The pressure guage is way down at the bottom, the pilot light is still on however when you turn it to hot water or radiators it doesn't kick in like it used to and as adove there is no heat or hot water.
Jus causer the pressure has dropped does not neccessarily mean a leak it could simply be air escapin through the automatic air vent, either way a pressure top up will be needed
1st thing there is a expansion vessel at the back of the boiler its big and red you need to check that there's air in it
By doing this u need to aquire a car tyre foot pump connect it to nozzle of the red expansion vessle when u look on the foot pump gauge and see that theres zero pressure check with the MI's first but im sure you need to pressurize it to 1bar with a drain point open
when u have achieved this and it stable for a few mins remove foot pump away from vessle ,close drain point,refilled system,vent and restart boiler all should be well.
if pressure is not stable and drops at every attempt chances are u have a split diagpram inside vessle thus replacement expansion vessle is rq'd easy option would be to install external vessel if unable to swap like for like good luck
I had a similar problem and found out that the multifuctional gas valve needed replacing as when i topped up the pressure the boiler worked for about 30 seconds and the flame went out but the pilot stayed alight. As for the leak, it was the air valve incorporated within the boiler.
When the pressure drop's below 0.6 bar, there is a safety device that stops the boiler firing up, you need to put more pressure into your heating system (only 1 bar is enough), as the pressure has dropped there must be a leak somewhere in your heating pipes.
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