COVID-19 update - Click Here

Guide to the Most Common Central Heating Problems (& Solutions)

It’s not unusual for central heating systems to get a little out of synch every now and then. Often, the problems aren’t very serious and just need a slight adjustment or a little tinker to solve. But sometimes the problems are more serious and calling in professional assistance is inevitable. We look at some of the most common problems your central heating unit is likely to experience, as well as their (relatively) simple solutions.

Cold patches on the radiators

First determine where the cold patches are. If the radiator is cold at the top, air has got into the system and you will need to bleed it out. Turn off the system, get a towel or bowl and place it under the radiator and find the bleed valve. Use your bleed key to open the valve just enough to let air hiss out. As the air escapes it will be replaced with water. You’ll know the job is done when water starts to drip from the valve. Close it and switch on the system again. Check the pressure and adjust if necessary.

If the radiator is cold at the bottom, it’s likely that there is some obstruction. This is usually scale, rust or sludge. An open-vented system is easy to fix, as you simply add sludge remover. If you have another system, however, the pipes will need to be physically flushed and that is best left to the professionals.

If the radiator is cold in the middle, it’s also likely to be blocked by rust or sludge. Except in this instance the problem is more severe than if the radiator is cold at the bottom only. Call a professional plumber to help you out.

Hot and cold radiators

If some radiators are hot and some are cold, it’s once again likely that the water flow is being obstructed. Make sure that the valves on both sides of cold radiators are open and open them further if necessary. If this doesn’t help, try descaling the system in much the same way you would de-sludge it.

Also consider where in the house the problem radiators are. If they’re upstairs you may need to add more water to the system. If they’re downstairs, your pump might not be working properly. If the pump is on the fritz, call a professional.

No heat or hot water

If your system appears to be producing no heat at all, try a few common sense solutions first. Check to see that the system is actually on and that the fuse hasn’t blown. If all the switches are in the right position and the fuse is fine, but the programmer is not showing anything then you could have a loose wire. Call an electrician.

  • Check the pilot light. If it’s out, you’ll need to relight it.
  • Check the gas supply. If gas doesn’t appear to be getting through, call your supplier.
  • Check the pump. If it isn’t working you can turn it off and try starting it manually. Wait until the pump is cold before restarting it. Remove the screw in the middle of the pump and turn the manual starter. Your instruction manual should give you a step-by-step process. If that doesn’t work, the pump might need to be flushed clean. Call a professional to do this.
  • Check the pressure. If it is too high, call a professional at once. If it is too low, fill up the system with water.
  • Check the condensate pipes on a condenser boiler, as they could be frozen. If they are frozen, thaw them with some hot (not boiling) water or a hot water bottle. Then insulate them to prevent the problem recurring.
  • Check the motorised valve. Use the manual lever to slide open the valve. If there is resistance you may have to call an engineer to help you fix the problem.

Disturbing noises

Hissing, banging and popping noises aren’t usual, so if your system has started to sing it could be a sign that something serious is wrong, such as overheating. Before you call in a professional, however, try descaling the boiler. This removes build-up that could cause overheating problems. Remember that you can only descale certain types of systems yourself. So double-check which system you have before you make the problem worse.

Also check the water level in the feed and expansion tank, as low levels can cause hissing and banging noises. If the level is low, it could be that it isn’t filling properly or a valve could be stuck or the water supply pipe could be frozen.

Whatever you do, don’t ignore the noises. Call for assistance sooner rather than later.

Leaking pipes

A leaky pipe joint might just need to be tightened. Do it a quarter turn at a time to ensure you don’t damage the joint or the pipe. If that doesn’t help, you might need to use some sealant. Bear in mind that this is temporary solution and the pipe will need to be replaced. Don’t wait too long.

A leaky pipe will need to be replaced ASAP. You can use sealant again as a temporary solution.

If your boiler is old, you might consider getting the whole thing replaced rather than carry out costly repairs. Find out about boiler grants available, as well as Green Deal Finance solutions.

If you do replace your boiler, make it a point to carry out regular maintenance and repairs and to have it serviced once a year. Not only will this prolong your boiler’s life, but it will also make your insurance company happy.