How to choose a heat pump installer

Picking the right installer matters more than picking the right heat pump model. A good installer correctly sizes the system, gets your radiators flowing at the right temperature, and stands behind the install for a decade. A bad one leaves you with cold rooms and high running costs.

The seven questions to ask

1. Are you MCS-certified for the technology I want?

MCS certification is technology-specific. An installer can be MCS-certified for solar PV but not for heat pumps, those are different scope codes. Ask for their MCS number and verify it on mcscertified.com. Every installer in our directory is MCS-certified for at least one heat pump technology.

2. Are you registered for the Boiler Upgrade Scheme?

BUS registration is separate from MCS certification. Only BUS-registered installers can deduct the £7,500 grant from your bill. If they're not registered and tell you to "claim it back yourself", they're wrong, BUS only pays installers.

3. Will you do a full MCS heat-loss survey before quoting?

This is the litmus test. A proper survey takes 2–4 hours, room by room, measuring radiator outputs and U-values. An installer who quotes a kW size based on house size alone is guessing. Bad sizing is the single biggest cause of unhappy heat pump owners.

4. What flow temperature have you designed for?

A good installer will design for the lowest flow temperature your radiators allow, ideally 35–45 °C. Anything above 55 °C means either inadequate radiators or undersized pipework, and the SCOP (efficiency) drops fast. If they don't have an answer, push back.

5. What's the SCOP and how was it calculated?

SCOP (Seasonal Coefficient of Performance) is the heat pump's real-world efficiency over a year, not the manufacturer's lab figure. A competent installer should quote a SCOP for your specific design, somewhere in the 3.0–4.5 range. Treat anything above 5.0 with scepticism.

6. What's included, and what's an "extra"?

Ask for a line-item quote: heat pump, cylinder, buffer, controls, radiators, electrical, labour, commissioning, MCS paperwork. Common "extras" that surface later: new consumer unit, additional radiator upgrades, scaffolding, condensate drain. Get these in writing.

7. What happens if it doesn't perform?

A good installer will commit, in writing, to a flow temperature design target. Ask: "If after a full winter the system can't keep the house at 21 °C on a design day, what do you do?" The answer should be specific, adjust controls, replace radiators at no extra cost, or a clear remediation route. Vague answers are a red flag.

Red flags: walk away if you see these

• Quote without a survey. "Email us your details and we'll send a quote" usually means they're guessing the size.
• Pressure to sign today. Heat pumps are a 15–20 year investment. There's no legitimate reason to rush.
• Deposits before the BUS voucher is issued. Ofgem will reject claims where the installer took deposits too early.
• "You don't need to upgrade any radiators." Statistically unlikely. Most retrofits need at least one or two radiator changes.
• Doorstep selling or cold-call leads. The best installers are quietly booked out via word-of-mouth.
• Headline price much cheaper than competitors. Either they're missing something, or the cost will appear later as "extras".

Comparing quotes side by side

When you have three quotes, lay them out:

What the contract should say

• Designed flow temperature and the rooms that must hit a target temperature.
• Heat-loss figures and the property's design day temperature.
• The MCS scope code and the installer's MCS number.
• BUS grant amount, voucher reference, and the gross-minus-grant pricing structure.
• Manufacturer warranty length and what installer-side warranty covers.
• Commissioning and handover deliverables: MCS certificate, manufacturer commissioning report, weather-compensation settings.
• A cancellation right (you have 14 days under Consumer Contracts Regulations for off-premises contracts).

How to compare installers who quote different technologies

It's common to get one ASHP quote and one GSHP or hybrid quote for the same property, especially if you asked a broad question rather than specifying a technology. Comparing these fairly means looking past the headline price to the net cost after any applicable grant, the running cost at a realistic SCOP for each technology (not the manufacturer's best-case figure), and the disruption each install involves. A GSHP quote that looks expensive on day one can still be the better long-term choice on a rural property with no mains gas; an ASHP quote that looks cheap can turn out incomplete if it's missing radiator upgrades another installer included. Ask each installer to justify their technology recommendation against your specific property, not just quote what they happen to specialise in.

Trade bodies and accreditations beyond MCS

MCS certification is the mandatory baseline, but some installers also hold membership of trade bodies like the Heat Pump Association or manufacturer-specific accreditation schemes (Daikin, Mitsubishi, Vaillant and others run their own installer partner tiers). These aren't required, but they can indicate an installer does enough volume with a particular brand to be genuinely expert in it, useful context if you've already decided on a manufacturer. They're not a substitute for checking MCS certification and BUS registration directly, treat them as a secondary signal, not the primary one.

Reading reviews without being misled

Online reviews are useful but easy to game, a handful of five-star reviews left in the same week is a common red flag for incentivised or fake reviews. Look instead for reviews that mention specifics: the heat pump model, the flow temperature, how the survey went, whether the quote was itemised. Reviews that only say "great service, highly recommend" tell you almost nothing. If a company has no reviews mentioning heat pumps specifically despite years of trading, that's worth asking about directly, they may be new to the technology even if they're an established plumbing or heating firm.

Questions worth asking about aftercare specifically

Beyond the seven core questions, ask what happens in the first winter if something isn't quite right: is a follow-up visit included to fine-tune weather compensation, and is there a number to call that reaches someone who actually knows the install, not a generic call centre. Installers who stand behind their work are usually happy to commit to this in writing; hesitation here is worth noting alongside the technical answers you've already gathered.

After the install: what good aftercare looks like

The relationship doesn't end at commissioning. A competent installer hands over an MCS certificate, a manufacturer commissioning report showing the flow temperature and weather-compensation curve actually set, and a plain-English explanation of how to use the controls, heat pumps behave differently from boilers and most complaints in the first winter trace back to the homeowner not knowing how to operate the schedule properly.

Ask what the workmanship warranty covers and for how long, this typically runs 2 to 6 years and is separate from the manufacturer's warranty on the unit itself (commonly 5 to 7 years for the compressor, sometimes longer with an extended registration). Keep the MCS certificate somewhere safe: you'll need it if you ever claim on the manufacturer warranty, sell the property, or apply for further retrofit grants that check for existing low-carbon heating.

Book the first annual service before the installer leaves site. Skipping year one servicing is a common way small commissioning issues (an under-set weather compensation curve, an unbalanced radiator) go unnoticed until the following winter. See our guide on what installation actually involves for the full survey-to-commissioning timeline.