How to Compare Heat Pump Quotes: What a Fair Quote Looks Like

Why Heat Pump Quotes Vary So Much

Gas boiler quotes are easy to compare because the job is roughly the same everywhere: take the old one off the wall, put a new one up. Heat pump quotes aren't like that. Two installers can look at the same three-bed semi and propose different sized units, different cylinders, a different number of radiator swaps and a different flow temperature, and every one of those choices changes both the price today and your running costs for the next twenty years.

So don't be surprised if your quotes are a few thousand pounds apart. That's normal. What isn't normal is quotes that differ because one installer skipped the design work. The cheapest quote is often the one that hasn't worked out what your house actually needs, and you find that out in January.

The goal isn't to find the lowest number. It's to find the quote where you can see exactly what you're paying for, and where the design is good enough that the heat pump will run efficiently. A well-designed system at £4,500 after the grant beats a badly designed one at £3,000 every single winter.

What a Proper Quote Must Include

This isn't us being fussy. Most of what follows is written into MCS's own rules. MCS publishes Guidance for Contracts and Quotations and the heat pump design standard (MIS 3005-D, Issue 3.0, mandatory since 5 December 2025), and between them they spell out what you're entitled to see.

Before you sign

• The installer's MCS certification number. MCS says a quote should include it. No number, no grant, because Ofgem only accepts Boiler Upgrade Scheme applications from MCS certified installers.
• The exact make and model of heat pump, with its output in kW, plus the manufacturer's datasheet. "7kW air source heat pump" isn't enough. You want "Vaillant aroTHERM plus 7kW" or similar, so you can look it up.
• The hot water cylinder: make, model and size, plus its datasheet. Most homes coming off a combi will need one.
• A performance estimate. MIS 3005-D requires the installer to give you an estimate of the system's annual energy performance, along with a Key Facts sheet, before the contract is awarded. This is where the predicted running cost comes from.
• A full cost breakdown covering labour, materials and equipment, with the total including and excluding VAT.
• The Boiler Upgrade Scheme grant shown as a deduction. gov.uk is explicit: the grant "will be taken off the amount you pay for installation. This will be shown on your quotation and invoice."
• The deposit, any staged payments, and how the deposit is protected. MCS lists all three as things a quote should contain.
• Warranties and guarantees, and how long each lasts: the heat pump, the cylinder and the installer's own workmanship.
• Timings: how long the job takes and when it can start.
• How long the quote is valid for.
• Any subcontractors who'll do part of the work. MIS 3005-D requires them to be named up front.

Before the work starts

Some of the detailed design can come after you've agreed the contract, but MIS 3005-D says you must have it in writing before installation begins:

• The heat loss of every room, in W/m². This is the proof that someone did a room-by-room calculation rather than guessing from the floor area.
• The design flow temperature: the temperature of the water leaving the heat pump.
• The SCOP at that flow temperature, taken from the MCS website.
• The type and size of every radiator (or other emitter) in the system.
• Your calculated daily hot water demand and the recovery rate of any new cylinder.

If the design changes the estimated performance or the agreed spec, the installer has to give you an updated estimate, a written variation to the contract, and the chance to cancel without further cost. That's worth knowing if the survey turns up something unexpected.

The one question that sorts good installers from bad: "What's the design flow temperature, and what's the SCOP at that temperature?" A good installer answers straight away, usually something in the 35°C to 50°C range. Someone who says "it'll be fine" or talks about 60°C is telling you the system hasn't really been designed.

A Worked Example: Reading a Quote Line by Line

Here's what a sensible quote for a typical three-bed semi, currently on a gas combi, might look like. The figures sit inside the ranges in our heat pump costs guide. Yours will differ, but the structure is what you should be looking for.

Two things jump out when you read quotes this way. First, the heat pump itself is well under half the cost, so a quote that looks cheap because of a cheaper unit may have cut corners somewhere much more important. Second, radiators are where quotes diverge most. One installer says you need six new radiators, another says two. The room-by-room heat losses are how you settle it. See do I need new radiators for a heat pump for what's genuinely needed.

If you only have one quote and can't tell whether it's fair, that's exactly the point of getting a second. Get another quote from MCS installers near you and lay them side by side against this table.

Red Flags That Should Make You Walk Away

• No survey, or a quote from photos alone. A room-by-room heat loss calculation needs measurements from every room. Someone who quotes you a fixed price over the phone hasn't done it, and the MCS standard says the building has to be assessed by a competent professional experienced in heat pump systems.
• A unit that's much bigger than the others are quoting. If two installers say 6kW and one says 12kW, ask why. The standard requires the heat pump to cover at least 100% of the calculated heat load, but a unit well above that costs more to buy and tends to cycle on and off, which hurts efficiency.
• A high flow temperature with no explanation. If the design goes above 55°C, MIS 3005-D says the installer should also give you an alternative design at 55°C or lower and explain the differences in efficiency and energy use so you can choose. If they haven't, ask for it.
• The grant isn't on the quote. The £7,500 should appear as a deduction. "Pay us the full amount and claim it back" is not how the scheme works.
• A big deposit. The Renewable Energy Consumer Code's advice is plain: never pay more than 25% of the contract price up front, and check it'll be protected.
• Pressure to sign today. "This price is only valid if you sign now" is a classic. RECC's guidance is not to sign if you're offered a discount to sign or pressured in any way, and it calls that practice illegal. And the MCS Customer Commitment says installers must not pressure you.
• A running cost promise tied to one tariff. MCS requires installers to warn you not to sign a contract based on specific energy prices, because tariffs change.
• Buffer tanks, extra controls or "premium" add-ons that the others haven't included and nobody can justify. Ask what each one does for your house specifically.

