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what do i have to do to drain my heating system as i need to take my radiator off to replace a valve which is bust? some one please help. thank you.
draining system
- Thread starter deadlynapalm
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It depends on what type of system you have.
If it is open vented (has a cold feed and expansion header tank), then you need to tie up the header tank's ball valve, to prevent the system refilling as you drain it. Connect a length of garden hose between the drain cock (which should be found at the lowest point in the system) and an outside drain, and open the drain cock.
When refilling, vent all the air from the radiators, boiler, pump and any other venting points in your system, and add a corrosion inhibitor.
With an open vented system, you may be able to change the valve without draining the system by using a pair of rubber bungs (obtainable from plumber's merchants) to seal the cold feed and expansion pipes at the header tank. This works on a similar principle to holding a coaster on a tumbler full of water and inverting it - when you let go of the coaster the water is held in by atmospheric pressure (if air cannot get it then the water cannot get out).
An alternative approach, which also works with an unvented system (one that has a sealed expansion vessel instead of a header tank), is to freeze the pipe just below the radiator valve. Aerosol kits for doing this are available for under £10. For example, look HERE.
If it is open vented (has a cold feed and expansion header tank), then you need to tie up the header tank's ball valve, to prevent the system refilling as you drain it. Connect a length of garden hose between the drain cock (which should be found at the lowest point in the system) and an outside drain, and open the drain cock.
When refilling, vent all the air from the radiators, boiler, pump and any other venting points in your system, and add a corrosion inhibitor.
With an open vented system, you may be able to change the valve without draining the system by using a pair of rubber bungs (obtainable from plumber's merchants) to seal the cold feed and expansion pipes at the header tank. This works on a similar principle to holding a coaster on a tumbler full of water and inverting it - when you let go of the coaster the water is held in by atmospheric pressure (if air cannot get it then the water cannot get out).
An alternative approach, which also works with an unvented system (one that has a sealed expansion vessel instead of a header tank), is to freeze the pipe just below the radiator valve. Aerosol kits for doing this are available for under £10. For example, look HERE.
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