If you’re currently undergoing a home renovation project, you may be considering your heating needs. Whether it’s a home renovation or a garden room project, heating is a key factor in the grand scheme. I’ve recently tackled both of these projects. A fully insulated garden room and a home renovation project that both required efficient heating systems.
Heating might have felt like a background decision early on, but as the project evolves, this decision suddenly becomes central, not just for comfort but for whether these new spaces are genuinely usable all year round.
For a growing number of UK homeowners, myself included, the answer increasingly points towards heat pumps. The £7,500 Boiler Upgrade Scheme helps make the idea more attractive financially, but just as importantly, a renovation or garden room project is often the perfect time to consider it. You are already opening up floors, thinking about pipe runs, and working out how heat will flow between the main house and any new spaces you are creating.
That said, the first heat pump quote can be a bit of an eye opener. It looks very different from a typical boiler quote, and it is not always clear what is included or what might have been left out. After spending time speaking with installers and looking into the details myself, it became obvious that there are a few key things worth checking before making a decision.
Here’s what I would look out for before committing.
Table of Contents
The Quote Should Reference a Heat Loss Calculation
This is the single most important thing to look for. A heat pump runs at lower flow temperatures than a gas boiler, which means the system has to be sized precisely for the property. The only way to do that accurately is a room-by-room heat loss calculation that accounts for wall construction, glazing, insulation levels, ventilation, and floor area.
If the quote you’ve received doesn’t reference a heat loss survey, the installer is estimating. That estimate might be close enough for a straightforward new-build, but for a renovation project where insulation standards vary between the original structure and newer additions, it’s a gamble. An undersized system won’t heat the house properly. An oversized one will cycle inefficiently and cost more to run. I used a free, simple heat loss calculator to estimate this myself. Here are the results based on my 4-bed detached house.
Any credible air source heat pump installation should start with this calculation. If it doesn’t appear in the quote documentation, ask why.
Every Emitter Change Should Be Itemised
Because heat pumps operate at lower temperatures, some existing radiators won’t be large enough to deliver the required output. A proper survey identifies exactly which radiators need upsizing or replacing and includes them as line items in the quote.
Watch out for quotes that list radiator upgrades as a “provisional sum” or “to be confirmed on site.” That language means the installer hasn’t assessed your emitters properly, and the cost will grow once work begins. If you’re mid-renovation with ceilings down and floors up, this is exactly the point where budget surprises hurt the most.
The same applies to underfloor heating zones. If your ground floor runs UFH and the upper floors use radiators, the system may need mixing valves to deliver different flow temperatures to different zones. That should be specified and costed in the quote, not discovered on installation day.
The Manufacturer and Model Should Be Named
A quote that says “air source heat pump, 12kW” without specifying the manufacturer and model is a red flag. Different units have different performance characteristics, noise levels, footprints, and warranty terms. You should know whether you’re getting a Viessmann Vitocal, a Vaillant Arotherm, a Grant Aerona, or something else entirely.
This matters because the unit selection should be driven by the heat loss calculation and the property’s specific requirements, not by whatever the installer has in stock or can get at the best trade price. If the model isn’t named, you can’t verify that it matches the design.
Here’s a basic comparison chart as an example.
| Attribute | Viessmann Vitocal 200-S | Vaillant aroTHERM plus | Grant Aerona³ (13 kW) |
|---|---|---|---|
| Output range | ~5.5 → 14.7 kW | ~3.5 → 12 kW (model dependent) | ~6 → 17 kW |
| Max flow temperature | ~60 °C | Up to 75 °C | ~55–65 °C (system dependent) |
| Noise level (typical) | ~30 dB(A) @ 4 m (very quiet) | ~46–48 dB(A) | ~49–55 dB(A) @ 1 m |
| Footprint / size | ~1080 × 850 × 500 mm (compact) | Larger monobloc unit (varies by model) | ~1418 × 1024 × 403 mm |
| Best use case | New builds, low-noise areas, high-spec installs | Retrofits with radiators, high-temp demand | Budget installs, simpler systems, rural/space available |
Commissioning Should Be Explicitly Mentioned
Commissioning is the process of configuring the heat pump after installation: setting flow temperatures, calibrating weather compensation, programming DHW schedules, and verifying that the system runs to the design spec. This is where the difference between a good installation and a mediocre one is made.
A surprising number of heat pump installations are left on factory default settings, which means the system runs less efficiently than it could and the homeowner ends up paying higher bills than necessary. The quote should state that commissioning is included and ideally describe what it covers. Heat pump installers like Eco Renewables commission against the original design document and walk the homeowner through the operating logic before leaving site.
If the quote doesn’t mention commissioning at all, the installer may be planning to switch it on and leave.
The Grant Application Should Be Handled for You
The Boiler Upgrade Scheme provides £7,500 toward qualifying heat pump installations in England and Wales. The installer applies for this on your behalf through the MCS certification system. The grant is then deducted directly from the invoice, so you never pay the full gross amount.
Your quote should show both the gross cost and the net cost after the grant deduction. If it only shows the net figure, ask to see the breakdown. You want to know what you’re paying for before the grant is applied, not just the final number.
Eligibility requires a valid EPC, an existing fossil fuel heating system being replaced, and an MCS-certified installer. If any of these conditions aren’t met, the grant won’t be approved, and you’ll be liable for the full amount. A good installer confirms eligibility before quoting.
Aftercare and Warranty Terms Should Be Clear
Heat pump systems need a service in the first year and ongoing maintenance thereafter. The quote should specify what’s included post-installation: whether the first service is covered, what the workmanship warranty period is, and what the manufacturer warranty covers.
Some installers include 12 months of support and the first annual service. Others hand over the keys and move on. The difference matters, particularly in the first heating season when the system may need fine-tuning as temperatures drop and the house behaves differently than the design models predicted.
I wanted to know the system was going to be the right fit for the long run, and the service partner selected was able to maintain the system for many years to come. Ask specifically: if the system needs adjusting in the first winter, is that covered? If the answer is vague, factor that risk into your decision.
The Bottom Line
A heat pump is not a like for like boiler swap. It is a system design decision, and the quote tells you a lot about how carefully that has been thought through.
Going through this process myself, it became clear that the detail matters. If you are mid renovation, take the time to question what is included and what is not. The cheapest option can leave gaps, and a higher price does not always mean a better outcome. The best quote is the one that makes the thinking behind it clear.
