How to choose · Heating systems
How to choose a heat pump installer and check the design
Last updated 25 October 2026 · 2 sources listed · Reading time about 3 minutes
Short answer
Heat pump performance depends heavily on design and commissioning. Prefer installers who perform a room-by-room heat-loss survey, specify emitters and flow temperatures, size the unit to the load rather than to the old boiler, set controls carefully and explain servicing. Compare the design logic of each quote, not only the price, and check certification with the relevant national scheme.
Who this is for: A homeowner who has decided to explore a heat pump and must judge competing quotes and designs.
What to evaluate
Heat-loss survey
Correct sizing prevents short cycling from oversizing and cold rooms from undersizing.
How to check: Ask for the calculation and the design outdoor temperature used.
Emitter plan
Radiator output at low flow temperature decides comfort.
How to check: Request a room schedule showing existing and proposed emitters.
Design flow temperature
Lower flow temperature generally improves performance.
How to check: Ask what flow temperature the design assumes and how weather compensation will be set.
Hot water design
Cylinder sizing and reheat strategy influence both comfort and running cost.
How to check: Check cylinder volume, coil specification and any backup heater.
Commissioning and handover
A poorly tuned system can perform far below its capability.
How to check: Ask for the commissioning record and a walkthrough of controls.
Certification and warranty
Qualifications and workmanship cover affect incentives and long-term support.
How to check: Verify scheme membership and ask for written warranty terms.
Comparison
| Quote style | Good when | Watch out for |
|---|---|---|
| Survey-based design | Detailed calculations accompany the quote | May take longer and cost a survey fee |
| Rule-of-thumb sizing | Rarely | Oversized or undersized units |
| Manufacturer-led package | Standard home types | Limited customisation |
| Installer-designed bespoke | Complex homes | Quality depends on installer skill |
Decision worksheet
Rate up to three options against this guide’s own criteria. It runs in your browser and saves only on this device. It is a thinking aid, not a recommendation.
1. Have you checked each criterion?
0 of 6 criteria checked.
2. Compare options (0 = fails or unknown, 3 = meets it well)
| Criterion | |||
|---|---|---|---|
| Heat-loss survey | |||
| Emitter plan | |||
| Design flow temperature | |||
| Hot water design | |||
| Commissioning and handover | |||
| Certification and warranty | |||
| Total (max 18) | 0 | 0 | 0 |
Questions to ask before you commit
- Will you provide a full heat-loss calculation for every room?
- What design flow temperature will the system use?
- Which emitters will change and why?
- How will hot water be heated and kept safe from bacterial growth?
- Who commissions the system and sets the weather-compensation curve?
- What servicing is recommended and what does it involve?
- What is your certification and which scheme covers it?
- How do you handle snags after handover?
Typical trade-offs
Choose the installer offering the fullest design
- Upside
- Better comfort and performance
- Downside
- Slower process and possibly higher quote
Choose a manufacturer-approved installer
- Upside
- Support and extended warranties
- Downside
- Narrower selection
Choose a larger unit for safety margin
- Upside
- Handles extreme cold
- Downside
- May cycle on and off and cost more
Common mistakes
- Basing the choice on the lowest price rather than design completeness.
- Not asking for the heat-loss figures in writing.
- Allowing the old boiler's output to dictate the heat pump size.
- Skipping commissioning checks.
- Not checking whether the quote includes electrical upgrades.
Related questions
Why does flow temperature matter?
A heat pump becomes more efficient as the temperature it must deliver falls, so designing for lower flow temperature through larger emitters and good insulation helps. Higher flow temperatures work but reduce performance. Ask your installer to show the design flow temperature and how it varies with outdoor weather.
What is weather compensation?
It is a control feature that adjusts flow temperature according to outdoor temperature so the system delivers only what is needed. This improves comfort stability and performance. It needs to be set properly at commissioning. Ask whether it will be enabled and how it can be adjusted.
Should I expect a cylinder?
Most heat pumps heat water via a storage cylinder. Space for it is needed. Some designs use special coils and controls for efficient reheat, and periodic higher-temperature cycles to manage bacteria. Ask your installer about the cylinder specification and where it will fit.
What servicing does a heat pump need?
Typically there is an annual check of the outdoor unit, filters, refrigerant circuit indicators, controls and safety devices, though requirements vary by product and country. Warranties may require servicing by a qualified person, so skipping it can weaken a claim. Ask for a written service schedule before signing, find out what a visit includes and whether parts are covered, and keep each report with the commissioning record so the history is complete.
Sources and further reading
These pages were reachable when we last checked. They informed definitions and rules referred to above; they do not endorse this guide. Where rules differ by country, check the authority for your location.
- Energy Saver — U.S. Department of Energy, retrieved 27 October 2026
- Building Technologies Office — U.S. Department of Energy, retrieved 27 October 2026
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