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roachp · Mar 9, 2016, 07:04 AM

The pressure gauge on my combi boiler dropped to zero.An engineer stated that there was no external discharge of water and diagnosed a boiler fault (PRV).I was told it was OK to keep using the filling loop till the parts arrived.Two days later I had water coming through my ceiling from a weeping T Joint.Was his diagnosis and subsequent advice the correct way to go about rectifying this fault?

massplumber2008 · Mar 10, 2016, 08:44 AM

Hard to say from here, of course. It could be that you over-pressurized the system and found a faulty joint, or it could be that you found the actual leak that started the problem to begin with. Either way, as I see it, the engineer gave you reasonable advice and I see no fault on his/her part. Repair the leak, install a new boiler fill valve and you should be all set!

Mark

roachp · Mar 10, 2016, 09:49 AM

Originally Posted by massplumber2008

Hard to say from here, of course. It could be that you over-pressurized the system and found a faulty joint, or it could be that you found the actual leak that started the problem to begin with. Either way, as I see it, the engineer gave you reasonable advice and I see no fault on his/her part. Repair the leak, install a new boiler fill valve and you should be all set!

Mark

Thanks for your response Mark.I thought that only a leak from the system would cause the gauge to drop.Could a faulty fill valve result in a continual loss of pressure?If the fill valve was at fault would the boiler still work after using the filling loop?The leak has been repaired and now the boiler works fine without any replacement parts being needed which would indicate that a leak was the problem and nothing to do with the boiler.It would also appear that the advice to keep using the filling loop resulted in me feeding the undetected leak until the water presented itself through my ceiling.

massplumber2008 · Mar 10, 2016, 02:06 PM

Yes, a faulty fill valve could result in a loss of pressure over time if there was a leak of some kind... as it appears there was in this case. Here, I suspect that a small leak developed (this tee leak is my guess) and the system went down to 0 pressure, and the fill valve was faulty so it failed to repressurize the system which would have eventually led you to the leak. Since you refilled the system, it made the leak obvious.

You should be all set now...

roachp · Mar 10, 2016, 10:44 PM

Originally Posted by massplumber2008

Yes, a faulty fill valve could result in a loss of pressure over time if there was a leak of some kind... as it appears there was in this case. Here, I suspect that a small leak developed (this tee leak is my guess) and the system went down to 0 pressure, and the fill valve was faulty so it failed to repressurize the system which would have eventually led you to the leak. Since you refilled the system, it made the leak obvious.

You should be all set now...

Thank you once again for your reply.I can only once again state that the fill valve has not needed replacing nor was the pipe to the exterior wet therefore it could not be at fault.With no obvious leaks from the rads the only other option could have been a leak in unseen pipe work.Hindsight is a wonderful thing and I would have much preferred to have been told this in order to lift a few boards and try to find the leak rather than waiting for the leak to become obvious after days of feeding it via the loop.

Mike45plus · Mar 11, 2016, 04:56 AM

Originally Posted by roachp

Thank you once again for your reply.I can only once again state that the fill valve has not needed replacing nor was the pipe to the exterior wet therefore it could not be at fault.With no obvious leaks from the rads the only other option could have been a leak in unseen pipe work.Hindsight is a wonderful thing and I would have much preferred to have been told this in order to lift a few boards and try to find the leak rather than waiting for the leak to become obvious after days of feeding it via the loop.

Roach,
Any experienced heating professional or mechanical engineer should have recommended a diagnostic sequence that would include a pressure test of the boiler and piping once there was a severe pressure drop in the heating system. A pressure test is easy & effective, and in many cases can prove the integrity of gauges, valves, joints, components, vessels, and piping separately in an orderly fashion to isolate the source of the leak...

roachp · Mar 11, 2016, 10:19 AM

Originally Posted by Mike45plus

Roach,
Any experienced heating professional or mechanical engineer should have recommended a diagnostic sequence that would include a pressure test of the boiler and piping once there was a severe pressure drop in the heating system. A pressure test is easy & effective, and in many cases can prove the integrity of gauges, valves, joints, components, vessels, and piping separately in an orderly fashion to isolate the source of the leak...

Thank you for explaining that.It clears everything up.