Diagnose cold radiators

When it's a bit chilly the last thing you want is to come home to a cold house. Make sure that you stay toasty with our top tips on troubleshooting cold radiators.

All radiators are cold

It might sound obvious, but first check that you have turned your heating on. If it's on and your radiators are still cold then your heating system could be full of sludge, stopping the circulation of hot water.

If you have an open vented heating system you should be able to solve this problem by cleaning your system:

  1. Buy a heating system sludge remover at your local DIY store.
  2. Add the liquid to the feed and expansion tank.
  3. After a few days you will need to empty and refill the system. Non-open vent systems require you to flush through the radiators with a hosepipe.

Cleaning your heating system can be a big job, so if in doubt get a professional plumber out.

One radiator stays cool

If one radiator stays cold:

  1. Check that both valves on the sides of the radiator are open.
  2. If the valves are open but the radiator is still cold then the valves may be blocked by limescale.
  3. If this is the case, the radiator may need to be flushed out.

Cold bottom section

This problem also tends to be caused by sludge in the system. Again, add some heating system sludge remover and give the whole system a refill.

Cold top section

If your radiator is hot at the bottom and cool at the top then it's most likely that air is trapped in the system. Bleed your radiators and the problem should be sorted.

Cold radiators upstairs

Cold radiators located in the upstairs section of your home usually mean that the feed and expansion cistern is empty.

  1. The cistern is usually found in the loft.
  2. Refill the cistern so that there is just enough water to float the ballcock.
  3. Don't fill it up completely, as there must be enough room for the water to expand.

With a full cistern the upstairs radiators should start heating, but it is a good idea to get a professional plumber in to work out why the cistern ran dry in the first place.

Cold radiators downstairs

If your downstairs radiators are failing to heat up then there's a good chance that your pump is broken or on its way out. If you're DIY mad you may want to read up on how to tackle the problem yourself, but if in doubt then call on the skills of an expert plumber ASAP.

Remember, cold radiators could lead to frozen or burst pipes in winter, so they need to be tackled quickly.

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