....if they can help with the following issue.
I have a big problem with my CH system losing pressure and gaining air, and it's driving me nuts and, tbh, the plumber I'm using is now looking to me for suggestions as to how to fix it and I'm out of Google-based solutions.
Background:
I have a sealed CH system, but the HW is open vent (small F&E tank in the loft). The boiler is a system (not combi) Camray 5 50/70 (50,000 - 70,000 BTU) wall-hung, internal, oil-fired boiler - about 10 years old - serviced every year. I have a HW tank and a single pump (new - see below), two motorised valves (which both seem to work ok) and a (new - see below) expansion vessel in the airing cupboard on the first floor. I now have 14 rads in total (with two having been very recently fitted).
I've recently bought this property and had two new rads fitted - one on the first floor and roughly the same height as the pump etc, and one in a loft conversion - clearly higher. The flow pipe has been tee'd off the main CH flow just downstream of the CH motorised valve, and the return tees into the main collecting returning pipe. I've now had a non-return valve fitted on the new return section since the pipework was getting hot when just the HW was on. The pipework for both these new rads goes up from the airing cupboard, around the eaves and drops down the wall to the new rad on the first floor landing and continues round (in parallel, not series) to the rad in the loft conversion. A new beefier Grundfos pump was fitted to get the water up a storey and to cope with two additonal rads.
Problem:
I continually get air in the system - as evidenced by massive gurgling in the pipework down to the new landing rad (as well as elsewhere); and lose loads of pressure 1.4bar cold pressure down to 0.8bar cold pressure in 24 hours - but then, weirdly, it seems to tail off, never getting lower than 0.7 bar.
Attempted fixes:
1 Look for leaks inside - none; though some of the pipework runs under a concrete floor. Pipes and floor laid 9 years ago. (Arrrggghhh...don't tell me)
2 Look for leaks in boiler - none apparent, and there's no overflow pipe for expanded water coming from the boiler
3 Look for leak from overflow pipe from pressure relief valve on top of expansion vessel. Ah ha! It leaks...and, on checking the pressure the hot pressure is 2.8 bar. Bugger me, that seems like a massive increase in pressure from the cold pressure of 1.4 bar! So - google search. Google says that the difference in pressure between cold and hot s/be 0.3-0.6 bar (not 1.4 bar). main cause for fault? Knackered expansion vessel. OK - let's change the expansion vessel. OK - what size Expansion vessel should I get? Google says s/be measured by volume of water in the system (wtf - how do I know?!) OR, rough rule of thumb, = 1.5 -2.0 litres per rad, or 1 litre per KW of boiler. OK! 14 rads = 21-28 litres; boiler = 21 KW max. Google also says you can't have one that's too big, but you can have one that's too small. So... let's get a 24 litre expansion vessel, with attached new pressure relief valve, in case the existing prv is buggered having been opened and closed several times. Done, and fitted. Air side pressure is left at manufacturer's factory setting of 1.5 bar. System pressurised to 1.4 bar cold. Run system last night - very quiet, no problems - hot pressure maxes at 1.9 bar. Ah ha! I've fixed it! Nope - this morning, the cold pressure is back down to 0.75 bar. Aaaargh.
Questions:
1 WTF is going on?
2 Specifically, I can think of only two possible solutions: a) the hot water loop and CH loop in the HW cylinder is breached and water is flowing from CH to HW under pressure. My plumber, in whom I am losing trust, says it can't be that since I'd smell the inhibitor which he put in only 3 weeks ago from the CH system in the hot water when I run a HW tap. b) I have a massive leak in the pipework embedded in the concrete floor.
Are there other possible causes for these symptoms?
Is it true that I'd def smell the inhibitor in the HW flow if the loops have been breached?
Is the only way to tell if the under-concrete pipes are leaking to get a thermal camera? If they are leaking - is there any way to solve the problem other than digging the floor up?
How come the cold water pressure stabilises at about 0.7 bar - if there's a leak - why isn't it diminishing to zero??
Thanks for reading - as I say - a beer/donation/eternal gratitude extended to any plumber who fancies replying.... I'm going kin nuts now.
