Heat Pump Disadvantages: The 7 Real Downsides (and How to Avoid Them)

A heat pump costs more to buy and fit than a like-for-like boiler swap, because it needs an outdoor unit, a hot water cylinder and a design based on your home's heat loss. The Boiler Upgrade Scheme takes £7,500 off (£9,000 off the gas grid), and after the grant our installed prices typically range from £1,500 to £6,500 depending on the size of the home. 0% finance can spread the rest.

Electricity costs more per unit than gas, so a heat pump only saves money if it runs efficiently. Efficiency is measured as SCOP — how many units of heat you get per unit of electricity over a year. A well-designed system running at low flow temperatures, on a heat pump tariff, is typically cheaper to run than an old gas boiler. A badly set-up one, running too hot or on the wrong tariff, can cost more. See our guide to heat pump running costs.

Heat pumps work best at lower flow temperatures (around 35–55°C) than a gas boiler (65–75°C), so rooms where the radiator is too small for the heat loss may need a larger one — typically £150–£400 per radiator. A room-by-room heat loss survey shows exactly which ones; many newer, well-insulated homes need none.

The outdoor unit needs a spot with good airflow, and most systems need a hot water cylinder indoors. If you have a combi boiler today, finding room for a cylinder is often the biggest practical hurdle.

Outdoor units typically run at around 40–55 dB at one metre — similar to a quiet dishwasher. In England the old 1-metre boundary rule was removed on 29 May 2025; instead, the installation must pass the MCS 020(a) noise assessment (37 dB(A) at the neighbour's nearest door or window) to count as permitted development. See the best side of the house for a heat pump.

A heat pump works best running low and steady for longer periods, rather than blasting heat on and off like a boiler. Radiators feel warm rather than hot, and turning the thermostat right down overnight can cost more than it saves. Once people get used to this, most find the house more evenly comfortable.

Most bad heat pump stories trace back to design: a unit that's the wrong size, pipework or radiators that weren't checked, or flow temperatures set too high. Before you commit, ask any installer for a room-by-room heat loss calculation, the design flow temperature, the expected SCOP and their MCS certificate number.

Modern air source heat pumps keep working well below freezing, and UK winters sit comfortably within their operating range. Efficiency dips on the coldest days, which the design accounts for.