Alpha CD32C combi boiler

[JRobG]

THE RV is passing on my combi boiler, This has been installed for 5 years. & this is not the first time this has happened, the pressure is at 3 bar, therefore the RV is lifting.
I believe this to be attributed to the expansion bottle losing its set pressure, red bottle at the back of the wall mounted unit.
What is this supposed to pressurise to?
The eng that used to repair this used a car foot pump to pressurise the bottle.

 

[45yearsagasman]

De pressurise the system and open the PRV and pump the exp vessel to approx .75-1 bar. You may also have to replace the PRV if it fails to close.
Use of a foot pump is perfectly OK. If water comes out of the schrader valve then the vessel is kaput.

 

[JRobG]

Cheers,
45yearsagasman
I bought a new foot pump, so I had some faith in the pressure gauge, I followed the instruction you gave. The expansion bottle did take some pressurising, I thought is wasn’t going to show on the foot pump gauge, but did eventfully, re seated the PRV, tested to see if the boiler pressure changed overnight, It lost a little pressure but so far so good PRV not lifting, boiler gauge pressure approx 1.25 bar.
I haven’t tested with radiators circulating as yet.