Combi boiler losing pressure

[terryplumb]

If it was an issue ,you would have known shortly after they were installed and central heating used. If the ev couldnt cope with the additional volume of water and corresponding expansion ,your system pressure would increase to a point where the prv would operate to release water out the system. You would then probably have had to top up regularly ,was that so ?

 

[Gazmcc84]

Not that I noticed and it was done over 3 years ago.

I have reduced the boiler pressure to 0 and started to reinflate the expansion vessel, looking at the boiler gauge this has now risen to 0.5 bar, does this mean air is getting across to the water side and the ev is dead?

 

[terryplumb]

No ,it means you are adding pressure to a sealed system that should be de pressurised before you start ,and during , pumping air into the ev.

 

[Gazmcc84]

Ah ok I think I have this straight in my head now, basically there is too much water in the system as I understand it, So I need to drain water off to allow the water pressure guage to return to 0 then check the ev air pressure again to make sure it remains at around 15 psi or .8 bar

 

[terryplumb]

Not quite got it gaz ,as well as letting water out you need to allow the boiler /system to vent ,so you are not pumping the ev against a sealed system. Leaving a drain cock open for instance .

 

[Gazmcc84]

Ok. I'll try again, I noticed now that the pressure has returned to zero after draining water off that air has come out of the auto air valve and the pressure in the ev is back to zero, I take it that that will sort itself out and air will stop escaping when I re inflate the ev with a drain cock open?

 

[terryplumb]

Once the ev is charged correctly ,close drain cock ,fill system to 1 bar ,bleed air from all rads ,aav in boiler should vent automatically , re check system pressure / top up to 1 bar. And run ch .monitor pressure gauge. If all good ,happy days !!!

 

[Gazmcc84]

Fingers crossed that has sorted it. Very grateful Terry for your help .didn't have a clue otherwise, looking good so far as the fluctuation of pressure from cold to hot is around .2 bar .Before was around 1.5 bar causing the prv to kick in. Just waiting for cool down and hopefully pressure will be back around 1 bar

 

[dilalio]

But do this when water side of EV is unpressurised and able to push water out.

I would have said open to atmosphere but that can be misconstrued.