Biasi 24 Pressure Dropping

[ANDYSI]

I Have A Problem With A Biasi 24s 90e Combi Boiler Where The FILLING Pressure HAS DROPPED FROM ABOUT 1.8 BAR TO 1.2 BAR IN 2 WEEKS, BUT THE HEATED PRESSURE HAS REMAINED CONSTANT. IS IT MORE LIKELY TO BE A LEAK OR A FAULT WITH THE GAUGE AS I CANNOT UNDERSTAND WHY THE FILLING PRESSURE IS DROPPING BUT THE HEATED PRESSURE HASN'DROPPED AT ALL.

whats filling pressure and heated pressure ?

[ANDYSI]

filling pressure started at 1.8 bar now 1.2 bar. Heated presure 2.2 bar constantlyand hasn't changed even though filling pressure has dropped.

[spacethegas]

probably nothing to worry about. especially if it has been drained recently. the air in the system is just venting through aav. just top it up again to 1.5 bar. if it drops to 0.5 bar within a month you may have a problem.

[fuzzy]

dont fill to 1.8 bar thats too much. it may be over pressurised when hot, then it blws of at 3bar. better leave the cold pressure at 1bar, should rise to around 1.5 on heating.

if at these pressures it still drops check your expansion valve and pressure vessel

[ANDYSI]

Originally Posted by fuzzy

dont fill to 1.8 bar thats too much. it may be over pressurised when hot, then it blws of at 3bar. better leave the cold pressure at 1bar, should rise to around 1.5 on heating.

if at these pressures it still drops check your expansion valve and pressure vessel

I didn't fill it to 1.8 bar the central heating engineer I have the service contract with filled it to that and said it was OK as the pressure relief valve would vent any excess water.
I t's been 2 weeks since he was here and the cold pressure is maintaining at 1.2 bar and the hot pressure is now at 1.8 bar, but the hot water temp has been lowered to 50 degrees which I assume would have an effect on the hot pressure (lowering it due to lower heat expansion). It seems to be stable for now but I have had this problem for a while now and I fully expect it to drop of slower as the pressure gets lower. If anything changes I will post a reply.