Hello,
I have an old Vaillant combi - not sure of the exact model or year, but I believe it's an aquaPLUS installed sometime early 2000s - that is puzzling me. Three times now it has given me the "low pressure" F.22 fault code.
October: First time; called an engineer who came out, added water via the integrated filling loop, and said he couldn't see any obvious signs of leak. Nothing inside the boiler casing was wet nor were any of the pipes leading to/from the boiler and radiators.
December: Second time; I couldn't (and still can't) figure out which one is the filling loop or how to use it, so I simply turned the boiler off and on again. This worked. Fault code no longer shown, heating and hot water back.
Today: Did it again. I pressed the reset button, and, again, the fault has cleared.
The pressure, ever since I started keeping an eye on it after the engineer came, has always been 0.3/0.4bar when the heating is off and 1.4-1.6bar when on.
I believe that the cold pressure is supposed to be around 1bar and that the pressure shouldn't rise more than 1bar when on. Additionally, each time the boiler has given the fault it's been moments after I've tried to run the hot water while the heating is off. But running the hot water when the heating is on doesn't make the pressure drop (yes, I've sat and watched it to check). And it also doesn't happen every time I run the hot water while the heating is off, although I must say I'm pretty paranoid about it now.
So it seems to me something is going on - possibly expansion vessel or pressure relief valve. I've read that the typical sign of expansion vessel trouble is the pressure going very high when the heating is on, but mine's not doing that - although I suppose if it was 1-1.5 cold and still rising by the ~1bar it would be?
What troubleshooting steps should I follow to try to narrow this problem down before I call in the engineer? I want to have a clearer idea of what might be happening.
Thanks so much for your help
I have an old Vaillant combi - not sure of the exact model or year, but I believe it's an aquaPLUS installed sometime early 2000s - that is puzzling me. Three times now it has given me the "low pressure" F.22 fault code.
October: First time; called an engineer who came out, added water via the integrated filling loop, and said he couldn't see any obvious signs of leak. Nothing inside the boiler casing was wet nor were any of the pipes leading to/from the boiler and radiators.
December: Second time; I couldn't (and still can't) figure out which one is the filling loop or how to use it, so I simply turned the boiler off and on again. This worked. Fault code no longer shown, heating and hot water back.
Today: Did it again. I pressed the reset button, and, again, the fault has cleared.
The pressure, ever since I started keeping an eye on it after the engineer came, has always been 0.3/0.4bar when the heating is off and 1.4-1.6bar when on.
I believe that the cold pressure is supposed to be around 1bar and that the pressure shouldn't rise more than 1bar when on. Additionally, each time the boiler has given the fault it's been moments after I've tried to run the hot water while the heating is off. But running the hot water when the heating is on doesn't make the pressure drop (yes, I've sat and watched it to check). And it also doesn't happen every time I run the hot water while the heating is off, although I must say I'm pretty paranoid about it now.
So it seems to me something is going on - possibly expansion vessel or pressure relief valve. I've read that the typical sign of expansion vessel trouble is the pressure going very high when the heating is on, but mine's not doing that - although I suppose if it was 1-1.5 cold and still rising by the ~1bar it would be?
What troubleshooting steps should I follow to try to narrow this problem down before I call in the engineer? I want to have a clearer idea of what might be happening.
Thanks so much for your help
