Worcester Bosch 35cdi Loosing Pressure

[jparker86]

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

 

[Ollieg]

Could of been air. Tape a plastic bag over the prv pipe to see ifs leaking.
Pressure rising when heating goes on is normal within limits. If it goes to 2.5 bar I would get it checked by a GSR engineer. How did you drain it?

 

[jam1979]

check theres no visable signs on your rad glands of leakage and also theres no puddles under ur boiler ruling out cracked heat ex could ur pressure gage be faulty

 

[jparker86]

Hello Guys,
Thanks for all your replies.
I have opened the cover off, checked the expansion vessel and air come out when I give it a press.
No leaks at all, I have put tissue paper under the boiler and its as dry as my hair on a summers afternoon.
Each time I fill the system its hovering around the 44deg mark, maybe i should only fill it when its stone cold.
The other thing to note is when I filled it up the pressure went sky high (but not in the red - 2.5bar) and I took out 4-5 pints of water from one of the rads to drop the pressure down back to 1.5bar.
J

 

[Crinkmeister]

I'd put money on one of the rads you moved having a teeny tiny leak. And you shouldn't be taking covers off boilers and p**ing about inside unless you are GSR or Mr Croppie will be very cross with you!!

 

[jparker86]

I'd put money on one of the rads you moved having a teeny tiny leak. And you shouldn't be taking covers off boilers and p**ing about inside unless you are GSR or Mr Croppie will be very cross with you!!

Well I just went around and checked and what do you know, one of the rads had a tiny drip (one drop every couple of seconds).
Do you think this would be enough to explain half a bar a day in pressure drop?

 

[Ollieg]

Yes!

That's the problem.

 

[Crinkmeister]

Well I just went around and checked and what do you know, one of the rads had a tiny drip (one drop every couple of seconds).
Do you think this would be enough to explain half a bar a day in pressure drop?

I had a similar problem but with a much slower leak. It took about a week to lose 1 bar and the leak was hidden by the plastic pipe covers I had fitted, so no visible sign until I took all the covers off and found one with a telltale blue-green deposit on the copper and moisture inside the cover. Glad you found it so quickly - mine took a couple of months to find.

 

[vern]

Croppie? you sleeping?

 

[jparker86]

I had a similar problem but with a much slower leak. It took about a week to lose 1 bar and the leak was hidden by the plastic pipe covers I had fitted, so no visible sign until I took all the covers off and found one with a telltale blue-green deposit on the copper and moisture inside the cover. Glad you found it so quickly - mine took a couple of months to find.

Tell you what was ironic, the only reason I found it was because I was looking for my radiator bleed key and thought maybe i left it near one of the rads, and there I seen some tiny water drops on the skirting board. Who knows where all the water has gone to in the meantime but I am just just glad I found it.
Its been 3-4 hours now and no drop in pressure so fingers crossed.
J

 

[jam1979]

tie a piece of tissue round each rad valve and leave for a bit to see if that's the only leaking rad