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#1
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CH drain tap leaking, radiator valve leaking, valve not working (?)
Hello,
I have an indirectly (?) heated CH/DHW system. There is a boiler, cylinder (hot water tank), pump and two ACL Lifestyle motorised valves. 1. I drained down the system at the drain tap. When I tried to re- close the system the tap kept on leaking. I took out the whole of the inside of the drain plug and replaced the flat, circular rubber washer having removed the old one. The drain tap still leaks, even though I have tightened it. Any other ideas on how to tackle that? 2. I replaced a couple of radiators and the CH does not heat. The DHW is fine. The radiators and pump are bled. I can feel scorching hot water from the boiler as it enters the pump. When DHW is set to on, the 22mm pipe below the valve on the DHW cylinder side of the circuit gets hot. The water pipe downstream of the valve on the CH side does not get hot even when the boiler is generating hot water and system set to "on" for CH. I guess this is a valve problem. Anything I can do to check the operation of this valve? Is this an easy part to replace? 3. One of the radiator valves leaks slightly. The valve has a push fit on the supply and two threaded parts on the body of the valve. One thread screws into the body of the radiator and the second thread connects the body of the valve to the section that screws into the radiator. It is this middle thread that connects the valve to the pipe going into the body of the radiator that leaks. I took the valve apart and saw the thread was fairly "shallow". Also the conection between the two parts was like a "shallow bowl". I cleaned the surfaces and wound a fair amount of PTFE tape around the thread. I reassembled the valve. I hand tightened, then tightened with a wrench as far as I dare. There is still a very slow leak - say one drip every 30 (?) minutes. The way I would describe the leak is that is the water is coming "up and over" the nut rather than "down and around" the nut. Any ideas? Thanks Clive |
#2
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CH drain tap leaking, radiator valve leaking, valve not working(?)
On Mon, 13 Oct 2008 23:40:44 -0700, Clive wrote:
Hello, I have an indirectly (?) heated CH/DHW system. There is a boiler, cylinder (hot water tank), pump and two ACL Lifestyle motorised valves. 1. I drained down the system at the drain tap. When I tried to re- close the system the tap kept on leaking. I took out the whole of the inside of the drain plug and replaced the flat, circular rubber washer having removed the old one. The drain tap still leaks, even though I have tightened it. Any other ideas on how to tackle that? Bits of the disintegrated old washer still stuck in the valve preventing the new washer seating properly? Rubber washer over-tightened when system hot and squeezing off its seat? (Usually ****es out if you do this.) Failing that replace the DOC. 2. I replaced a couple of radiators and the CH does not heat. The DHW is fine. The radiators and pump are bled. I can feel scorching hot water from the boiler as it enters the pump. When DHW is set to on, the 22mm pipe below the valve on the DHW cylinder side of the circuit gets hot. The water pipe downstream of the valve on the CH side does not get hot even when the boiler is generating hot water and system set to "on" for CH. I guess this is a valve problem. Anything I can do to check the operation of this valve? Is this an easy part to replace? There's a lever on the valve to open it manually - try that. Otherwise it suggests an air-lock somewhere preventing hot water circulating around the rads. Is there an air bleed valve on a vertical leg of pipework somewhere you've missed, or an automatic air bleed valve that's got its dust cap screwed down or is not automatically bleeding? (Try loosening its screwed cap to see if that lets air out.) 3. One of the radiator valves leaks slightly. The valve has a push fit on the supply and two threaded parts on the body of the valve. One thread screws into the body of the radiator and the second thread connects the body of the valve to the section that screws into the radiator. It is this middle thread that connects the valve to the pipe going into the body of the radiator that leaks. I took the valve apart and saw the thread was fairly "shallow". Also the conection between the two parts was like a "shallow bowl". I cleaned the surfaces and wound a fair amount of PTFE tape around the thread. I reassembled the valve. I hand tightened, then tightened with a wrench as far as I dare. There is still a very slow leak - say one drip every 30 (?) minutes. The way I would describe the leak is that is the water is coming "up and over" the nut rather than "down and around" the nut. It's a compression fitting, with an olive (like a plain wedding ring) on the tubular section of the 'tail' that screws into the rad. The olive can be set at a range of positions along the tubular bit. Have you got it right at the end, almost off the tube? It should be far enough along that there's some of the tube sticking into the mating part of the valve body. (Have a look at how any other compression fitting works so you know how it's supposed to be.) -- YAPH http://yaph.co.uk Things don't like being anthropomorphised. |
#3
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CH drain tap leaking, radiator valve leaking, valve not working(?)
