A heat pump is easier to plan than to rush. The survey, the design and the grant application each take some time, and none of them can be skipped without a cost somewhere. But a breakdown does not rule a heat pump out. It means choosing between two routes, knowing what each one risks.
The two routes after a breakdown
| Normal route | Retrospective route | |
|---|---|---|
| When the grant is applied for | Before the work | After commissioning, within 120 days |
| Your confirmation to Ofgem | Within 14 days of its email | Still needed when the application is made |
| If the grant is refused | You find out before work starts | The work is done; you pay the full price |
| Time without the heat pump | Survey, design and approval first | Shorter, if the installer can start at once |
The normal route, done quickly
The normal route is the same as any installation: survey, design and quote, then the installer applies and you confirm when Ofgem emails you. The way to keep it quick is to remove your own delays. Answer Ofgem's email the day it arrives rather than near the end of the 14 days. Agree the cylinder position and the outdoor unit's spot at the survey. Check early whether the unit meets the planning conditions, because an application would add weeks. Once the voucher is issued, the installer has 3 months to finish an air source job, so there is no reason for the fitting itself to wait.
The installation planner shows the dates that follow from the month you accept a quote.
The retrospective route
The scheme lets an installation go ahead first and the grant be applied for afterwards, as long as the application is properly made within 120 days of commissioning. That is the route people consider after a breakdown, because the heating comes back sooner.
Ofgem's guidance is plain that this carries extra risk for the owner. If the application is refused, for example because something about the property or the installation does not meet the rules, the grant is not paid and you are left with the full cost. At the July to September 2026 median, that is the difference between paying £12,826 and about £5,326. Only the installer can ask Ofgem to review a refusal, within 28 days.
If you take this route, ask the installer before work starts, in writing: what happens to the price if the grant is refused? Some will have a view on how likely a refusal is for your home; none can guarantee the outcome.
Staying warm in the meantime
Where the normal route is chosen, the gap is usually bridged with temporary heating, such as electric heaters, and hot water from an electric immersion heater if the home already has a cylinder. These are expensive to run for long, so the aim is to keep the gap short: answer Ofgem quickly and agree the fitting date as soon as the voucher is issued. Another option some people use is a repair to the old boiler to buy time, where a repair is possible and safe.
Deciding
The choice comes down to how long you can manage with temporary heat, and how much of the grant you are prepared to put at risk. A short wait on the normal route keeps the grant decision ahead of the spending. The retrospective route brings the heating back sooner but moves the risk of refusal onto you. Whichever you choose, the survey still matters: a heat pump sized in a hurry is a heat pump that may not keep the house warm. The survey page explains what it should cover, and the installation stages page shows the normal order.