Air-to-air heat pumps in Croydon
An air-to-air heat pump is an air conditioner that has been told to run backwards. In Croydon we fit them in flats with no gas, loft rooms the radiators never reach and extensions that are cold in January and stifling in July. One wall unit does both jobs, and the boiler stays for hot water.
Price a heat pump
Name, number and postcode. We ring you to go through it.
- About a quarter of the cost of electric heaters
- Summer cooling built in
- Keeps your boiler for hot water
How does a heat pump heat a room from cold air?
By moving heat rather than making it. Even at 2°C the outside air holds heat, and the refrigerant in the outdoor unit absorbs it, is compressed to raise its temperature, then gives it up through the indoor coil. In summer the valve flips and heat travels the other way. The electricity runs the compressor and the fans, which is why a heat pump can deliver more heat than the power it draws.
What does a kilowatt-hour of heat cost from each source?
| Where the warmth comes from | What one kilowatt-hour of it costs |
|---|---|
| A plug-in electric heater | 26.32p |
| A gas boiler | 7.97p in gas, before the boiler's own losses |
| An air-to-air heat pump running at a seasonal efficiency of 4 | Roughly 6.6p |
The unit rates are Ofgem's price cap for October to December 2026, so they change every quarter and your tariff may differ. The efficiency of 4 is how the Energy Saving Trust describes typical seasonal performance; a real figure depends on the unit, the weather and the room. The saving against electric heaters is large. Against gas it is narrow. Sources: Ofgem; Energy Saving Trust.
Will it do the hot water and the radiators?
No. The Energy Saving Trust's position is that air-to-air systems are not typically designed to cover hot water demand, which leaves taps and showers with the boiler or the cylinder. It heats air, not water, and only in the room where the indoor unit is. That makes it a room heater of unusual efficiency, rather than a replacement for central heating in a four-bedroom house.
Which Croydon homes get the most from one?
- Purpose-built flats with storage heaters or panel heaters and no gas supply, of which this borough has thousands.
- Loft conversions and rear extensions on the end of a long radiator circuit.
- Rooms you were going to cool anyway, where the heating comes free.
- Garden offices with no heating at all.
Winter here is mild but not frost-free. Kenley Airfield, the Met Office station in the south of the borough, averages about 35 days of air frost a year, so we size for the cold mornings as well as the hot afternoons. Source: Met Office.
Is a reversible unit easier to get planning for?
Yes. Since 29 May 2025, air-to-air heat pumps in England have been able to use the permitted development rights written for heat pumps, with bigger size limits and no one-metre boundary rule. The condition is that the unit is not used solely for cooling, which a cooling-only system cannot meet. Flats, listed buildings and road-facing walls in conservation areas have their own rules, set out in the planning guide. Sources: MCS; Planning Portal.
Questions people ask
Does it still work when it is freezing?
Yes. Output drops as the outdoor temperature falls and the unit pauses now and then to defrost its coil, so a unit relied on for heating is sized with that in mind.
Is this the same as the heat pumps in the news that get a grant?
No. Those are air-to-water heat pumps feeding radiators and a cylinder. This heats the air in the room directly and can cool as well.
Can it heat two rooms?
Not through a closed door. A multi-split runs several indoor units, one per room, off a single outdoor unit.
Where these facts come from
Useful to have ready
With these we can give you a straight answer on the first call.
- Your postcode
- Flat, house or business premises
- Who owns the outside wall, if you lease or rent
- Which room, roughly how big, and which way the window faces
- Any conservation area or listing you know of
Air-to-air heat pumps beyond Croydon
After air to air heat pumps somewhere nearby? We cover the towns below, and each page explains its own planning position. The full picture is on our air conditioning in Croydon page.
Before you decide
Planning permission for air conditioning: when you need it
The permitted development conditions, with Croydon's exceptions.
Which size of air conditioner is right for the room?
A room size table, the adjustments that matter, and why bigger is not better.
How much does air conditioning cost?
Unit prices, labour, electrics, running costs and the extras flats add.
Related work
Air conditioning installation
A survey, a written price, then units, pipework and electrics fitted properly.
Home air conditioning
Bedrooms, top-floor flats and loft rooms, with heating thrown in.
Multi-split air conditioning
Two to four rooms from one outdoor unit, each on its own controller.
Conservatory air conditioning
Turns a glass room you use in May into one you use in August and January.
Elsewhere on this site
Office air conditioning
For offices where people, screens and south-facing glass make the heat.
Commercial air conditioning
Shops, cafés, salons, bars and restaurants, with the flats upstairs in mind.
Server room cooling
A unit of its own for the rack, sized from the power the kit draws.
Air conditioning servicing
A yearly check on any make, with the legal leak test where it applies.
Air conditioning repairs
Stopped cooling, dripping, iced up or flashing a code: diagnosed first.
Prefer a call back?
Leave your postcode and a line about the room, and we ring you. Or ring 020 8194 3009.