Boiler is a British Gas (Bosch) 537i which is about 10 years old. We have 14 radiators. There is an auto bypass valve fitted.
The pressure gauge reduces from 1 bar to 0 over about a day. During this time water is released from the PRV discharge pipe, but only 100 to 200ml.
It then takes only about 10 or 15 seconds to repressurise using the filling screw on the boiler turned about 1/4 turn.
During all this time, the pressure gauge reading does not increase abnormally other than a 1/4 bar or so as the temperature rises. It does not get anywhere near 3 bar. I have a CCTV camera pointed at it at the moment so I can check what the gauge has been doing.
If I deliberately fill the system up to and indicated 3 bar on the gauge then the PRV releases and a lot of water comes out until it closes again.
I think the expansion vessel is ok. It had plenty of air in it. I emptied it and plenty of air came out. Some water also came out but only about 50ml or so. I then repressurised it up to 0.7 bar with the system drained and the drain tap open. If this was faulty I'd expect the pressure gauge to rise?
We had someone in to replace the PRV (a pain as the whole hydraulic block needed to come out), but that has made no difference.
Any ideas what could be causing the PRV to let by, but not register high pressure on the gauge, and only let out a small amount of water?
Cheers.
The pressure gauge reduces from 1 bar to 0 over about a day. During this time water is released from the PRV discharge pipe, but only 100 to 200ml.
It then takes only about 10 or 15 seconds to repressurise using the filling screw on the boiler turned about 1/4 turn.
During all this time, the pressure gauge reading does not increase abnormally other than a 1/4 bar or so as the temperature rises. It does not get anywhere near 3 bar. I have a CCTV camera pointed at it at the moment so I can check what the gauge has been doing.
If I deliberately fill the system up to and indicated 3 bar on the gauge then the PRV releases and a lot of water comes out until it closes again.
I think the expansion vessel is ok. It had plenty of air in it. I emptied it and plenty of air came out. Some water also came out but only about 50ml or so. I then repressurised it up to 0.7 bar with the system drained and the drain tap open. If this was faulty I'd expect the pressure gauge to rise?
We had someone in to replace the PRV (a pain as the whole hydraulic block needed to come out), but that has made no difference.
Any ideas what could be causing the PRV to let by, but not register high pressure on the gauge, and only let out a small amount of water?
Cheers.
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