Air source heat pumps vs gas boilers: the honest comparison.

A gas boiler burns fuel and can push water round your radiators at 60, 70 or 80 degrees without caring much about efficiency. A heat pump does something completely different. It moves heat from the outside air into your home, and the harder you make it work, the less efficient it becomes.

Efficiency is measured as a coefficient of performance. At a flow temperature of 35 degrees, a good air source heat pump delivers roughly 4 units of heat for every unit of electricity. Push the same unit to 55 degrees and that can drop to around 2.5. Since electricity costs more per unit than gas, the entire running cost argument comes down to whether your home can be heated at a low flow temperature.

This is the reason we talk about emitters before we talk about heat pumps. Get the emitters right and a heat pump comfortably beats a boiler on running cost. Get them wrong and it will not.

Layer on the £7,500 Boiler Upgrade Scheme grant and the capital gap narrows sharply. Our Boiler Upgrade Scheme guide sets out exactly how that works and who qualifies.

A radiator heats a small surface area to a high temperature. Underfloor heating heats an enormous surface area, your whole floor, to a low temperature. For a heat pump, the second approach is transformative. It is the difference between the system working at the top of its efficiency curve and struggling at the bottom of it.

The objection is always the same: we do not want the floors lifted. In an occupied home that is a fair objection, and it is exactly why retrofit floor milling exists. We cut precise channels into the existing concrete or screed with dust extracted equipment, lay the pipe into those channels and reinstate. The floor level barely moves, doors and skirtings stay as they are, and there is no rebuild.

Where milling is not viable, low profile overlay panels add around 15mm to the floor build up and achieve much of the same benefit. Both routes are covered under retrofit domestic installations, and you can see the finished work in our case studies.

If you keep radiators, expect the heat loss calculation to flag a handful of rooms needing a larger emitter. It is very rarely every room, and it is very rarely as disruptive as people fear.

• Comfort. A boiler heats in bursts, so rooms swing warm then cool. A heat pump runs steadily at a lower temperature, which most people describe as more even. With underfloor heating there are no cold corners and no hot radiator faces.
• Space. A heat pump needs an outdoor unit with clear airflow and, in nearly all cases, a hot water cylinder indoors. If you have a combi boiler and no airing cupboard, finding cylinder space is the real design challenge, not the heat pump itself.
• Noise. Modern units sit around fridge level at a few metres. Poor siting, not the equipment, causes almost every noise complaint we are called to.
• Lifespan. Roughly 15 to 20 years for a heat pump against 10 to 15 for a boiler, assuming annual servicing on either.
• Servicing. Both need yearly attention. Ours is covered under servicing and maintenance, and we carry Gas Safe registration alongside MCS, NAPIT and RECC.

Heat pumps reward being left alone to run steadily and punish being switched on and off like a boiler. Zonal control with proper weather compensation lets each room hold its own setpoint while the system stays at a low flow temperature. That is why we fit smart thermostats and zonal control as part of the design rather than as an afterthought. A well controlled heat pump and a badly controlled one can differ by a fifth on annual running cost with identical hardware.

Choose a heat pump if you are off the gas grid, if you are already planning floor work or a renovation, if you can accommodate underfloor heating or larger emitters, and if you want to be ahead of where building regulations are heading. The grant makes the sums work far better than most people assume.

Stay with a boiler for now if your property has very high heat loss, no route to improving the emitters and no appetite for insulation work. We will say so at survey rather than sell you something that disappoints, and our consultancy and design service can set out a staged plan to get you there later.

Either way, the decision should follow a proper room by room heat loss calculation, not a rule of thumb. That is why underfloor heating quotations come back within 24 hours while heat pump quotations take 3 to 7 days. Installations themselves run 1 to 5 working days, with 2 to 3 days typical.

Get a straight answer on your property.

Book a free survey across Cheshire and South Manchester. We will calculate the heat loss properly and tell you honestly whether a heat pump beats your boiler.