Getting a heat pump - Checklist
Enhance your knowledge by reading our Demystifying Heat Pumps explainer. Also visit Energy Saving Trust energysavingtrust.org.uk, and more in-depth sources like Heat Geek www.heatgeek.com and BetaTalk - The Renewable Energy and Low Carbon Heating Podcast - Ignore anyone who repeats discredited myths (like “you can’t heat an old building without ‘deep retrofit’” - i.e. massive amounts of insulation).
Use Nesta’s ‘Visit A Heat Pump’ scheme www.visitaheatpump.com and/ or visit a trusted friend/ neighbour to learn things from owner-occupiers who have one.
Get at least two quotes and cast your net wide, and always request and follow up on references. Trust your instincts regarding provider professionalism/ viability (see How To Select A Heat Pump Installer below)
Ensure provider is thorough in relation to assessment / survey, as follows:
Proper survey of existing pipework, radiators & location for hot water tank;
Room by room heat loss estimates; and
Radiator sizing (or other emitter) and proposed changes (often, surprisingly few need to be upgraded, so if complete change proposed, challenge why).
Mains water pressure check;
Electricity mains supply/ fuse check (an independent electrician’s load survey advised - often current fuse is sufficient but it needs to be checked);
Current planning rules; etc
Remember you need an cost effective approach not only an efficient system, to keep costs and disruption down (e.g. minimising radiator replacements)
Ensure written proposal includes
Use of ‘weather compensation’ to reduce flow temperature as far as possible consistent for installation budget (and certainly not use a fixed flow temperature):
Predicted SCOP (Seasonal Coefficient Of Performance);
Predicted electricity usage;
Estimated carbon savings;
Installation costs (incl. parts and labour), and costs of support / servicing;
If quotes are significantly different (e.g. on 5.2 and 5.3) , explore why.
Also judge installer on how well they listen and communicate.
Ensure you’ll have the ability to monitor COP (Coefficient Of Performance) via console or App, and determine the SCOP, which should be at least 3.5.
Avoid hybrid solutions (e.g. gas ‘back up’, for which there is no good reason)
Be wary of ‘high temperature’ heat pump offers (needs a strong case).
If large supplier / new entrant, be wary of sub-contracting, especially to inexperienced people (may lead to finger pointing & difficulty resolving issues).
Be sure to assess overall offer (post-installation fixes; support; servicing; etc) and credibility (companies cannot rest on past laurels and need to continually prove themselves in delivering quality installs with good outcomes).
How To Select A Heat Pump Installer - Guidance
There is no easy flow-chart to find the right installer for you and NailsworthCAN is a community group, independent of any political party, company or any other affiliation. We therefore do not recommend named suppliers for heat pump installations.
However, we do offer guidance here on how to go about finding an installer.
The good news is, there are many householders out there with great experiences and very successful installations, and if you can learn from them, you will be well on your way. The following guidance is really aimed at helping you to take a thoughtful and measured approach.
How do I find potential installers?
Prospective installers will usually be registered with one or more of relevant industry bodies such as MCS, NAPIT and TrustMark. This is reassuring and provides some protections, but unfortunately, does not on its own guarantee a great outcome. You still need to check a potential supplier out.
You can use the MCS (Microgeneration Certification Scheme) ‘Find an Installer’ tool https://mcscertified.com/find-an-installer/ to find potential names for installers. We would recommend casting your net wide, but not so wide that it is difficult to get the supplier to come back at short notice to fix snags post installation. A 50 mile radius might be a good compromise.
There is a community of heat pump engineers called Heat Geek https://www.heatgeek.com (their engineers can be sole traders or work as part of, typically, a small or medium sized company). They provide training of engineers, and monitoring and backup of installations. It is worth exploring this option, but all the questions we raise for MCS registered suppliers apply equally here.
Finally, add to your prospective list of suppliers any that you have heard about from friends, neighbours and trusted experts in the community who have had good experiences.
You might end up with a list of 10 prospective suppliers by now and need to reduce this to 2 or 3 who you will ask to quote for the system.
