Worcester Bosch 35cdi Loosing Pressure

[jurassic86]

Hello,

I have a Worcester Bosch 35cdi Combi boiler loosing pressure.
It all started when I took a few rads off to paint behind them, and reinstalled them.

I topped system up to 1.5bar, bled the rads upstairs after boiler was working for 1.5hrs and heating with piping hot.

The only reason I noticed was that the mrs was moaning because I put "Eco" mode on the boiler, and water would take longer to come through warm in the morning.

When I opened the panel cover, I noted the pressure was on the 0 (In the red) but the boiler didn't display any fault codes or anything, which I thought was strange.

So again I topped up the pressure and and run the boiler. The pressure increased to almost 2.1 bar, but then overnight when I come back down to check the pressure had reduced to 1.25bar.

After a little while longer the pressure has gone even further towards 1 bar. Still in the green but for how long?

I put a little plastic tray underneath the copper waste pipe outside, but only a trickle of water and I think that had something to do with the thunderstorm we had in the afternoon, so PRV seems ok.

Water does seem to trickle out of the plastic pipe which I believe is the condensation pipe next to it but would assume that is normal?

Anyone else have any suggestions as to what it could be?

Thanks
Jason

 

[petertheplumber12]

Check expansion vessel air pressure is 3/4-1bar with zero pressure in the system. Have you got too many rads for size of expansion vessel?

 

[jurassic86]

It was working fine before though, I only took rads off and painted behind them.
I thought if expansion vessel was broke the pressure would go sky high when it was running

 

[jurassic86]

Just an update guys,
bled all the rads and a tiny amount of air come out but not near enough to explain the loss off pressure.
I am just thinking- do some boilers just loose pressure until they hit 1 bar then just stay still.