Why this decision matters more than the equipment
People agonise over which brand of heat pump to buy and then pick the installer on price. That is the wrong way round. A mid-range unit designed and commissioned properly will outperform a premium unit fitted badly, and the difference shows up in your bills every month for the next fifteen years.
The reason is the efficiency figure. As set out in our guide to whether a heat pump is worth it, a system needs a real-world seasonal efficiency of about 2.8 to beat a gas boiler on running cost. Whether yours lands at 2.5 or 3.6 is determined almost entirely by design decisions: how the heat loss was calculated, what flow temperature the system runs at, whether the radiators were sized to match. All of that is the installer’s work, not the manufacturer’s.
This page covers how to verify an installer, what changed in 2026, what a good survey and quote look like, and what to do if it goes wrong.
MCS certification is non-negotiable
The Microgeneration Certification Scheme is the quality certification behind every grant-eligible installation in the UK. Without an MCS-certified installer there is no Boiler Upgrade Scheme grant, no exceptions, and since October 2025 MCS has been the sole certification scheme recognised for clean heat measures under government-funded schemes.
Certification is held by the business, not the individual engineer. It covers technical competence, but also the unglamorous things that determine whether a company is still around in three years: record keeping, complaint handling, financial stability.
Verify it yourself rather than taking their word for it. MCS runs a public installer search on its own website where you can look up a company by name, postcode or certificate number. An installer who is genuinely certified will give you their MCS number without hesitation. One who deflects, or who says they work “under” someone else’s certification, is a problem: subcontracting arrangements of that kind are a common way for uncertified firms to appear legitimate, and it puts your grant at risk.
What changed in 2026, and why old advice is now out of date
Almost every guide to choosing a heat pump installer tells you to check they belong to a consumer code, either RECC or HIES. Until recently that was correct, because MCS required it. It is no longer the whole picture, and the change is recent enough that a lot of published advice has not caught up.
MCS has been rolling out a redeveloped installer scheme, its biggest overhaul in two decades. Core documents were published in January 2025 and installers are transitioning in phases, with certification bodies moving businesses across through 2026. All certified installers are expected to have transitioned by 31 March 2027.
Under the redeveloped scheme:
- Consumer code membership is no longer mandatory. DESNZ has formally recognised the redeveloped scheme as a Code of Practice for the Boiler Upgrade Scheme, which means installers certified to it can deliver BUS work without belonging to RECC or HIES.
- Financial protection is mandatory instead. Every domestic installation must come with an MCS-approved financial protection product, reported as lasting at least six years and covering you if the installer goes bankrupt, retires, refuses remedial work, or if there is a design failure.
- Complaints are handled centrally by MCS, with a regulated alternative dispute resolution route, rather than bouncing between the certification body and a separate consumer code.
- Assessment is risk-based, with more scrutiny of actual installations and less of back-office paperwork.
- A named Technical Supervisor is accountable for every job.
What this means for you as a homeowner is simple but easy to get wrong. During the transition, installers are on one scheme or the other, so there is no single right answer to “which protections do you have?” The useful question is:
“Have you transitioned to the redeveloped MCS scheme, and what financial protection comes with my installation?”
If they are still on the old scheme, they should hold RECC or HIES membership and provide an insurance-backed guarantee. If they have transitioned, they should provide an MCS-approved financial protection product, and consumer code membership is optional. Either answer is fine. No answer at all, or visible confusion about the question, tells you something about how closely they follow their own industry.
Where to find installers
Start with the MCS installer search, which is the definitive list of certified businesses and lets you filter by location and technology. Three quotes is the right number: one gives you nothing to compare, and beyond three you are mostly adding delay.
Two practical notes. In rural areas, particularly for the off-grid properties where the £9,000 grant applies, MCS-certified installers are thinner on the ground and lead times are longer. Build that into your timing. And be wary of lead-generation sites that take your details and sell them on to whoever has paid for the postcode, which is not the same thing as a curated list.
We don’t take payment from installers. That’s why we’ll always tell you to verify certification independently on the MCS search rather than relying on anyone’s directory.
The survey is where you learn most
A proper survey takes a couple of hours and involves someone going into every room with a tape measure and a laser. What they are producing is a room-by-room heat loss calculation, which determines the size of the heat pump, the flow temperature and which radiators need changing.
Anything less is guesswork, and guesswork produces oversized systems. Oversizing is the single most common failure in UK heat pump installations. An oversized unit short-cycles, running in bursts rather than steadily, which wrecks efficiency and wears the compressor. It also costs you more up front, so the incentive runs the wrong way.
