boiler pressure keeps dropping .have changed pressure switch and p.r.v valve. exspansion tank seems ok . cant find any leeks any ideas.

roly, August 2008

I had a similar problem on a job last year.Took me ages to find a cure.Eventually I fitted a new expansion vessel and I haven`t been called back in over 8 months.
It`s a strange fault,because it appears to be a leak yet there is no sign of water.I can only think that the diaphragm in the expansion vessel is perforated and slowly lets water through which mimics a loss of pressure.

If the vessel is awkward to get at,just fit a new round vessel somewhere else on the system,it`ll do the same job.

Gasman, August 2008

thanks for your help had floorboards up even engineer is puzzld no leaks.

roly, August 2008

isolate the flow and return on boiler for 24 hours..dont use boiler

if the pressure drops its a boiler problem........sounds like a system leak to me they are not always in your face could be under floor boards etc

corgi bloke, August 2008

ferroli combi 901 top up cup of water 3 times a day if heating is put on it will run ok till turn off the pressure will dropp heating engineer checked air pressure ok still no sighns of leeks on syst

roly, August 2008

Questions, Questions Questions.

what have you done to check the expansion tank? how much does the pressure drop by and over what time period? do you bleed your rads alot? Is it a combi? And have you tried putting leak sealant in the system?

LTGF, August 2008