Guide · Updated 8 November 2026
Hot air heating systems and air to air heat pumps
Old hot air (warm air) heating systems, common in 1960s and 1970s UK homes, burn gas or use electricity in a central unit and push warm air through ducts to grilles in each room. A ducted air to air heat pump does the same job using a heat pump, typically making about three to four times as much heat per kWh of electricity, and can cool as well.
Recognising a warm air system
- A large cabinet heater, often in a hall cupboard or the middle of the house
- Grilles in floors, walls or skirting rather than radiators
- Common brands of the era include Johnson & Starley
Replacement options
| Option | Pros | Cons |
|---|---|---|
| New gas warm air unit | Reuses ducts | Still burns gas; no grant |
| Ducted air to air heat pump | Can reuse or adapt ducts; cools; £2,500 grant possible | Old ducts may need sealing, insulating or resizing |
| Wall-mounted air to air heat pumps | Simplest heat pump option | Units in each room; old ducts sealed off |
| Air to water heat pump with new radiators | Also does hot water; £7,500 grant | Most disruptive; new pipework throughout |
Things to check
- Old ducts can leak and lose heat. Ask the installer to inspect and test them.
- Older systems sometimes contain asbestos in ducts or flue parts. Have it checked before any work.
- Many warm air units also heat the hot water. Plan a replacement for that.
Questions
Can I replace warm air heating with a heat pump?
Yes. A ducted air to air heat pump can often reuse or adapt existing ducts, or you can switch to wall units or an air-to-water system with radiators.
Is warm air heating efficient?
Older gas warm air units are usually much less efficient than modern boilers, and much less efficient than a heat pump.
Sources
Checked 8 November 2026.