How to assess the quality of an installer
Whatever service you procure in life, it is always crucial to trust your gut and be able to answer the question honestly ‘do I trust this supplier?’. In a fast changing market there will be a range of suppliers both big and small, new and old. Ensuring you get experienced people arriving on site is key, but so to is understanding their approach and the overall customer experience they provide.
You should also ask a supplier to explain their overall approach to design, delivery and support. If you feel ‘talked down to’ then that is not a great sign. You want to feel that you are talking to experienced professionals who are confident in consulting with you in a respectful way, and take into account your needs in the design of the system.
Also, successful projects rest on good communications. A supplier needs to demonstrate that they can both listen and respond promptly, even if it’s a “we’re working on an answer”.
Beware of the risks of a system that is over sized
Installers use estimates of key parameters in their models (like the heat loss through your walls, ‘air changes per hour’, and much more) to assess your home’s energy demand. If they are too conservative in these estimates they can compound and lead to an oversized system. The net result can be a bigger heat pump than needed and more radiator upgrades than is strictly needed. You may be comfortable with that, but if your budget is tight, you really don’t want any significant over-sizing. While there can be situations where significant changes are needed (e.g. very poor exisitng plumbing and ancient radiators), it is worth checking that while the system proposed is well sized it is not oversized.
On the other hand, do remember that you have to think about the longer term. So if you are a retired couple in a large house and you are getting a heat pump, it might be better to design the system for the house not for your current more modest needs! It will then be capable of supporting a family in the future if you decide to downsize (e.g. having a hot water tank that will be suitable for 3 teenage children!).
This would also secure the value of the home when it is sold (Savills have noted the higher sales prices for homes with green tech). In any case, have the conversation with the supplier to explore options.
There is a question mark over what performance you wish to achieve that is consistent with your goals which may be quite varied (e.g. level of disruption, installation costs, running costs, carbon savings). The highest performing design migh require more radiator upgrades, increasing the installation costs but reducing the running costs. So there will be a trade-off.
People will say the minimum efficiency you need to achieve is a SCOP of 3.4 to compete with a new gas boiler (at current, Oct 25, gas and electricity unit rates) , but if you are happy simply to break even compared to your old gas boiler that has an efficiency of 75% or worse, then a SCOP of around 2.9 is enough to do that (see Note on Bills Savings and Break-even Performance at end of this page).
Relevant to this section, Heat Geek are now offering a ‘ZeroDisrupt’ service (for dwellings below a certain level of complexity and heat loss) with the goal of minimising disruption and cost, while still delivering good performance. See Adam Chapman describing it here. If you don’t like the idea of using a sole trader, it might be worth finding a supplier that has a Heat Geek trained engineer on its staff, and ticks all your other boxes in terms of customer service, etc.
NailsworthCAN is not recommending ZeroDisrupt any more than any other option, but we do think it is worth considering. Some suppliers may say they already ensure they do not oversize systems, so keep an open mind, and in any case, for more complex cases (large houses with complexities), a bespoke solution will be needed, irrespective of who is delivering it.
Boiler Upgrade Scheme
There is a current ‘Boiler Upgrade Scheme’ (BUS) with a grant of up to £7,500 for an Air Source Heat Pump ‘air to water’ system (which this guide mainly focuses on). You need to check if you are eligible https://www.gov.uk/apply-boiler-upgrade-scheme/what-you-can-get . This gets paid to the supplier and should then reduce the cost of the installation for the consumer.
The BUS now includes ‘air to air’ systems with the lower grant of £2,500, and for which there are a number of restrictions (it must be the main source of heating etc.). More background on air-to-air system and other options by Energy Saving Trust can be found here https://energysavingtrust.org.uk/advice/air-to-air-heat-pumps/ . An air-to-air system must be capable of providing all the heating demand for the house (hybrid solutions not eligibles for the grant). Air-to-air systems that are only used for cooling (i.e. “Air Conditioners”) are also not eligible.
The House Survey
Often suppliers will offer a free ‘desktop’ estimate that simply makes a judgement based on the age and style of house, just to test if you are a ‘serious’ buyer, but this shouldn’t be sufficient for signing an agreement.
