hmv4u
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Posts: 145
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Post by hmv4u on May 20, 2019 23:30:23 GMT
A few years ago I swapped the gate valve feeding the indirect hot water tank because it wouldn't turn off completely and installed a ball valve,recently while doings some pipework alterations on the bathroom hot water pipe I noticed it still dribbled a bit and assumed the new valve was faulty and have bought a new one,I have just had the horrible thought that it might not be the valve but the internal coil leaking(its 23 years old) is that a possibility and how would I find out ?
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Post by crowsfoot on May 21, 2019 6:29:51 GMT
It is possible it could be the coil,do bear in mind though even new gate valves only shut of 99% (you're always better draining the tank if you're doing some plumbing work on the hot).
I'm guessing that the two tanks are at the same level, hence not a persistent drip from an overflow due to a defective coil.
If they are, tie up the ball-valve to one of them and empty the tank, give if half an hour and if the tanks filled up a little it's more than likely to be a defect in the coil.
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Post by tomplum on May 21, 2019 7:42:15 GMT
when you shut off the hot water with the gate valve/ lever valve, the valve will shut but the pipe is still full of water that is trapped in air pockets where the hot water draw off pipes rises and falls, I agree with Tappy though, the way to find out if its the coil is, do as Tappy says,
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hmv4u
Full Member
Posts: 145
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Post by hmv4u on May 21, 2019 15:54:42 GMT
It is possible it could be the coil,do bear in mind though even new gate valves only shut of 99% (you're always better draining the tank if you're doing some plumbing work on the hot). I'm guessing that the two tanks are at the same level, hence not a persistent drip from an overflow due to a defective coil. If they are, tie up the ball-valve to one of them and empty the tank, give if half an hour and if the tanks filled up a little it's more than likely to be a defect in the coil. Thanks much appreciated,I have had a look up the loft and the tanks(one expansion and 2 linked cold water ones ) are on the same level but both water levels are below the overflow- Just to be clear then if the coil was leaking then the CH water would force the DHW up the expansion pipe into the cold water tanks ,the water level would gradually rise (if no HW is used) and go out the overflow ? Was a bit surprised by the 99% shut off bit, is this generally just gate valves or are ball valves the same as I thought they where virtually perfect (barring manufacturing defects ) -I will take on board the emptying the tank as well,i used rubber bungs last time or as a old plumber once told me use a carrot & potato-thought he was taking the piss until he lent me the rubber equivalent |
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Post by tomplum on May 21, 2019 16:51:00 GMT
gate valves have a horrible reputation for not shutting off because of lime build up, ball type lever valves are generally good but even they get build ups too, lime and debris are not choosy, they stick to anything poking out in pipework,  |
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hmv4u
Full Member
Posts: 145
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Post by hmv4u on Jun 1, 2019 19:47:40 GMT
today I decided to replace the ball valve feeding the hot water cylinder as I'd bought one anyway,I turned off the valve and opened the upstairs hot water and it ran then slowed to a trickle but wouldn't stop so I went up and stuck a rubber bung into the outflow but it still dribbled,I tried a second bung and no different so I did as crowsfoot suggested and emptied the twin cold water tanks with a hose out of the loft and down the toilet,the drip continued,I went downstairs and opened the hot water tap/s and ran till it went to a drip (an intermittent dribble then drip) but again it still continued and I left it a while,I changed the valve anyway but ran out of time so had to refill the cold water tanks.
I assumed that if the coil was leaking it would be coming out of the expansion tank but there wasn't any flow from the ball cock, is there also a feed into the boiler/system besides the expansion tank ?
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Post by tomplum on Jun 2, 2019 10:21:47 GMT
I've been giving this some thought hmv4u and am now thinking that, there may be a mixer tap or shower valve passing through the body, To rule this out, next time you try turning off the hot, shut the incomeing main as well, so if the dribble stops, the cold main is mixing with the hot water, I think  |
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hmv4u
Full Member
Posts: 145
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Post by hmv4u on Jun 2, 2019 12:17:26 GMT
Bloody hell Tom,you have my vote for celebrity porn star,sorry ,plumber ! I decided to have a go straight away as my wallet was starting to fret over the thought of the expense.
So I turned off the new hot water feed and went downstairs and turned on the hot water and after a minute the water slowed to a constant drip as before,went up into the loft and the expansion tank was ok but the mains cold water was drip feeding by the same amount,thinking about what you said I realised the only other feed out of it was to the shower pump so i closed it off ,back downstairs and the constant drip had slowed right down to about 1 a second but wouldn't stop so I turned off the mains and after a pause and opening the mains cold taps briefly upstairs that stopped completely ! (not sure why but presume there's something else bypassing as well ?)
When I turned it back on, still ok no drips but when I turned the shower feed back on it started dripping again,so from what you have said the cold water is feeding through the cold side of the pump up through the shower valve(even turned off) back down and through the hot side of the pump up into the cylinder and back into the DH water ?
thanks for you help
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Post by tomplum on Jun 2, 2019 13:06:07 GMT
you're welcome pal, anytime.
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