Are Second-Hand Heat Pumps Worth It? Why Used Units Rarely Make Sense

Quick answer: Almost never. The £7,500 Boiler Upgrade Scheme grant only applies to heat pumps that have never been used, so buying second-hand forfeits the biggest discount available — before you count the lost warranty, the cost of professional refrigerant handling, and the strong odds that a unit sized for someone else’s house is wrong for yours.

The grant rule that kills the maths

The Boiler Upgrade Scheme is explicit. The scheme’s regulations require that no heat-generating part of the pump “was used before the plant was first commissioned” (Boiler Upgrade Scheme Regulations 2022, regulation 9). A second-hand unit fails that test outright, and since only installers certified under MCS can apply for the grant on your behalf (GOV.UK), there is no route around it: used unit, no grant. That single rule removes £7,500 from the second-hand side of the ledger in England and Wales — and from 21 July 2026 the gap is even wider for homes currently heated by oil or LPG, which qualify for an uplifted £9,000 grant until 31 March 2027.

Run the numbers

Our modelled national mid-point installed cost for a heat pump is £11,014 (how we calculate costs). With the £7,500 grant, that is a net outlay of around £3,500 for a new, warrantied, MCS-certified installation. Now price the second-hand route honestly:

Installation labour, the cylinder, pipework and controls make up a large slice of any heat pump project, and none of it gets cheaper because the box is used. So the used unit has to be nearly free to compete with roughly £3,500 net for new — and it still loses on everything below the price line.

The problems money can’t see

• Sizing. That unit was (ideally) sized for a specific house via a room-by-room heat-loss calculation. The chance it matches your home’s heat loss is small — and both oversizing and undersizing cost you every month. See what size heat pump properties need.
• Unknown history. Compressor wear is invisible. You cannot tell whether a unit spent five years short cycling on a botched installation, and there is no MOT for heat pumps.
• Warranty. Manufacturer warranties typically do not survive removal and reinstallation, and are rarely transferable to a second owner — check any brand’s terms and our warranty comparison before assuming otherwise.
• Installer reluctance. Reputable MCS installers will rarely agree to fit a used unit: they cannot certify its condition, and their workmanship guarantee would sit on top of hardware they cannot vouch for.
• Refrigerant vintage. Older units use refrigerants that are being phased down in the UK, which can make future repairs and regassing harder and dearer.

A note on geography: the Boiler Upgrade Scheme covers England and Wales only. In Scotland the equivalent support runs through Home Energy Scotland’s grant and loan scheme instead — the scheme rules differ, but the practical conclusion is the same, because that funding is likewise tied to professional, standards-compliant installation of new equipment rather than salvaged units.

Are there any exceptions?

A genuinely unused unit — surplus stock, a cancelled project, still boxed — is a different conversation, since the regulation turns on the pump having been used, not on who owned it; even then, eligibility rests on your installer confirming the specific case with Ofgem, and many will simply prefer supplying new. Off-grid workshops, outbuildings and hobby projects where no grant would apply anyway are the other honest use case for cheap used hardware — with eyes open about lifespan and maintenance costs.

The better route to a cheap heat pump

If the appeal of second-hand is price, note that the grant already does the discounting: roughly £3,500 net (our modelled estimate) buys a new system with a warranty, a workmanship guarantee and scheme-compliant paperwork. Get the real number for your home with our cost calculator, read up in our heat pump guide, and when the quotes come in, spend your negotiating energy on system design rather than salvaged hardware.

FAQs

Can I buy a used heat pump and have an MCS installer fit it?

You can ask, but expect a no. The installation itself could not qualify for the Boiler Upgrade Scheme because the unit has been used, and most MCS installers will not put their workmanship guarantee on hardware of unknown condition.

What about ex-display or end-of-line units?

An unused ex-display or end-of-line unit is not second-hand in the sense that matters to the scheme — the regulation turns on prior use, not prior ownership. Have your installer confirm eligibility with Ofgem before relying on it, and make sure the manufacturer warranty will start from your commissioning date.

Do second-hand heat pumps at least help the environment?

Reuse sounds green, but a unit that is wrongly sized or worn runs at lower efficiency for years — and heat pump carbon savings come overwhelmingly from operation, not manufacture. A correctly sized new unit usually wins on lifetime carbon as well as cost.