A room by room, on site assessment is essential to get a good estimate of system requirements. Suppliers will usually charge for this, but then many will offer to refund the money if you go with them.
Arriving at a Shortlist of Suppliers
To reduce the prospective list of 10 down to 2 or 3 we suggest you use questions that explore a supplier’s current experience, for example (not intended to be exhaustive):
How long have you been in business as installers of air-source heat pumps?
How many installations have you done in the last 3 years?
How do you ensure your in-house staff have the necessary skills?
Do you ever sub-contract your installations and why? [be very wary of any sub-contracting as it may be a sign - particularly with larger companies - of trying to enter the market without the necessary skills in-house]
Can you identify 3 homes similar to ours, with owners who are open to an on-site visit to discuss their experience, where you have been responsible for the design, installation and support of the system?
Will you provide a substantive quote showing room by room heat loss estimates, estimated SCOP (Seasonal Coefficient Of Performance) and estimated electricity usage, to meet agreed heating goals?
How do you ensure the approach is as cost effective as possible without compromising performance?
Do you always use ‘weather compensation’ in setting up the system?
Can you outline your end-to-end delivery process from planning to completion of the project?
Based on how comfortable you are with the answers to these questions, you can create a shortlist, and then move to requesting a proper survey and quote (which must involve a visit to the house, lasting a few hours typically). Don’t think of the cost of a survey as an overhead, but as a way to potentially save money to ensure you get the right supplier (for you), the right system, and to avoid issues later.
Review the quotations
The quote should include the items listed in the Checklist above.
It also needs a clear staged payment schedule, and start and end dates. You also need to understand if call outs after installation to remedy snags is included in the quoted costs.
You need to know what the annual service charge will be (typically, no more than the cost of servicing a boiler).
Once you have the 2 or 3 quotes, spend time assessing them, and compare them. Don’t be rushed or pressured.
If the quotes differ a lot in basics (such as the heat loss) that will raise questions about their methods. They may also differ due to different sizings of system components (less experienced installers may ‘play safe’ by oversizing some or all componemts), based on different assumptions or levels of experience.
You may wish to find someone you trust with experience to help review the quotes. Go back to the supplier with questions if needed.
Proceeding with a supplier
Once you have selected and signed up to a supplier, what happens next?
The process of the installation itself involves several steps (see example below).
The approach to after care is also key. There may be good reasons a snag occurs (e.g. air lock in some piping) but you shouldn’t have to pay for that.
If, as noted in the checklist above, you are able to monitor the actual performance of the system (using an App or via a console in the house), you can see if it is working as efficiently as expected (see below). If not, the supplier needs to address this. Some suppliers are now providing proactive monitoring of installations, and can spot if issues are arising which sometimes are due to householder behaviour (like leaving French doors wide open on a cold day!) but may be due to a system snag (like the radiators not having been ‘balanced’ properly). Either way, you need good customer service to respond to concerns.
Once you have an up and running heat pump that is properly set up and running as promised, the best advice is to let it do its thing - no fiddling with controls, or radiators, or anything else.
Monitoring performance
It is worth checking on the performance (Coefficient Of Performance) during the first week, then the second, then the first month and some more, till you are comfortable that the system performance is as promised.
If during a week’s period there is a dramatic drop in performance, then that may require a service call to remedy a snag (e.g. an air lock in the pipe work that can cause the heat pump to stop is possible while the system is settling in).
On an annual basis you need to determine what the SCOP is (the Seasonal COP), which is equal to the heat delivered to the house divided by the electricity used by the heat pump (e.g. 32,000 kWh / 8,000 kWh equals a SCOP of 4).
If the SCOP is not similar to the projected number in the quote (e.g. if the quote promised 3.8 and you are getting 3.2), and you are confident there have been no adverse ‘behavioural changes’ (e.g. more windows being left open) you should contact your supplier.
However, generally, once it’s set up, a heat pump is reliable and keeps going year in year out, but as with your old heating system, we recommend you have an annual service of the your heat pump.
Installation Steps - An example
Let’s imagine you have signed the agreement with your preferred supplier, and you have a date for the start of installation. So what happens next?