How to Check an Installer Is MCS Certified

Don't take the logo on the van as proof. MCS has a free Find an Installer tool where you can search by company name or certification number. Check three things:

1. The company is listed and the certification is current.
2. It's certified for air source heat pumps specifically, not just solar.
3. The name and number match what's on your quote.

Also ask whether they're a member of a consumer code, RECC or HIES. This used to be automatic with MCS, but it isn't any more: under MCS's redeveloped installer scheme, which most installers are moving onto during 2026, consumer code membership is no longer mandatory. Many installers have kept it anyway. Members of RECC must insure deposits, stage payments and the workmanship warranties they issue, so you're covered if the firm stops trading.

In place of the consumer code, the redeveloped scheme makes every installer buy an MCS approved financial protection product on your behalf. It pays to put right a faulty installation if the original installer won't or can't (because it's gone bust, say), lasts at least six years from completion, and the excess is capped at £250. That's good cover for the work itself, but it's about fixing the installation, not refunding a deposit. So whichever scheme your installer is on, ask them to explain in writing how your deposit is protected. MCS says they have to tell you, and the quote should name the financial protection product too.

Our installer directory lists MCS certified heat pump installers by area, which is a quick way to find a second or third firm to compare against.

Questions to Ask Every Installer

1. Can I see the room-by-room heat loss figures?
2. What's the design flow temperature, and what's the SCOP at that temperature?
3. Which radiators need replacing, and why those ones?
4. Will you set up weather compensation, and will you come back and tune it after the first cold spell?
5. Where will the outdoor unit go, and have you done the noise check for permitted development? (In England and Wales the limit is 37.0 dB LAeq,5mins, measured 1m outside a neighbour's habitable-room window or door; see our noise guide.)
6. Who applies for the Boiler Upgrade Scheme grant, and when?
7. How much deposit do you need, and how is it protected?
8. What warranty comes with the heat pump, and is the workmanship warranty insurance-backed?
9. Is the first service included, and what does an annual service cost after that?
10. Do you use subcontractors for any part of the job?

A good installer will be pleased you asked. The ones who get defensive have usually just told you something.

Why Three Quotes, Not One

Both MCS and RECC say it: get at least three quotes. With one quote you have nothing to measure against. With two, you know they're different but not which one's off. With three, patterns show up. If two installers say 7kW and three radiators, and the third says 12kW and eight radiators, you know which one to question.

Watch out for what we'd call quote fatigue. After the second survey visit it's tempting to go with whoever feels easiest. Don't. The difference between a good and a mediocre design can easily be a couple of hundred pounds a year in running costs, every year for the life of the system.

If you're weighing up a big supplier's fixed-price package against local firms, read our Octopus heat pump review first. National packages can be good value, but you should still compare them against at least one independent quote.

The Checklist

Print this, or keep it open on your phone while you go through each quote. Every box should be ticked before you sign.

• ☐ Installer's MCS certification number is on the quote, and checks out on the MCS website for air source heat pumps
• ☐ Exact heat pump make, model and kW output, with datasheet
• ☐ Hot water cylinder make, model and size, with datasheet
• ☐ Performance estimate and Key Facts sheet supplied before signing
• ☐ Itemised costs: unit, cylinder, radiators, labour, electrics, pipework
• ☐ £7,500 Boiler Upgrade Scheme grant shown as a deduction, installer applying
• ☐ Deposit no more than 25%, with written details of how it's protected
• ☐ Warranties listed: heat pump, cylinder and workmanship, with lengths, plus any MCS approved financial protection product named
• ☐ Start date, job length and quote validity period
• ☐ Any subcontractors named
• ☐ Room-by-room heat losses, flow temperature and SCOP promised in writing before work starts
• ☐ No pressure to sign, and cancellation rights explained

After You've Chosen

Once you've agreed a quote, the installer applies for the grant on your behalf and Ofgem contacts you to confirm the installer is acting for you. Don't ignore that email or call, because the voucher won't progress without it. After installation, the installer should register the job and send you an MCS certificate. MIS 3005-D gives them 10 working days after commissioning, and installers on MCS's redeveloped scheme get 30 days, so chase it if you've heard nothing after a month. Keep it with your handover pack, as you'll need it to sell the house and for any export tariff if you add solar later.

Timing matters too. Ofgem's rules say the heat pump must be commissioned no more than 120 days before the voucher application is made, so the grant must be applied for before or shortly after the install, never long after. A good installer will sort this out as a matter of course. For the full process, see our Boiler Upgrade Scheme guide.