Hello All
And debug ideas/suggestion very welcome - I have run out of them .....
I have moved into a new house Oct 22 and it has an old, but "good" functional BG 330+ boiler (serviced when I moved in), however it has started to F22 dry fault error. I have read as much as I can on forums here and else where, manuals and eng debug guides and cannot resolve or identify the root case issue and fix it. I am going to be replacing the whole heating system post this winter/spring therefore im really wanting to hold this out as much as possible.
It had been running fine through the first part of the winter then, "F22"d once in Nov .. I read/understood/checked the implications and proved that it was not "dry" before poking the reset button the boiler and it continued fine for weeks. 1 month later it randomly occurred again and then over the following weeks started to occur every night (different times not associated with external temps or timer/calls for HW/CH).
A reset or boiler power cycle always resolves the issue and the boiler continues for hours, days and sometimes weeks.
Over this time I have tried to check, debug and root cause the issue. I have had "some" effect on it but cannot nail it.
Some background statements and things I have tried:
- There is a new Grunfoss UPS2 pump fitted within 6months prior (I have the receipt) / when the system is running the pump is silent and performing well. Therefore I am strongly doubting that the pump is at fault (its on setting 2, I have not tried it on 1 or 3 - the rad system heats up reasonably and if anything its a little under powered/sized for the number of rads/size of the runs) - give that it worked fine for most of oct/nov/dec it supports me ruling this out.
- The 18l Zilman pressure vessel/expansion tank (old 2008) was originally showing 1bar when I moved in and not dropping, or not needed topping up. I have bleed rads/pumps/values a few times and never got any any air out so doubting an airlock - before it started happening nightly I had not touched or affected the closed water system at all. Early Jan I dropped the water pressure out of the pressure vessel via the filler hose and checked the bladder air pressure. It was 0.4 bar, therefore I thought I have found the problem - I was going to change it there and then, but decided to air pump it back up to 1.5bar - there was no bubbling and it pumped back up well to 1.5bar, held air pressure for 3 hours perfectly before I decided to fill the water back up and re-pressure water side to 1.5bar. The system then ran well again no F22 for 6 days (really thought I had nailed it) - no water pressure drop at all. Then it occurred again a couple of times over a week. At the weekend I again dropped the water pressure, expecting to find the air pressure on the bladder to be gone, but it wasnt! it was still perfectly at 1.5bar!!!)
- I have checked all the wiring harnesses/connectors to the thermistors and check the resistances are within tolerance and aligned with the temp deltas from flow/return - and they are nicely fitted to the pipes.
- There is a mag filter on the system and that is clean as a whistle, as is all the bleed water and a test from the bottom of the ground floor rads
- When the boiler "F22"'s I have checked the "state" d99 from the diag menu and every time the boiler is in the S.98 "Flow/Return Sensor check is running, demand (dhw or heating) is blocked" - Description "Check flow & return thermistor connections to the pipes. Check harness connection to the thermistor. Check the wires are not trapped between any internal components.
- If it was a PCB or thermistor fault I would expect it to be a little more frequent. I do find it quite a rubbish "test" to detect a dry system that the delta of the temp gradients are used between flow/return to infer pressure in the system. I can/could guess that the pump speed would affect it, but again I would expect that to be associated with temp in the loft (where the tanks/pumps/valves are)
- I have temp probes on all the pipes and track/monitor graph them via "home assistant" as well as all the system calls for heat, probing the wiring centre. Nothing really unusual.
- A couple of pumb shops and engineers in said shops have suggested ignition sensors or gas pressure sensors, but the flow/debug guides in the manuals dont really make that make sense.
So any thoughts - it would be VERY appreciated.
Thank you
Jamie
And debug ideas/suggestion very welcome - I have run out of them .....
I have moved into a new house Oct 22 and it has an old, but "good" functional BG 330+ boiler (serviced when I moved in), however it has started to F22 dry fault error. I have read as much as I can on forums here and else where, manuals and eng debug guides and cannot resolve or identify the root case issue and fix it. I am going to be replacing the whole heating system post this winter/spring therefore im really wanting to hold this out as much as possible.
It had been running fine through the first part of the winter then, "F22"d once in Nov .. I read/understood/checked the implications and proved that it was not "dry" before poking the reset button the boiler and it continued fine for weeks. 1 month later it randomly occurred again and then over the following weeks started to occur every night (different times not associated with external temps or timer/calls for HW/CH).
A reset or boiler power cycle always resolves the issue and the boiler continues for hours, days and sometimes weeks.
Over this time I have tried to check, debug and root cause the issue. I have had "some" effect on it but cannot nail it.
Some background statements and things I have tried:
- There is a new Grunfoss UPS2 pump fitted within 6months prior (I have the receipt) / when the system is running the pump is silent and performing well. Therefore I am strongly doubting that the pump is at fault (its on setting 2, I have not tried it on 1 or 3 - the rad system heats up reasonably and if anything its a little under powered/sized for the number of rads/size of the runs) - give that it worked fine for most of oct/nov/dec it supports me ruling this out.
- The 18l Zilman pressure vessel/expansion tank (old 2008) was originally showing 1bar when I moved in and not dropping, or not needed topping up. I have bleed rads/pumps/values a few times and never got any any air out so doubting an airlock - before it started happening nightly I had not touched or affected the closed water system at all. Early Jan I dropped the water pressure out of the pressure vessel via the filler hose and checked the bladder air pressure. It was 0.4 bar, therefore I thought I have found the problem
- I was going to change it there and then, but decided to air pump it back up to 1.5bar - there was no bubbling and it pumped back up well to 1.5bar, held air pressure for 3 hours perfectly before I decided to fill the water back up and re-pressure water side to 1.5bar. The system then ran well again no F22 for 6 days (really thought I had nailed it) - no water pressure drop at all. Then it occurred again a couple of times over a week. At the weekend I again dropped the water pressure, expecting to find the air pressure on the bladder to be gone, but it wasnt! it was still perfectly at 1.5bar!!!)- I have checked all the wiring harnesses/connectors to the thermistors and check the resistances are within tolerance and aligned with the temp deltas from flow/return - and they are nicely fitted to the pipes.
- There is a mag filter on the system and that is clean as a whistle, as is all the bleed water and a test from the bottom of the ground floor rads
- When the boiler "F22"'s I have checked the "state" d99 from the diag menu and every time the boiler is in the S.98 "Flow/Return Sensor check is running, demand (dhw or heating) is blocked" - Description "Check flow & return thermistor connections to the pipes. Check harness connection to the thermistor. Check the wires are not trapped between any internal components.
- If it was a PCB or thermistor fault I would expect it to be a little more frequent. I do find it quite a rubbish "test" to detect a dry system that the delta of the temp gradients are used between flow/return to infer pressure in the system. I can/could guess that the pump speed would affect it, but again I would expect that to be associated with temp in the loft (where the tanks/pumps/valves are)
- I have temp probes on all the pipes and track/monitor graph them via "home assistant" as well as all the system calls for heat, probing the wiring centre. Nothing really unusual.
- A couple of pumb shops and engineers in said shops have suggested ignition sensors or gas pressure sensors, but the flow/debug guides in the manuals dont really make that make sense.
So any thoughts - it would be VERY appreciated.
Thank you
Jamie
