Combi boiler pressure falls to zero when heating is put on All aspects of plumbing questions and answers, help, tips and information

[monkay]

Hi,
I just went to turn the heating on and it is not working. The pressure is reading just under 0.5 bar and when I put the heating on the pressure falls to 0.

I've got the instruction manual but it doesn't say how to increase pressure only how to decrease it.

Could someone give some help which tap I need to turn to increase pressure please?

There only seems to be a tap on the DHW inlet but I have turned and turned this and nothing happens.

[frank pope]

Check under the boiler and locate the cold water supply pipe (15mm), there will be a valve located in the pipe (flexi-hose) or on the boiler nearby. Open the inlet and you will hear water entering the system. Monitor the guage to 1 to 1.5 bar. You may need to bleed the radiators after repressurising (heating off) as there may be air in the system causing a loss of pressure.