A heat pump installation has more paperwork and more decisions than a boiler swap, spread over weeks or months. This checklist puts them in order. Nothing on it is a test of the installer; it is what a well-run project produces anyway, so a good installer will expect you to ask.
Before the survey
After the survey, before accepting a quote
When the grant is applied for
During the fitting
At commissioning and handover
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What each group of items protects
The survey figures protect the price
The heat-loss figures, the size in kW, the flow temperature and the radiator schedule are the job being priced. With them in writing, a second installer can quote for the same job, and any later change to the design has to be explained. Without them, two quotes may be for different systems and you cannot tell.
The siting items protect against delay
The unit's position, the sound calculation and the planning position decide whether an application is needed. Finding that out after the voucher is issued eats into its 3 months; finding it out at the survey costs nothing.
The grant dates protect the grant
The 14-day consent window and the voucher's end date are the two points where a missed email or a slipped schedule can cost the grant. Both are easy to diary and hard to recover once passed.
The handover papers protect the future
The certificate, records and warranties are what a buyer, an engineer or a warranty claim will ask for. Collecting them on the day is far easier than chasing them a year later.
Why each stage matters
The first two stages decide the price and the design, so they matter most: once you have accepted a quote, the installer applies for the grant and the clock starts. The middle stages are about not missing a date, the 14 days to confirm and the voucher's deadline. The last stage is about holding the evidence you will need later, when you sell the house or call an engineer. The installation stages page explains the order, and the planner works out your own dates.
Using it with an installer
It can help to send the second section to each installer before their survey visit, so they know which figures you will ask for. Installers who already produce a full design pack will have most of it ready; the gaps tell you something too. Keep a copy of each installer's answers alongside their quote, so that when you compare prices you are comparing the same list of work.
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Keep the finished list with the commissioning certificate and the MCS paperwork: it is a quick record of what was agreed, and when, if a question about the job comes up later.