Common central heating problems

If your home is heated by oil-fired central heating, here are a few tips that may help you.

Complete loss of heating / no hot water

To isolate your heating problem, check the following:

  1. Is the power supply on at the mains? If not then contact your electrical supplier.
  2. Is the boiler gas supply fine? When the gas stopcock is on but no gas is coming through, you have a gas supply problem and need to call you gas supplier. In the case of oil boilers, check there's enough oil in the tank by reading the gauge.
  3. Pilot light igniting? If your boiler's pilot light won't ignite, you either have a gas supply problem (contact your gas supplier) or please call us to arrange for our Gas Contractor to attend and repair the problem.
  4. Is the central heating programmer in the ‘on’ position and thermostats are turned up high enough?
  5. Central heating pressure correct? Check it's set to the manufacturer's instructions (generally 1 bar). If it is, either you have a gas supply problem (contact your gas supplier) or please call us to arrange for our Gas Contractor to attend and repair the problem.

Partial loss of heating

  1. First, turn off the central heating at the main controls.
  2. You will need to bleed your radiator so that the trapped air can be released. The air release point or valve is located on the side of each radiator. Open it with a radiator key (available from most DIY stores).
  3. There will be a hissing sound as the air escapes.
  4. As soon as the water begins to flow, close the air vent.
  5. Switch on your central heating again.
  6. If your radiator is cold at the bottom, this indicates a build up of rust and sludge. Please call us to arrange for our Gas Contractor to attend and repair the problem.

Noisy boiler

Hissing or banging noises from your boiler or heating pipes are caused by the following:

Scale in the heating system

The build up of scale can be treated with a chemical descaler. This involves shutting down the system, adding the product, and leaving it to work for a few days. The system then needs to be drained, flushed through, and refilled. This can cause ‘hot spots’, which produce loud bangs from steam bubbles. This can be treated by adding a chemical descaler to the feed and expansion tank. The system then needs to be drained, flushed through, and refilled. Please call us to arrange for our Gas Contractor to attend and repair the problem.

Lack of water or pressure in the central heating system

You will need to double check that the mains water is on. If it is, please call us to arrange for our Gas Contractor to attend and repair the problem.

Another cause could be that you have burst or frozen pipes. If the problem is a lack of water pressure, the pressure indicator on your central heating boiler will usually indicate it needs to be increased.

Boiler failure

  1. If your boiler won't turn on, the problem could be with its pilot light. Check whether the gas stopcock is open. If no, turning it on will solve the problem by restoring gas supply. If yes, please call us to arrange for our Gas Contractor to attend and repair the problem.
  2. When there's no gas coming through the gas stopcock, you have a gas supply problem and need to call your gas supplier.
  3. Check the pressure is set to the manufacturer's instructions (generally 1 bar). If the central heating pressure is correct, either you have a gas supply problem (contact your gas supplier) or you'll need to get an engineer to visit. Please call us to arrange for our Gas Contractor to attend and repair the problem.
  4. If your boiler only works (provides hot water) when the central heating is on, please call us to arrange for our Gas Contractor to attend and repair the problem.

Faulty boiler controls

  1. Thermostats – check the thermostat. Most thermostats also include good energy-saving controls to warm your house when you need it and turn the heat down when you don’t. This can cut your heating bills by 10-20%.
  2. Programmers & Time Switches – these are time-clock driven. Check that the clock dial isn’t stuck or the program on/off timing will be wrong. The hot water and heating are controllable via the timer switches found on your boiler.
  3. Electronic programmers – check that the LCD display is working.
  4. Radiator valve - if you have a thermostatic radiator valve on your radiator, adjust it the heat you need. If no change occurs after you’ve adjusted the settings, you have a fault with your radiator valve.
  5. If any of the above are not working then please call us to arrange for our Gas Contractor to attend and repair the problem.

Cold radiator

For a cold radiator problem, try the following checklist:

  1. Boiler gas supply on? When the gas stopcock is on but no gas is coming through, you have a gas supply problem and need to call your gas supplier. In the case of oil boilers check there's enough oil in the tank by reading the gauge.
  2. Pilot light igniting? If your boiler's pilot light won't ignite, you either have a gas supply problem (contact your gas supplier) or you'll need to call in a Gas Safe engineer for a repair.
  3. Central heating programmer in the ‘on’ position and thermostats are turned up high enough?
  4. Build-up of rust or sludge? A cold patch at the bottom of the radiator means you need to flush it out. If one radiator isn't warming up, solving the problem depends on where it's located:

Upstairs radiator

This is an indication that the feed and expansion tank in your loft has run dry. Call us to arrange for our Gas Contractor to attend and repair the problem.

Downstairs radiator

This is an indication that the pump is faulty.  Please call us to arrange for our Gas Contractor to attend and repair the problem.

When radiators are cooler in one area of the house

When the radiators closest to the boiler are hotter than those further away, it means you have a 'balancing' problem.  Please call us to arrange for our Gas Contractor to attend and repair the problem.

Smell gas? Call 0800 111 999.