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Plumbing
Leaking drain valve on CH system
Anonymous user 1 July 2019 - 2.15 PM
Hello, I my external central heating drain valve is leaking (constant drips). Am I okay to completely unscrew the drain valve head and replace the washer to see if this fixes it - whilst still having water in the central heating system? I know water will be gushing out once i open it up and remove the head to get to the washer but hopefully it'll be a quick swap and i can screw it back in and close off the valve. Just wasn't sure if this is a bad thing to do and I should drain the water completely before messing with the drain valve in case it'll cause more issues. Thank you
6 answers from MyBuilder tradespeople
you could do that,it will gush out and you will have to top up system if its a combi,if it is tank fed it will top itself up,sometimes it is hard to get washer out especially if it is a soldered in drain cock and it was soldered in without removing the head with washer,as they tend to melt and stick onto the orifice.
Answered
1 July 2019
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I would recommend draining the system to carry out the repair if tightening the valve it does not work. If its an open vented system you can temporarily bung the feed and open vent to minimise water and inhibitor loss of out the system. If you are feeling brave and do attempt to carry the work out while the system is full, make sure the heating is off and cooled down to avoid any burns to yourself. release any pressure if its a sealed CH system before completely removing the spindle and you will probably need an extra pair of hands available too... just in case :)
Answered
1 July 2019
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You need to release the pressure if it’s a sealed/pressurised system first . it would then be much easier to change it and yes the washer can be changed. You may need something thin or a thin hook to remove the washer as they’re infamous for getting stuck. If it’s a gravity fed system you can ‘bung’ the f&e so you wont need to drain the system and then change the valve or cut in a new valve. Personally I’d get a professional in as it could go quite wrong if you’re not sure.
Answered
2 July 2019
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Hi, try to get the same type of drain valve and remove the plug. With the heating system on cold, not hot, remove the old plug and put your thumb over the valve to stop the water. Quickly remove your thumb and screw in the new plug. This is what we plumbers call a snatch! If you do have to drain down the system, remember to bleed air from all the radiators. Only do this with the boiler switched off, or the pump will circulate trapped air around your heating system. It's also very important to add new inhibitor to the water too.
Answered
2 July 2019
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To change the washer, do not attempt to unscrew , you'll be flooded out. Drain down system first. Instead of replacing just the washer, buy a new drain off complete, and change the entire inner body, that way you know it'll be sound for future reference.
Answered
2 July 2019
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hi, try a spanner on it first tighten it up , if no play drain done system and have a look . thks.
Answered
1 July 2019
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