Central Heating Will Not Switch On

If your boiler is failing to warm up your home through central heating, then it is probably not the case that this problem can be resolved by you alone. It is very dangerous for the unqualified to try their semi-educated hand at fixing gas appliances (it is against the law). Most central heating insurance will always send very qualified engineers in the event your central heating breaks down.

Central heating will not turn on

First, have a look at your thermostat. The problem may be as rectifiable as having been off the entire time.

If the thermostat is set too low, the central heating will not activate until the temperature of the room is below the thermostat’s set temperature. Dial-up the thermostat to its topmost setting and see if this solves the issue.

Second, have a feel of your radiators. Are they all cold? If at least a single radiator feels lukewarm or the lower half of one or a few is partially warm, it may be worthwhile to look at some guides at fixing your radiators.

It may be necessary to bleed your radiator(s).

Third, inspect the water pressure. Boilers for domestic use usually indicate the water pressure with one bar.

On a dial, it should be just above one bar but in no way at either extreme. Boiler pressure should not fluctuate daily — it should be constant. Without pressure, a boiler is unable to do what it needs to. While you can refill a tank with water manually, constant pressure loss comes from many different sources and is worth talking to a qualified engineer about, since it could indicate a serious problem with your pipes and appliances.

Next, ask yourself if you are reading this in winter. Are your pipes frozen or close to zero degrees celsius? A boiler will not work properly if the pipe at its rear is near to freezing. You can find out about how to go about safely defrosting frozen pipes online.

You may be able to thaw frozen condensate pipes without too much trouble if you follow the steps below. First of all, how to thaw the condensate pipe.

  • Use hot water (not boiling) and pour over the end of the pipe where it is frozen using a vessel such as a jug that does not conduct heat (i.e. not metal).
  • Wrap a hot water bottle or heat wrap around the condensate pipe.
  • The pipe will begin to warm and you should able to soft reset your boiler by holding in the reset button for at least fifteen seconds. Wait for the sound of your boiler refiring.

A few words of warning about this process: You should never attempt to thaw a condensate pipe above your waist, or disconnect the condensate pipe to do so. You should also never attempt to access the condensate pipe or any other pipework inside the boiler. Also, watch out for thawed ice on the ground that will form from the water you have poured.

If the condensate pipe is not your trouble, your central heating could be failing because you have programmed the timer to come on at set times. To see if this is the case, refer to the manufacturer’s manual or online notes for your make and model to see if you have a timer programmed without your awareness.

However, to make life easier (not!) your timer can also reset if you’re boiler has recently lost power in a power outage or the fuse box circuit trips. A very good, simple fix is to turn your boiler off and on again, at the gas switch and electronic panel. Wait for at least one minute before restoring power. Sometimes all you need is a ‘soft’ reset.

Not a fan of boiler fan replacement?

There are many other reasons why your central heating is not working or your boiler not firing up such as a broken fan or loose electrical wiring. The boiler fan will start up before anything else and is essential.

Each boiler is fitted with a flue – a large white pipe. There will either be vertical flue (going through a roof) or a horizontal flue (going through a wall). This is what takes toxic gases away from your property.

However, the flue is not capable of transporting all the gases from the boiler on its own, it’s simply a place for them to escape. This is why a boiler fan exists. The fan creates a small draught that will push flue gases up and out of the flue.

The printed circuit board (PCB) needs to ‘chat’ with a running circuit board before anything begins. If it doesn’t recognise the fan is running, it will lock out and display a fault code related to an air fault, or fan problem.

Boiler fan replacement costs vary because no two boiler fans are the same price. As a guideline, expect to pay in the region of £225-275 including parts and installation.

There are two types of faults to look out for:

  • Faults relating directly to the fan’s operation
  • Air faults, that hinder the fan’s operation

The fan speed could be too low, have loose wiring/connections, have damaged wiring and connections or the entire unit could be faulty.

If your boiler is 5+ years old, there’s a small chance the boiler’s fan has failed completely. Find out more about boiler cover here.