

If anything, 2 surveys would be a good thing. The extra cost could end up being a saving.

The people who ask me about this vary from week to week as I often mention that we took the plunge. I mentioned the South Coast as that’s kind of a locus of interest.

In the short term I’d like to find a consultant who I could refer interested parties to.

BTW. My installation does not include MMSP. I wish I had realised that I needed that. Now I’m having trouble finding anyone that offers this.


I’ve had a few people asking me (lol) about retrofit and heat pumps recently. One was someone asking on behalf of her parents in Salford so have directed them to Carbon Co-op/People Powered Retrofit.
My brother and partner live near Southend and are currently extending to the rear of their home. Their gas boiler is pretty old and starting to cost a bit in repairs so they are sensibly doing some research ahead of having to get it replaced in a hurry. Their house is not going to be anywhere near well insulated enough to go for a heat pump, but they are having underfloor heating in the new extension. So I want to advise them to think about becoming zero-carbon ready whenever they carry out any home improvements, including a new boiler. If they have a combi boiler, any thoughts about whether they should think about replacing it with a hot water tank system, even if it means making room for a tank? Is underfloor heating designed for use with gas boiler compatible with ASHP?
Is there a trusted independent organisation in Essex who can provide advice?


I have been recommended them by a few people. Otherwise try Octopus Energy. I suspect you may need to be an electricity customer.

Underfloor heating (UFH) has to be fairly low temperature, unless you want uncomfortable feet, and is therefore suitable for conversion to heat pump. Just make sure that there is as much insulation under the system as you can manage. The more insulation the more efficient the system.

Thanks Tim, the website looks interesting, but would like to have read a bit about the background of Jo and Caroline. For instance what are their qualifications to provide this kind of advice?

May be too late to influence the amount of insulation under the coils - the builders are on site, but will mention it. I’m aware that underfloor heating runs at lower temperatures, just curious about any potential incompatibilities.

I don’t know about their qualifications. They don’t provide the on site advice themselves but employ specialists. Having said that I don’t know their qualifications either.

I have relied on independent recommendations from different sources on the Octopus Energy Forum.

Fair enough - I’m always a bit suspicious of nice websites that fall a bit short on credentials… :grinning:

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We had our ASHP installed on 8th-9th April this year. So far we are getting an average COP of 3.25 overall; the combined value for space heating (effectively nothing since mid-late May), hot water and the standby consumption.
Breaking this down we are getting a COP of 3.68 during space heating and
a COP of 2.0 during the hot water cycle. Standby consumption is ~9W (really very low and probably lower than the elec our old boiler was probably consuming) which so far has represented 6% of the electricity consumed by our ASHP set-up.
The overall electricity consumed by the ASHP between 9th Apr to 9th Aug has been 382kWh, so the total running cost over that 1st 4months has been ~£70.
All these figures will change and consumption will go up significantly once the heating season starts again around late September (normally).