R
rkanaga
I've finally got to the bottom of my recurrent air/ gas problem…..
To recap..
http://www.ukplumbersforums.co.uk/central-heating-forum/55434-air-open-vented-system-new-post.html
We have an open vented fully pumped system with a 3 year old Vaillant Ecotec condensing boiler which replaced an ageing non condensing boiler in a 30 year old system.
About 7 months ago we had a slow leak from an underflow rad feed pipe buried in screen. This was dug up, cut out and a new section of pipe welded in. Unfortunately as this was a slow leak it had probably been going on for at least a month and so major drying out works were required before we could put the flooring down again etc, Very very traumatic to say the least! Thankfully although the pipes were buried in screed the leak was due to the pipe having been bent to go round a gas pipe (! yes I know!) and the rest of the pipe was fine. Furthemore the pipes were correctly wrapped in denzo tape and were in good condition so (fingers crossed!) I hope that we are not going to have problems with pipes corroding from the outside everywhere under the screed.
Anyhow since then we have had recurring problems with pumps becoming noisy and air in he system
BG have come a number of times and simply fit a new pump which is not a permanent solution.
Finally a more diligent BG guy came round and took the pump head off. This showed that the pump vanes were full of metallic crud. He cleaned the pump as a temporary measure. Clearly the problem is corrosion in the system.
BG are now proposing fitting a magnetic filter to filter any remaining debris.
The heat exchanger is almost certainly at least partially clogged as when we first got the pump working again the boiler was knocking loudly. It was better if you set the temp to a lower setting. This has improved now however and the system seems to be able to draw water through the boiler with a set temp of 62 degrees.
Gas is sell accumulating in the system both at the bleed valve by the hot water cylinder and in one particular rad upstairs. The rad upstairs only accumulates air when the central heating has been pumping, not when we have been using hot water only.
The system is not leaking now as I have tied up the header valve and the level does not drop.
My question/ concerns are as follows:
I am paranoid about not getting further leaks after the trauma to the family (with small kids) of 4 months of drying out and repairs last time.
Why is gas still being made? No new water is being drawn into the system and Sentinex was put in after the leak was repaired. Why is the system still corroding? Surely the fact that no fresh water is being drain in and Sentinex was put in after the system was refilled should prevent this? Is the presence of magnetite crud in the system (presumably at the bottom of radiators and/or in the heat exchanger) feeding this process?
Is draining the system down and fitting a magnetic filter the right thing to do? Should we have the system flushed with cleaner etc as well (given that the system will be drained to fit the filter?)
Should we pre-emptively change the heat exchanged in the Vaillant? (the part seems to be about £90, but I'm not sure about the labour. Again the system is going to be drained anyway so would it make sense to get this done at the same time?)
Above all what can we do to minimise the chance of further leaks? Will the corrosion affect the steel rads only (bad but not catastrophic) or are the aluminium rads (Farral type) and (heaven forbid) the copper pipes (some of which are as I said underfloor!) at risk as well?
Thank you so much for any help. I desperately want to make the best choice quickly to end this nightmare!
Robin.
To recap..
http://www.ukplumbersforums.co.uk/central-heating-forum/55434-air-open-vented-system-new-post.html
We have an open vented fully pumped system with a 3 year old Vaillant Ecotec condensing boiler which replaced an ageing non condensing boiler in a 30 year old system.
About 7 months ago we had a slow leak from an underflow rad feed pipe buried in screen. This was dug up, cut out and a new section of pipe welded in. Unfortunately as this was a slow leak it had probably been going on for at least a month and so major drying out works were required before we could put the flooring down again etc, Very very traumatic to say the least! Thankfully although the pipes were buried in screed the leak was due to the pipe having been bent to go round a gas pipe (! yes I know!) and the rest of the pipe was fine. Furthemore the pipes were correctly wrapped in denzo tape and were in good condition so (fingers crossed!) I hope that we are not going to have problems with pipes corroding from the outside everywhere under the screed.
Anyhow since then we have had recurring problems with pumps becoming noisy and air in he system
BG have come a number of times and simply fit a new pump which is not a permanent solution.
Finally a more diligent BG guy came round and took the pump head off. This showed that the pump vanes were full of metallic crud. He cleaned the pump as a temporary measure. Clearly the problem is corrosion in the system.
BG are now proposing fitting a magnetic filter to filter any remaining debris.
The heat exchanger is almost certainly at least partially clogged as when we first got the pump working again the boiler was knocking loudly. It was better if you set the temp to a lower setting. This has improved now however and the system seems to be able to draw water through the boiler with a set temp of 62 degrees.
Gas is sell accumulating in the system both at the bleed valve by the hot water cylinder and in one particular rad upstairs. The rad upstairs only accumulates air when the central heating has been pumping, not when we have been using hot water only.
The system is not leaking now as I have tied up the header valve and the level does not drop.
My question/ concerns are as follows:
I am paranoid about not getting further leaks after the trauma to the family (with small kids) of 4 months of drying out and repairs last time.
Why is gas still being made? No new water is being drawn into the system and Sentinex was put in after the leak was repaired. Why is the system still corroding? Surely the fact that no fresh water is being drain in and Sentinex was put in after the system was refilled should prevent this? Is the presence of magnetite crud in the system (presumably at the bottom of radiators and/or in the heat exchanger) feeding this process?
Is draining the system down and fitting a magnetic filter the right thing to do? Should we have the system flushed with cleaner etc as well (given that the system will be drained to fit the filter?)
Should we pre-emptively change the heat exchanged in the Vaillant? (the part seems to be about £90, but I'm not sure about the labour. Again the system is going to be drained anyway so would it make sense to get this done at the same time?)
Above all what can we do to minimise the chance of further leaks? Will the corrosion affect the steel rads only (bad but not catastrophic) or are the aluminium rads (Farral type) and (heaven forbid) the copper pipes (some of which are as I said underfloor!) at risk as well?
Thank you so much for any help. I desperately want to make the best choice quickly to end this nightmare!
Robin.