Radiators not heating up? Check these first.
Most cold radiators have a simple cause. Here’s what each one usually means, what you can safely do yourself, and when to call us. We fix radiators and heating across Blackpool, Lytham St Annes, Fleetwood, Cleveleys, Poulton-le-Fylde, Kirkham and surrounding areas.
Stop and get help if
- You smell gas. Don’t switch anything on or off. Open the windows, leave the property and call the National Gas Emergency Service free on 0800 111 999.
- A radiator or valve is leaking and won’t stop. Turn the heating off and see what to do about a leak.
- The fix means taking the boiler’s cover off. Only a Gas Safe registered engineer should work inside a boiler.
What you see, and what it means
Cold at the top, warm at the bottom
There’s air in the radiator. With the heating off and the radiators cool, open the bleed valve with a radiator key until water comes out, then close it. Bleeding lowers the boiler pressure, so check it afterwards and top it up to between 1 and 1.5 bar. See boiler pressure.
Warm at the top, cold at the bottom
Usually sludge (rust and dirt from inside the pipes) settled in the bottom of the radiator. Bleeding won’t fix it. A power flush cleans the whole system out, and a magnetic filter by the boiler stops it building up again. If the water from the bleed valve is black, that’s sludge too.
One radiator stays stone cold
Check both valves are open: turn the thermostatic valve to its highest number, and check the valve at the other end (often under a plastic cap) hasn’t been closed. If it still won’t warm up, the pin inside the thermostatic valve may be stuck. We can free it or fit a new valve.
Radiators far from the boiler, or upstairs, stay cool
The system probably needs balancing, so the radiators nearest the boiler don’t take all the heat. We balance it in one visit. Sludge or a weak pump can cause it too, and we check for those.
All the radiators are cold, but you have hot water
Check the thermostat is turned up and the timer is set to heating on, then try the boiler checks. If that doesn’t fix it, a part inside the boiler (on a combi, usually the diverter valve) may be stuck. That’s a job for us.
Radiators are warm when the heating is off
A valve is stuck open, usually the diverter valve on a combi or the motorised valve on a system boiler. Call us and we’ll replace it.
How we can help
- Bleeding and balancing the whole system.
- New radiator valves and thermostatic radiator valves.
- Power flushing to clear sludge, and magnetic filters to keep it clear.
- Moving or adding radiators.
- New and replacement radiators: single from £260, double from £320. See typical prices.
- A 12-month guarantee on our workmanship.
Common questions
How often should I bleed my radiators?
Only when one is cold at the top. If you have to bleed the same radiator every few weeks, air is getting into the system somewhere. Ask us to look.
Why has my boiler pressure dropped after bleeding?
Bleeding lets a little water out, so the pressure falls. Top it up once. If it keeps dropping, see pressure keeps dropping.
Will a power flush fix my cold radiators?
If they’re cold at the bottom or in the middle, usually yes. It won’t fix air, a stuck valve or a fault in the boiler, so we check what’s causing it first.
Can I fit a bigger radiator?
Yes. We check the size against the room so it heats properly, and fit it on the existing pipes where we can.
Send an enquiry
Tell us what you need and we'll get back to you. You can also call 07498 614173 or email enquiries@networknw.com.
Smell gas? Don't use this form. Call the National Gas Emergency Service free on 0800 111 999, 24 hours a day.