On 14 Oct, 09:07, YAPH wrote:
Bits of the disintegrated old washer still stuck in the valve preventing the new washer seating properly? Rubber washer over-tightened when system hot and squeezing off its seat? (Usually ****es out if you do this.) Failing that replace the DOC. Following your lead I had a good look inside the body of the tap, wearing my trusty camper's head torch for lighting. Near the drain "part" that comes off at an angle from the threaded "part" I saw some "crap" that wouldn't budge by scraping. I fitted a wood drill bit into my electric screwdriver and set to work on the "crap" trying to avoid the thread on the body of the tap. After about 30 seconds the "crap" dislodged. The "crap" turned out to be a blob of solder from when the drain tap was fitted. How the thing ever sealed in the first place I don't know. I refitted the washer to the threaded "part", reassembled and closed the tap, just hand tightening - and bingo, by jingo, no leak. Hooray! Hooray! As a by-product, when I do drain the system (at which I am becoming most adept), the water just gushes out of the drain when the tap is opened. Before the drain rate was a dribble and took over an hour. Draining of the CH system can now be doen in 10 minutes. I had already bought a replacement drain tap for £2 but fitting it would have involved cutting off the old one that was soldered on - which would then have made the pipe too short - which would have involved fitting on a new length of pipe to fit the new drain tap .... There's a lever on the valve to open it manually - try that. Otherwise it suggests an air-lock somewhere preventing hot water circulating around the rads. Is there an air bleed valve on a vertical leg of pipework somewhere you've missed, or an automatic air bleed valve that's got its dust cap screwed down or is not automatically bleeding? (Try loosening its screwed cap to see if that lets air out.) On the body of the valve there is a side lever and a top lever. The top lever seems very "loose" and the side lever resists manual adjustment. I don't want to break them by forcing them so I haven't manually adjusted the valves. I can't find another air bleed on the pipework - doesn't mean there isn't one. There does seem to be an automatic bleed next to the boiler - it is covered in what looks like limestone ! I guess the valve has overflowed (from time-to-time) and this deposit built up. I have no idea if this valve now works. I underscrewed the dust cap but nothing seemed to happen. Having talked to a couple of people we now thing the pump maybe faulty. The argument goes: I put X400 desludger in the system a couple of weeks ago which may have dislodged some material that has become lodged in the pump When I touch the back of the pump, where I think the mechanical impeller is situated, it gets hot when the boiler is on The water pipe supplying the pump from the boiler gets hot quickly when the boiler is on - obviously The pipes "downstream" of the valves get hot when the controller signals the selected circuit, CH or DHW, to be working. So that seems to indicate everything should work .... Now, is it possible when the DHW valve is open that heat is getting to the HW cylinder by conduction along the (really hot) metal pipes and just a passive expansion and hence movement of the heated water which is then cooled by the water that surrounds it in the cylinder? Similarly, when the CH valve is open, a similar mechanism would cause the radiator near the boiler to be hot, the next one tepid but not cold and in the rest of the house the rads are at room temperature? The pump can be isolated by two valves either side so will be easy to remove (haven't tried yet, ha !) . It's a compression fitting, with an olive (like a plain wedding ring) on the tubular section of the 'tail' that screws into the rad. The olive can be set at a range of positions along the tubular bit. Have you got it right at the end, almost off the tube? It should be far enough along that there's some of the tube sticking into the mating part of the valve body. (Have a look at how any other compression fitting works so you know how it's supposed to be.) Finally the leak seems to have stopped. I'm really nervous about disassembling it again and possibly recreating a leak - especially based on the problems I have experienced with the drain tap leaking. I know that is ignoring something that might flare up in the future but let sleeping dogs lie. Clive |
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