I have a big problem with my CH system losing pressure and gaining air, and it's driving me nuts and, tbh, the plumber I'm using is now looking to me for suggestions as to how to fix it and I'm out of Google-based solutions.
Background:
I have a sealed CH system, but the HW is open vent (small F&E tank in the loft). The boiler is a system (not combi) Camray 5 50/70 (50,000 - 70,000 BTU) wall-hung, internal, oil-fired boiler - about 10 years old - serviced every year. I have a HW tank and a single pump (new - see below), two motorised valves (which both seem to work ok) and a (new - see below) expansion vessel in the airing cupboard on the first floor. I now have 14 rads in total (with two having been very recently fitted).
I've recently bought this property and had two new rads fitted - one on the first floor and roughly the same height as the pump etc, and one in a loft conversion - clearly higher. The flow pipe has been tee'd off the main CH flow just downstream of the CH motorised valve, and the return tees into the main collecting returning pipe. I've now had a non-return valve fitted on the new return section since the pipework was getting hot when just the HW was on. The pipework for both these new rads goes up from the airing cupboard, around the eaves and drops down the wall to the new rad on the first floor landing and continues round (in parallel, not series) to the rad in the loft conversion. A new beefier Grundfos pump was fitted to get the water up a storey and to cope with two additonal rads.
Problem:
I continually get air in the system - as evidenced by massive gurgling in the pipework down to the new landing rad (as well as elsewhere); and lose loads of pressure 1.4bar cold pressure down to 0.8bar cold pressure in 24 hours - but then, weirdly, it seems to tail off, never getting lower than 0.7 bar.
Attempted fixes:
1 Look for leaks inside - none; though some of the pipework runs under a concrete floor. Pipes and floor laid 9 years ago. (Arrrggghhh...don't tell me)
2 Look for leaks in boiler - none apparent, and there's no overflow pipe for expanded water coming from the boiler
3 Look for leak from overflow pipe from pressure relief valve on top of expansion vessel. Ah ha! It leaks...and, on checking the pressure the hot pressure is 2.8 bar. Bugger me, that seems like a massive increase in pressure from the cold pressure of 1.4 bar! So - google search. Google says that the difference in pressure between cold and hot s/be 0.3-0.6 bar (not 1.4 bar). main cause for fault? Knackered expansion vessel. OK - let's change the expansion vessel. OK - what size Expansion vessel should I get? Google says s/be measured by volume of water in the system (wtf - how do I know?!) OR, rough rule of thumb, = 1.5 -2.0 litres per rad, or 1 litre per KW of boiler. OK! 14 rads = 21-28 litres; boiler = 21 KW max. Google also says you can't have one that's too big, but you can have one that's too small. So... let's get a 24 litre expansion vessel, with attached new pressure relief valve, in case the existing prv is buggered having been opened and closed several times. Done, and fitted. Air side pressure is left at manufacturer's factory setting of 1.5 bar. System pressurised to 1.4 bar cold. Run system last night - very quiet, no problems - hot pressure maxes at 1.9 bar. Ah ha! I've fixed it! Nope - this morning, the cold pressure is back down to 0.75 bar. Aaaargh.
Questions:
1 WTF is going on?
2 Specifically, I can think of only two possible solutions: a) the hot water loop and CH loop in the HW cylinder is breached and water is flowing from CH to HW under pressure. My plumber, in whom I am losing trust, says it can't be that since I'd smell the inhibitor which he put in only 3 weeks ago from the CH system in the hot water when I run a HW tap. b) I have a massive leak in the pipework embedded in the concrete floor.
Are there other possible causes for these symptoms?
Is it true that I'd def smell the inhibitor in the HW flow if the loops have been breached?
Is the only way to tell if the under-concrete pipes are leaking to get a thermal camera? If they are leaking - is there any way to solve the problem other than digging the floor up?
How come the cold water pressure stabilises at about 0.7 bar - if there's a leak - why isn't it diminishing to zero??
Thanks for reading - as I say - a beer/donation/eternal gratitude extended to any plumber who fancies replying.... I'm going kin nuts now.