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Boiler Breakdowns  

There are several causes of boiler breakdown that can be diagnosed and remedied by a layperson, without recourse to the expense of a heating engineer call-out.

Ensure that you have the appropriate copy of your boiler instruction/maintenance manual. This is your guide simply to be your first call when caring for your boiler and central heating system.

Basic troubleshooting guide. 

Checking the pressure in your system is an easy visual procedure. Note that some boiler models are not pressurised. Rather they have feed and expansion tanks in the roof space.

Your pressure gauge, should read between 1 and 1.2 bar. Symptom, less than 0.25 bar and your boiler needs to be brought back up to an effective operating pressure. This is a symptom of insufficient water in your system to hold the correct pressure. Remedy: Open the top-up valve and refill the system with water (see instructions below*).

Please note that frequent low-pressure readings indicate a pressure leak in the system.

Symptom: A constant 3 bar + might be because the top-up tap has been left open and the system has become over pressurised. Remedy: Turn of the top-up valve and see instructions below*.

*Refer your boiler manual for entries such as "re-pressurising, restoring pressure or water filling". Follow the instructions for your particular model exactly. When re-pressurising let the water flow slowly and carefully until you bring your boiler back to operating pressure. DO NOT OVERPRESSURISE! This will also cause the boiler to stop operating. 

Symptom: Radiators are not warm enough. Remedy; if the radiators are not getting hot enough ensure the thermostat on the boiler is set high enough for the weather conditions. It needs to be higher in the winter than the summer. The room thermostat does not adjust water temperature in the radiators.

Adjusting the regulator on the boiler can increase the temperature of the hot water. The temperature on ‘combi’ boilers needs to be turned up in the winter months in order to compensate for the colder incoming water from the mains.

Symptom: Boiler not working at all. Remedy: Check that the electrical fuses are working. No lights lit on the boiler indicates an electrical failure. Check the main house fuse board and if this ok, then replace the fuse in the plug or the switch spur feeding the boiler. The correct fuse rating is 3 amps.

Symptom: Boiler not working at all. Remedy: It is the room thermostat and programmer that initiate the boiler firing. Check your programmer controls to see if it is set correctly. Check the time settings and temperature. If you are in doubt or the boiler does not fire up on time reset the programmer to ‘constant’ to ensure the boiler is working.

Symptom: Boiler not working at all. Remedy: ‘Digistat’ wireless controllers are battery powered. Renew the battery when the warning light or icon indicates the batteries have run down. A continuous red light means that the connection between the transmitter, that’s the one with the temperature and flame in the window and the receiver, that’s the one with the marked buttons '1' and '2' is broken.

To remake this connection pull the battery compartment out so the display in the window disappears. Then press and hold buttons 1 and 2 together until the lights stop flashing. Hold the transmitter away from the receiver and push the battery home again. The receiver will flash and return to a normal mode. If you lose power for any reason you may need to repeat this resetting procedure.

We can help you to restore your boiler to working order if you call us with the following information to hand.

Ø      The make of your boiler and the model number. E.g. Vaillant TurboMax Plus. You can find this on the front of the boiler or just inside the control panel flap.

Ø      The fault code, if any, such ‘F20’ on the display. Many boilers self-diagnose in this way.

Ø      Work through the symptoms of your boiler problem one by one and try the remedies described here.

We are sure that you will find this trouble-shooting guide useful. We cannot take any responsibility for any adverse consequences from any actions that you may take without consulting with us first.