vokera boiler losing pressure

[stimms212]

i have a vokera mynute 14e boiler and over the past 6 months i've had a problem with it dropping pressure.so i changed the pressure release valve, still the same, then changed the expansion vessel which i pumped up with a bicycle pump to about 0.7 bar,now although it runs perfectly with hot water and hot radiators, everytime i top it up from the filling loop it always drops back to half a bar.i've also checked for leaks over the house and no obvious signs of any leaks.please could someone give me any advice on why the pressure is on half a bar all the time and what my next step should be.thanks.

 

[glasgowgas]

make sure the flow and return 1/4 turn valves underneath the boiler are fully opened. then take pressure up to 1 bar.

if when system gauge is 0 does it rise when you open filling loop?if it does then we know water is flowing through your filling loop.

could be your water pressure is down, only giving 0.7 bar inlet.

or check valve choked

 

[stimms212]

thanks glasgowgas. the system gauge does rise to about 1 1/2 bar then gradually drops to 1/2 bar after filling.gave prv a blast to clear out any dirt but still same problem.do you think the expansion vessel needs more pressure,according to the manual it needs between 0.4 to 0.8 bar. its losing pressure somewhere but i don't know where.everything seems fine apart from it staying at 1/2 a bar and is it safe like that.

 

[glasgowgas]

thanks glasgowgas. the system gauge does rise to about 1 1/2 bar then gradually drops to 1/2 bar after filling.gave prv a blast to clear out any dirt but still same problem.do you think the expansion vessel needs more pressure,according to the manual it needs between 0.4 to 0.8 bar. its losing pressure somewhere but i don't know where.everything seems fine apart from it staying at 1/2 a bar and is it safe like that.

what you could do is fill boiler to 2 bar.
close 1/4 turn flow and return valves underneath boiler

if pressure holds 2 bar = leak in system
if pressure drops = leak in boiler (prv poss)

obviously don`t run boiler while doing this test!