How Air Source Heat Pumps Work
An air source heat pump extracts heat from outside air, even in freezing conditions, and concentrates it into your heating and hot water system. It does not create heat by burning fuel; it moves heat that already exists. That is why a correctly installed system produces several units of heat for every unit of electricity it consumes.
The technology is proven across Scandinavia in winters far colder than ours. In the UK, the difference between a system that works and one that doesn't is not the technology. It is the installer.
Performance & Efficiency (COP Ratings)
COP, Coefficient of Performance, is the number that matters. A COP of 3.5 means 1kWh of electricity in, 3.5kWh of heat out. A correctly sized and commissioned system from us runs at a COP of 3.0–3.5 across the season. A badly installed system can run at close to 1.0, which is when heat pumps cost more than gas and end up in one-star reviews.
Heat Geek accredited installations are more than 30% more efficient than the national average, and every one carries a 2-Year Performance Guarantee, the only guarantee in the industry that covers performance, not just parts. If the system does not operate at or above the efficiency quoted, we fix it free of charge.
System Sizing & Installation Process
Every installation starts with the full heat loss survey. The system is sized against your house's measured heat loss, never a bracket, never a brochure. Your fixed written quote shows the gross cost, the £7,500 BUS grant, and the net price you pay as three separate line items. Installation typically takes three days. Your named engineer installs, commissions, registers the system for MCS certification and hands over on the final day.
Winter Performance & Running Costs
We monitor every heat pump we fit, so the efficiency it actually runs at is a number you can see rather than a promise. Our completed installs are running at seasonal efficiencies of 3.9 to 4.8, well above the UK average and far beyond a gas boiler. Your survey report includes a running-cost projection built from your own heat loss figures, and you can see the real readings for yourself on our winter performance page.
Radiator Upgrades & Compatibility
Heat pumps run at lower flow temperatures than gas boilers, so some rooms need larger radiators to deliver the same warmth. Where that is true for your house, the survey identifies it and the upgrades are included in the same fixed quote and installed in the same project, no second contractor, no coordination overhead. See the full detail on our radiator upgrades page.
You Do Not Need Loft Or Cavity Wall Insulation To Qualify
This used to be true. It isn't any more, and most quotes you'll read online haven't caught up. The requirement to act on your EPC's insulation recommendations was dropped in 2024, and in April 2026 the requirement to hold a valid EPC at all was removed. The government estimated that change alone saves a typical semi around £2,500.
Insulation still helps: a better-insulated house needs a smaller, cheaper heat pump running at a lower flow temperature. But it is not a condition of the £7,500 grant. If someone has told you that you must insulate first, they're working from old rules. Check the current rules on gov.uk →
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