We had a new gas boiler (Buderus 500) fitted last year and it's worked very well. We HAVE had a history of leaks but they've all been found and repaired. The pressure never held at 1 bar, it always dropped to 0.5 but stayed steady there. We'd top it up every month or so it would, eventually, drop back to 0.5 but it took weeks to do it.
Recently, the pressure started dropping below 0.5 which immediately made us suspect a leak. Topping it up like normal didn't help as the pressure then dropped below 0.5 within day.
A detection company came round and spent three hours searching but, ultimately, could not say with 100% certainty that there was a leak. There was a patch of floor upstairs where it showed the heat spread being "slightly wider" than he would expect but he wasn't sure it was a leak. However, he did say that the expansion vessel was full of water and needed replacing.
So, we had a guy replace the expansion vessel and PRV but now the pressure stays at 1 bar for an hour before suddenly and rapidly dropping to ZERO! We've NEVER had it drop all the way down to zero before. The standing pressure always keeps it at 0.3
The plumber who replaced the expansion vessel is certain it's a leak because we have closed the two valves that isolate the boiler from the rest of the house and the pressure does not drop. As soon as we open the valves, the pressure drops slightly before rising as the water heats and then this rapid drop to zero occurs within two hours.
What is even stranger is that if we top it up again the pressure gauge rises incredibly quickly back to 1 bar. I mean, in like 1 second. Hardly any water gets added to the system. I would expect that if the pressure is at zero we'd have lost a LOT more water than that and it would take much longer to fill the system back up again.
Does anyone have ANY ideas at what this could be? It's sub-zero temperatures and we, essentially, have a totally broken system.
One other thing to mention - next to the PRV there is another valve with a small black cap (bit like a bicycle valve cap). Ever since the new boiler was installed that cap was tightly closed (no idea why) but I understand that it's meant to be slightly open. Several weeks ago (when I found this out) I loosened the cap but, unfortunately by too much, and dropped it behind the boiler. So, for a few days, the cap was off until I could finally get a replacement one. Not sure what damage (if any) that might have caused.....
Recently, the pressure started dropping below 0.5 which immediately made us suspect a leak. Topping it up like normal didn't help as the pressure then dropped below 0.5 within day.
A detection company came round and spent three hours searching but, ultimately, could not say with 100% certainty that there was a leak. There was a patch of floor upstairs where it showed the heat spread being "slightly wider" than he would expect but he wasn't sure it was a leak. However, he did say that the expansion vessel was full of water and needed replacing.
So, we had a guy replace the expansion vessel and PRV but now the pressure stays at 1 bar for an hour before suddenly and rapidly dropping to ZERO! We've NEVER had it drop all the way down to zero before. The standing pressure always keeps it at 0.3
The plumber who replaced the expansion vessel is certain it's a leak because we have closed the two valves that isolate the boiler from the rest of the house and the pressure does not drop. As soon as we open the valves, the pressure drops slightly before rising as the water heats and then this rapid drop to zero occurs within two hours.
What is even stranger is that if we top it up again the pressure gauge rises incredibly quickly back to 1 bar. I mean, in like 1 second. Hardly any water gets added to the system. I would expect that if the pressure is at zero we'd have lost a LOT more water than that and it would take much longer to fill the system back up again.
Does anyone have ANY ideas at what this could be? It's sub-zero temperatures and we, essentially, have a totally broken system.
One other thing to mention - next to the PRV there is another valve with a small black cap (bit like a bicycle valve cap). Ever since the new boiler was installed that cap was tightly closed (no idea why) but I understand that it's meant to be slightly open. Several weeks ago (when I found this out) I loosened the cap but, unfortunately by too much, and dropped it behind the boiler. So, for a few days, the cap was off until I could finally get a replacement one. Not sure what damage (if any) that might have caused.....
