Match what you notice
- One radiator stays cold while the others warm up
- If the room is still cold, we check whether the radiator valve is opening and whether water can flow through the radiator. Mention if it started after the radiator was removed, moved or refitted.
- The top stays cold but the bottom warms up
- Trapped air can prevent the top from warming. Tell us if you hear gurgling or if the cold area keeps returning.
- A broad area at the bottom stays cold
- The bottom can be cooler during normal operation. A persistent cold patch can also point to restricted flow or deposits. We check the pattern and the valves before suggesting work.
- Several radiators are affected
- Tell us if the radiators on one floor or at one end of the property are affected. The pattern can point to an issue shared by more than one radiator.
What the two radiator valves do
The numbered thermostatic radiator valve, or TRV, responds to the temperature around its head and controls water flow through the radiator. If the room is already warm, a radiator cooling down can be normal. A capped lockshield valve is often used to balance flow. We check how the valves and the radiator work together.
What to send before a visit
Share your postcode, the room affected and when the problem started. A photo of the full radiator and one of each valve can help. Tell us if there is water at a valve or under the radiator. Leave capped valves and pipe connections in place.
Read what to do if the radiator is leaking