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- 21 Sep 2015
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TLDR version - I've got a leak rate of 0.4 bar/hour at the balanced supplies but only when the system is lined out fully with the mains cold valve closed. If I test each system individually no leak is found.
Long version -
I've recently had a full re-plumb about a year ago when we bought our house. I'm fairly capable with plumbing (I work with industrial gas process / small bore tubing) but as I don't generally do soldered joints and there was such a lot to do (and I'm not qualified for domestic) I got a plumber in. He said he'd tested the system and I had no reason to doubt it. Last week I pulled out a couple of radiators and moved a hot and cold tap fed by a balanced supply from an unvented cylinder. 9 soldered joints in total. Afterwards I tested the system as follows:-
First Test:
Gauge at washing machine fitting (balanced cold)
Isolated Incoming Main Cold Supply
Observed 0.4 bar drop over an hour.
Second Test:
Gauge at washing machine fitting (balanced cold)
Isolated Incoming Main Cold Supply
Isolated Main Cold Supply to combination valve at the cylinder.
Vented Main Cold (so testing this time everything downstream of the combination valve)
No pressure drop observed
So at this point I thought I'd narrowed the leak down to the main cold supply line up to the combination valve so I did another test.
Third Test:
Gauge at outside tap (fed from mains cold):-
Isolated Incoming Main Cold Supply
Isolated Main Cold Supply at combination valve
Vented balanced hot/cold (so testing only the mains cold supply envelope up to the cylinder).
No pressure drop observed.
Any pointers appreciated. I'm thinking there must be something I'm missing with how the combination valve regulates the downstream pressure, but I can't fathom it!
Long version -
I've recently had a full re-plumb about a year ago when we bought our house. I'm fairly capable with plumbing (I work with industrial gas process / small bore tubing) but as I don't generally do soldered joints and there was such a lot to do (and I'm not qualified for domestic) I got a plumber in. He said he'd tested the system and I had no reason to doubt it. Last week I pulled out a couple of radiators and moved a hot and cold tap fed by a balanced supply from an unvented cylinder. 9 soldered joints in total. Afterwards I tested the system as follows:-
First Test:
Gauge at washing machine fitting (balanced cold)
Isolated Incoming Main Cold Supply
Observed 0.4 bar drop over an hour.
Second Test:
Gauge at washing machine fitting (balanced cold)
Isolated Incoming Main Cold Supply
Isolated Main Cold Supply to combination valve at the cylinder.
Vented Main Cold (so testing this time everything downstream of the combination valve)
No pressure drop observed
So at this point I thought I'd narrowed the leak down to the main cold supply line up to the combination valve so I did another test.
Third Test:
Gauge at outside tap (fed from mains cold):-
Isolated Incoming Main Cold Supply
Isolated Main Cold Supply at combination valve
Vented balanced hot/cold (so testing only the mains cold supply envelope up to the cylinder).
No pressure drop observed.
Any pointers appreciated. I'm thinking there must be something I'm missing with how the combination valve regulates the downstream pressure, but I can't fathom it!
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