Start with heat output
Radiator output is listed in watts or BTUs per hour (1 watt is about 3.41 BTU/h). The output a room needs depends on its size, ceiling height, windows, outside walls and insulation. A heating engineer can calculate this room by room.
Manufacturers usually quote output at a standard temperature difference between the radiator and the room. If your system runs at a lower flow temperature – as many modern boilers and heat pumps are set up to do – the real output will be lower than the headline figure, so radiators may need to be larger.
Types of radiator
Each type suits different spaces:
| Type | Good for | Points to note |
|---|---|---|
| Single panel | Small rooms, tight spaces | Slim but lower output |
| Double panel / double convector | Most rooms | More heat from the same wall space |
| Column | Period homes, larger rooms | High output; cast iron is heavy |
| Vertical | Narrow walls, hallways, kitchens | Check output carefully |
| Heated towel rail | Bathrooms, en suites | Often lower output than a panel radiator |
Common radiator types
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Valves and controls
Thermostatic radiator valves (TRVs) let you set the temperature of each room. They're usually fitted to most radiators, with one radiator – often in the room with the main thermostat – left on a manual valve. Smart radiator valves add app control and scheduling.
What to tell your engineer
To get accurate quotes, share:
- The rooms and approximate sizes
- Where you'd like each radiator
- The styles you like, or models you've chosen
- Pipe centres of any radiators being replaced
- Whether rooms feel cold at the moment
- Any plans to extend or change the boiler