In the essay Heating a listed Cotswold stone building with an air-source heat pump: our journey it provides an example of the steps followed in that case (which didn’t require any pipework changes and only a third of the radiators up-sized from double to triple panel ones, despite it being a 200 year old, listed building):
Introduction to installation team, and logistics agreed (like parking and house access)
Old gas boiler and tank removed
Existing pipes and radiators flushed
Heat pump and other kit moved into position [a pre-prepared reinforced flat area was created for siting the external kit]
Plumbing in of kit (heat pump, hot water tank, etc.)
Plumbing in the few new radiators required
Heat pump connected to electrical power
Control system installed
One wireless thermostat placed in living room, set to 21°C [keep it simple]
But, setback thermostat by 3°C to 18°C between 10pm and 6am
Various control setups competed
Weather compensation setup
System put into operation
Radiators ‘balanced’ to ensure optimal heat distribution [and after this, radiator controls eg. TRVs (Thermostatic Radiator Valves) never touched again!]
Metering to monitor performance installed [in this installation, using 3rd party meters for flow/return heat and electricity usage, but often people use the in-built metering provided with heat pumps]
Certificates produced for MCS compliance
Hopefully that gives you some feeling for what might be involved in your case.
Note on Bills Savings and Break-even Performance
We need an answer the question “will I pay more to heat my house with my new Air Source Heat Pump than I did with the old gas boiler I’m retiring?”
Too often people ask a different and less relevant question, which is ‘what is the breakeven cost for a new heat pump compared to a new gas boiler’, where the ‘new’ is often not stated but implicit. Why ask this question when the vast majority of householders looking to get a heat pump will have an ageing gas boiler?
Also, the ratio of electricity unit price to gas unit price (the so-called ‘spark gap’) in the UK, which is one of the highest in Europe, will often be raised as an issue, and it is, but we argue not sufficient to stop anyone acquiring a heat pump.
Let’s consider an example to find out.
Take a house that currently uses 30,000 kWh of gas for heating
Gas unit price of 6p/kWh => £1,800 per year (ignoring standing charges for the moment)
With an old gas boiler that is 75% efficient (this can be optimistic in many cases)
So, building needs 22,500 kWh of heat reaching radiators
So the question is, can a heat pump be cheaper to run with its high relative performance that counteracts the ‘spark gap’? Let’ see ...
Let’s take a Heat pump system that has a SCOP = 3.5 (should be easily achieved by an experienced installer)
So heat pump needs 6,429 kWh of electricity to produce 22,500 kWh of heat (22,500 / 3.5)
With an electricity unit price of 22p/kWh that means £1,414 per year to heat with the heat pump
That is a saving of £386 on running costs
There is a slight health warning here, because this difference is very sensitive to the ‘spark gap’ (ratio of electricity to gas unit prices), and crucially the SCOP. achiieved.
Although it is worth noting that in the future, with more renewables, an enhanced grid and a reformed electricity market, heat pumps will become cheaper to run much more easily, as renewables electricity will be significantly cheaper than electricity generation from gas turbines.
In the meantime, there is still much that can be done to reduce installation and running costs.
If we include standing charges and using the same rates as above, the breakeven SCOP is about 2.9, which is easily achieved and surpassed by any competent heat pump installer.
Bills including Standing Orders as SCOP is varied
Parameters: With heat demand of 22,500 kWh and old gas boiler with efficiency of 0.75 (75%), so gas bill showing 30,000 kWh primary energy used by gas boiler. Used standing charges of 28p and 59p per day for gas and electricity, and unit rates of 6p/kWh and 22p/kWh, respectively. The breakeven running costs SCOP in this case is 2.935. Also, a carbon intensity of gas of 184 gCO2/kWh and for UK electricity grid (for 2024) of 124 gCO2/kWh; so even at a SCOP of 2.5 you save 4.37 tonnes of CO2 a year.
With a realistic minimum SCOP of 3.5, the savings on the bills are £272 in this case, with Standing Charges included, less than the rough calculation we did earlier, but still a saving.
What this also shows even with a pessimistic SCOP of 2.5, huge savings in the domestic carbon footprint are possible.