Fix a cold radiator#
If a radiator is too cold to the touch and not heating a room enough, you or your installer may have turned up the boiler thermostat or increased the pump speed to compensate. This isn’t as efficient or effective as finding out why the radiator is cold in the first place.
First check the TRV isn’t broken or turned right down.
If the radiator is completely cold, there could be a stuck valve somewhere in the system.
If the radiator is cold at the top, you may need to bleed the air from the radiator.
If the radiator is cold somewhere else, you may have sludge in it. A powerflush should sort it, and you may need to add a magnetic filter to the system.
Sometimes the problem is a faulty pump not getting enough hot water into the radiator.
Sometimes the radiator isn’t being supplied with sufficient hot water because other radiators are getting most of the heat. Systems are meant to be balanced by checking that every radiator has the same difference between the water temperature going in and coming out, but few installers bother checking this, especially if the radiators are only coming down to decorate behind them. If you are patient and methodical, checking the balance is something you can do yourself, but you probably want to get a professional in to do the actual balancing because it involves moving valve positions. They’re best placed to fix the valve if it starts to leak. Radiator valves that keep a system in balance automatically are starting to come on the market but this seems a relatively expensive way to address what is an occasional re-balancing need.