Heat Pump vs Air Conditioning: Same Machine, Different Job
The secret the naming hides: modern air conditioning IS a heat pump. The real choice is air-to-air (cools + heats rooms) versus air-to-water (replaces your boiler). Here's how to pick.
The comparison that actually matters
"Heat pump vs air conditioning" sounds like a technology choice. It isn't — both run the same refrigeration cycle. The real decision is what you want heated or cooled:
| Air-to-air (air conditioning) | Air-to-water heat pump | |
|---|---|---|
| Cools in summer | Yes — its headline job | Rarely (some can, weakly, via emitters) |
| Heats rooms | Yes, COP 3–4, per room | Yes, whole house via radiators/UFH |
| Hot water | No | Yes |
| Installed cost | £1,400–£3,200 single room; £3,500–£8,500 multi-room | £8,000–£15,000 before grant |
| Current grants | £2,500 for qualifying residential systems | £7,500 for qualifying systems |
| Install time | Usually a day | Several days, plus system design |
| Replaces your boiler | No (works alongside it) | Yes — that's the point |
When air-to-air (air conditioning) is the right call
You actually want cooling. UK summers now hit 30–40°C most years, and an air-to-water heat pump will not rescue a 28°C bedroom. If sleeping through heatwaves is the goal, air-to-air is the only one of the two that does the job.
You want efficient heat in specific rooms. Home office, loft conversion, garden room or the living room you actually use—zonal heating can avoid warming every radiator. Use the air-conditioning heating guide and calculator with your own tariff rather than relying on a national claim.
You want a simpler installation. A straightforward single split often installs in a day for £1,400–£3,200. Read our air-to-air heat-pump cost and £2,500 grant guide before assuming a cooling-led installation qualifies. No radiator upgrades or cylinder swap are normally required.
When an air-to-water heat pump is the right call
You're replacing a boiler. If the gas boiler is end-of-life and you want off fossil heating, air-to-water with the £7,500 grant is the route — that's exactly what the scheme exists for.
Whole-house heating and hot water matter more than cooling. Radiators, underfloor heating, cylinder — one system, properly designed.
The quiet third option: both
Increasingly common: air-to-water carries the heating and hot water, one or two air-to-air splits handle summer cooling and shoulder-season top-up in the most-used rooms. The systems don't conflict — and the air-to-air half is the cheap, one-day part of the pair.
Frequently asked questions
Is air conditioning the same as a heat pump?
Mechanically, yes — both move heat with a refrigeration cycle. A modern split-system air conditioner is an air-to-air heat pump: run one way it cools the room, reversed it heats it. The thing most people mean by "a heat pump" in the UK is an air-to-water unit that heats radiators and hot water instead of blowing air.
Should I get air conditioning or an air source heat pump?
Different jobs. Want cooling in summer and cheap supplementary heating for key rooms? Air-to-air (air conditioning) — installed in a day from around £1,400. Want to replace your gas boiler and heat the whole house plus hot water? Air-to-water heat pump — a £8,000–£15,000 project before the £7,500 Boiler Upgrade Scheme grant. Plenty of homes sensibly end up with both.
Does the Boiler Upgrade Scheme apply to air-to-air heat pumps?
Yes. Current GOV.UK and Ofgem guidance lists a £2,500 grant for qualifying residential air-to-air systems in England and Wales; qualifying air-to-water systems receive £7,500. The system must replace existing fossil-fuel or electric heating, meet the full space-heating requirement and use an MCS-certified installer, so a cooling-led bedroom installation should not be assumed eligible.
Can air conditioning heat a whole house in winter?
It can heat the rooms it serves very efficiently (3–4kWh of heat per 1kWh of electricity), and a multi-split covering main rooms can carry most of a mild winter. What it cannot do is heat radiators or hot water, so most UK homes running air-to-air keep the boiler for water and deep-winter backup.
Which is cheaper to run for heating?
Efficiency is similar — both are heat pumps with COPs around 3–4. Air-to-air often edges ahead in practice because it heats the rooms you are using rather than the whole system of radiators. The real running-cost comparison is against what you have now: either type beats electric radiators roughly three-to-one, and both are competitive with mains gas at 2026 prices.
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