Warning signs at survey stage:
- A quote produced from a phone call, a floor plan, or your EPC rather than a site visit
- Sizing based on the output of your existing boiler, which was almost certainly oversized itself
- No discussion of insulation, or an insistence that it makes no difference
- No interest in where the hot water cylinder will go
- No mention of the electrical supply or a DNO application, which is usually needed before installation
Reading the quote
Compare quotes on the figure before the grant. That is the only number that tells you what the work is actually being priced at, and it is the one that varies. A quote that only shows you the post-grant price is hiding the comparison.
What a good quote contains:
- The room-by-room heat loss calculation, as an attachment or appendix. Ask for it if it is not there
- The design flow temperature. Lower is better. A system designed at 55°C with no radiator changes usually means the calculation was not done properly
- An itemised radiator schedule, saying which radiators are being changed and to what. “Radiator upgrades as required” is where quotes quietly expand later
- The predicted seasonal efficiency, with a realistic figure rather than the manufacturer’s datasheet number
- The cylinder, its capacity and where it goes
- The grant itemised explicitly, showing the deduction rather than mentioning it vaguely as something to be sorted out later
- What financial protection is included
- Who is doing the work. Directly employed engineers or subcontractors, and who holds the MCS certification
Questions that separate good from bad quickly
- What flow temperature is this designed around, and what did the heat loss calculation come to? A good installer answers with numbers, immediately.
- What seasonal efficiency should I realistically expect? Anyone unwilling to put a figure in writing is telling you something.
- Which radiators are you changing and why those? “None” is occasionally correct and usually a warning.
- How many heat pump installations have you completed in the last twelve months? Recent volume matters more than years in business. A firm that fitted boilers for thirty years and heat pumps for three months is learning on your house.
- Can I speak to a customer you installed for last winter? Not a testimonial on the website. A real one, ideally one who has been through a full heating season.
Red flags
Pressure to sign today. Discounts that expire at the end of the visit are a sales technique, not a price. No legitimate installer needs your signature that afternoon.
Cold contact. If they approached you rather than the other way round, be cautious. Genuine schemes do not need to phone you, and “you qualify for a government grant” is the opening line of a great many scams.
Large deposits. A modest deposit is normal. Anything approaching half the contract value before work starts is not, and it is exactly the situation financial protection exists to cover.
Vagueness about the grant. The grant must be shown as a deduction on the quote and the final invoice. Installers are explicitly barred from asking you to hand the grant value over to them.
Reluctance to give an MCS number. There is no good reason for this.
If it goes wrong
Raise it with the installer first, in writing. Under MCS rules they are expected to respond promptly, and most problems are resolved at this stage.
If that fails, where you go next depends on which scheme they are on. For installers certified to the redeveloped scheme, complaints go to MCS directly, which now operates a centralised complaints process with a regulated ADR route. For installers still on the old scheme, the route runs through their consumer code, RECC or HIES.
Beyond that, the financial protection product or insurance-backed guarantee covers the situations where the installer cannot or will not put things right, including insolvency and design failure. This is why establishing at quote stage what protection you have matters, rather than discovering it when you need it.
Frequently asked questions
These come up most often once people start getting quotes in.
Does my installer have to be MCS certified?
For the Boiler Upgrade Scheme, yes, absolutely. Without MCS certification there is no grant. You can legally have a heat pump fitted by an uncertified installer, but you forfeit £7,500 and the consumer protections that come with the scheme.
Do they still need to be RECC or HIES members?
Not necessarily, and this is the bit that has changed. Installers certified to the redeveloped MCS scheme can deliver Boiler Upgrade Scheme work without consumer code membership, because DESNZ has recognised the scheme’s own consumer protections. Installers still on the old scheme do need it. Ask which applies.
How many quotes should I get?
Three. Compare them on the pre-grant price, the design flow temperature and the heat loss figure rather than on the headline total.
Should I use a national company or a local one?
Neither is reliably better. National firms often have shorter lead times and standardised processes; local firms are often easier to get back when something needs adjusting in February. Judge on the survey and the quote, not the size.
What if the installer goes out of business?
That is one of the specific situations covered by the mandatory financial protection product under the redeveloped scheme, or by an insurance-backed guarantee under the old one. Confirm which you have before you pay a deposit.
Can I get the grant if I do some of the work myself?
No. The installation must be carried out by the MCS-certified business, which then certifies it and applies for the grant on your behalf.
Last updated 13 September 2026. Scheme details verified against MCS and DESNZ announcements on the redeveloped installer scheme. The MCS transition is ongoing and requirements differ depending on which scheme an installer has moved to, so check the date above and confirm the current position with MCS directly. Written by Ben Jardine.