P
PSweeney
Hi Guys, firstly apologies for visiting just for help but I'm £90 down to British Gas and still not able to sort my central heating. The problem is a huge rumbling and expulsion of steam / air and water into the F+E tank. This noise is super loud and I can only liken it to an overfilled kettle boiling but magnified 100 times. When it does this the F+E tank fills and overlows. Before I get into this, some history;
The DHW tank and F+E are in an airing cupboard upstairs. There is about 50cm height between the F+E tanks and the highest point (towel rail). We had an issue with the system pumping over and the last engineer to visit advised raising the height of the vent and turning the pump speed down. I did this and it's been OK for approx 4 years, but the system get loads of air. I drain maybe half a rads worth from a towel rail once a week (in one go)
Recently, this huge noise appeared in the airing cupboard and it transpired it's the cold feed puking water, steam and air up the submerged cold feed pipe into the bottom of the F+E tank. Bolier cuts out but can restart via thermal switch once cooled down. British gas came to look at it and and could not diagnose the fault as it was operating fine when they called. The BG engineer tested the temp of the flow and return and differential was 11 degrees which apparently rules out blockage and sludge. This cost me £90 for 30mins consultation....the guy said he had to leave as staying longer would bump it to £280....not happy.
The problem remains and occurs maybe every other day, no discernable pattern of HW/CH etc and having researched online I now see that the open vent is on the positive side of the pump tee'd off the flow at the point it enters the motorised valve. The cold feed is 15mm pipe and connects to the flow on the negative side of the pump approx 150mm from the pump. So, reading up, it appears the vent is on the wrong side, something I may address but it does not explain why the system is now puking air / steam up the cold feed.
When this occures, the pump seems laboured and the rumbling builds up and the F+E tank height rises and overflows. Initially I switched the boiler / pump off at the wall spur and this seems to curtail the bubbling but it would only cease fully once the system has cooled.
A few nights ago, I drained the system down, water was reasonably clean. The F+E tank water was like oil, I drained the F+E and cleaned maybe 6mm of sludge from the bottom. I refilled, bleeding away with X800 (squirted down the cold feed) and it's still sat in the system hopefully doing something although I'm not convinced this is sludge / scale. One oddity when filling was the upstairs rads filled up first from the cold feed ?
I've read about combining the cold feed and vent but I want to be sure this is going to help and not be dangerous. The point at which I could combine thiem is maybe 3-4 meters from where the cold feed joins the flow on neg side of the pump. My theory on this is that the open vent position is allowing see-sawing and pulling in air, goes through the boiler and gets stuck in the pump, which is either stalled by an air lock or siezing momentarilly. Air / Steam pressure buillds as boiler overheats, then finds it's way out the system via the cold feed (as vent is on other side of the pump).
I'm due to drain the stsyem tonigth but could really do with some proper advice. I'm loathed to call BG back out and I'm struggling to find an independant engineer to take this on.
Thanks
Phil
The DHW tank and F+E are in an airing cupboard upstairs. There is about 50cm height between the F+E tanks and the highest point (towel rail). We had an issue with the system pumping over and the last engineer to visit advised raising the height of the vent and turning the pump speed down. I did this and it's been OK for approx 4 years, but the system get loads of air. I drain maybe half a rads worth from a towel rail once a week (in one go)
Recently, this huge noise appeared in the airing cupboard and it transpired it's the cold feed puking water, steam and air up the submerged cold feed pipe into the bottom of the F+E tank. Bolier cuts out but can restart via thermal switch once cooled down. British gas came to look at it and and could not diagnose the fault as it was operating fine when they called. The BG engineer tested the temp of the flow and return and differential was 11 degrees which apparently rules out blockage and sludge. This cost me £90 for 30mins consultation....the guy said he had to leave as staying longer would bump it to £280....not happy.
The problem remains and occurs maybe every other day, no discernable pattern of HW/CH etc and having researched online I now see that the open vent is on the positive side of the pump tee'd off the flow at the point it enters the motorised valve. The cold feed is 15mm pipe and connects to the flow on the negative side of the pump approx 150mm from the pump. So, reading up, it appears the vent is on the wrong side, something I may address but it does not explain why the system is now puking air / steam up the cold feed.
When this occures, the pump seems laboured and the rumbling builds up and the F+E tank height rises and overflows. Initially I switched the boiler / pump off at the wall spur and this seems to curtail the bubbling but it would only cease fully once the system has cooled.
A few nights ago, I drained the system down, water was reasonably clean. The F+E tank water was like oil, I drained the F+E and cleaned maybe 6mm of sludge from the bottom. I refilled, bleeding away with X800 (squirted down the cold feed) and it's still sat in the system hopefully doing something although I'm not convinced this is sludge / scale. One oddity when filling was the upstairs rads filled up first from the cold feed ?
I've read about combining the cold feed and vent but I want to be sure this is going to help and not be dangerous. The point at which I could combine thiem is maybe 3-4 meters from where the cold feed joins the flow on neg side of the pump. My theory on this is that the open vent position is allowing see-sawing and pulling in air, goes through the boiler and gets stuck in the pump, which is either stalled by an air lock or siezing momentarilly. Air / Steam pressure buillds as boiler overheats, then finds it's way out the system via the cold feed (as vent is on other side of the pump).
I'm due to drain the stsyem tonigth but could really do with some proper advice. I'm loathed to call BG back out and I'm struggling to find an independant engineer to take this on.
Thanks
Phil
