Air Source Heat Pumps: The Honest Pros and Cons

Air source heat pumps have matured enormously in recent years. The current generation of R290 units — like the Vaillant aroTHERM Plus we install — operate efficiently in temperatures as low as -22°C, produce hot water up to 75°C, and run quietly enough to meet even the tightest planning noise limits.

Key advantages:

• Lower running costs — A COP of 3.5+ means roughly 6–7p per kWh of heat, cheaper than gas. • £7,500–£9,000 BUS grant — Slashes upfront cost dramatically. • 0% VAT — On both equipment and installation. • No gas supply needed — Ideal for off-gas rural properties. • Works with existing radiators — When properly designed for lower flow temperatures. • Pairs brilliantly with solar — Free daytime electricity powers your heating.

We are installers who believe in honesty. Here are the genuine challenges:

• Higher upfront cost — Even after the grant, a heat pump costs more to install than a replacement gas boiler. The payback period is typically 5–8 years. • Needs good design — A poorly designed system will underperform and disappoint. This is why we do room-by-room heat loss surveys, not quick estimates. • Some radiator upgrades may be needed — Heat pumps work best at lower flow temperatures, which means you may need larger or additional radiators. We assess this during the survey. • Outdoor unit requires space — You need about 1m² of outdoor space with good airflow. Planning permission is rarely needed (permitted development), but noise regulations must be met. • Defrost cycles — In very cold weather, the unit periodically defrosts, which is normal but can cause concern if you are not expecting it.

The single biggest factor in whether you love or hate your heat pump is how well it was designed. A Heat Geek-trained engineer will:

• Calculate heat loss for every room individually • Design for the lowest possible flow temperature • Size the cylinder correctly for your hot water demand • Set weather compensation curves accurately • Commission the system properly

This is why our customers consistently report comfort levels they never achieved with their old boiler. The heat pump itself is just a box — it is the engineering behind it that makes the difference.

Most UK homes can work with a heat pump. The best candidates are:

• Detached or semi-detached properties with outdoor space • Homes with some insulation (even basic cavity wall and loft) • Properties currently using oil, LPG, or electric heating (biggest savings) • Homes where the owner plans to stay for 5+ years

If you are unsure, our free survey will give you a clear answer — and if a heat pump is not right for your property, we will tell you honestly.