Low Boiler Pressure

[suewood59]

hi i wondered if anybody can give me any clue as to why  my boilers pressure falls flat when i turn the heating of. iv had a new pressure releif valve fitted ,the pressure vessals ok. iv just had a sevice on it and everythings ok with the boiler yet everyday i have to repressurize the boiler  its really getting to me everyone says we must have a leak but we cant find one short of taking all the laminated flooring up but surely we have some sign of a leak thanks in advance if anyone has any advice sue

 

[steptoe]

what sort of boiler is it?

combi or system?

 

[batty]

Sounds like you definitely have a leak somewhere is it wooden floors or screed?

 

[SLIPSHOD & SLAPDASH]

The pressure will drop when its cold but not to nothing. What pressure are you putting in it at cold and what is it at hot ?

It sounds like the pressure vessel needs pumping up , this is a large round metal container  (sometimes red) in the back of the boiler ,  That's done by a Schrader valve thats the same as you find on a car tyre & its done with a car tyre pump. Check the Manuel for the correct pressure

If its not that you have a leak, hard luck with the floors but try a bit of toilet paper round each rad pipe under the valves, this shows up  very small leaks

 

[Sidecutter]

Yes I agree with the above I had a presure vessel lose presure and spent weeks looking for leaks and constantly topping the pressure up until somebody told me about checking the pressure vessel

 

[Andy™]

if its the expansion tank, then the boiler will be blowing off regularly. is there any water at the blow off pipe at any time? if not, then its probably a leak

 

[Sharpend]

It could be the diaphragm in the vessel that is leaking and not holding pressure, had this on a valiant boiler, new vessel and problem solved.