hello all, i need to change a rad in the bathroom ( upstairs ) also will change a knackered TRV can i avoid draining the system to do this job if i just turn off all the feed valves from tanks etc ? i dont know what system it is as not my house just want to do ASAP thank you helpers P M
avoid draining
- Thread starter poshman
- Start date
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Yes you could change the rad without draining all the system down.
As you suggest if you have a valve on the supply from the tank you would close that down.
Turn off all the rad valves on all the upstairs.
With a bowl underneath the rad which is being replaced crack open the union and allow to drain. Remembering to open the air bleed to force the water out.
Remove the rad and then the only water left is in the upstairs pipes.
Drain this through one of the rad valves into your bowl.
Only thing to remember is that the last bit of water from the rad is likely to be black and will stain your carpet or whatever.
Turn the rad upside down to carry downstairs.
Make sure the pump is turned off while you do this and dont use the boiler whilst the job is being done.
wemyss
As you suggest if you have a valve on the supply from the tank you would close that down.
Turn off all the rad valves on all the upstairs.
With a bowl underneath the rad which is being replaced crack open the union and allow to drain. Remembering to open the air bleed to force the water out.
Remove the rad and then the only water left is in the upstairs pipes.
Drain this through one of the rad valves into your bowl.
Only thing to remember is that the last bit of water from the rad is likely to be black and will stain your carpet or whatever.
Turn the rad upside down to carry downstairs.
Make sure the pump is turned off while you do this and dont use the boiler whilst the job is being done.
wemyss
thank you for alll that information, just got to motivate myself now 
Should perhaps add that the above is for a conventional system and would not include a Combi boiler or a pressurised system.
The tank to isolate in the roof space provided it is a conventional system would be the small one only.
If there is no isolating valve on the feed out of it you would have to tie the ball valve up and you would still have the water in that tank to get out.
Would suggest bailing most of it out. Or perhaps there is a drain valve on the upstairs pipework.
wemyss
The tank to isolate in the roof space provided it is a conventional system would be the small one only.
If there is no isolating valve on the feed out of it you would have to tie the ball valve up and you would still have the water in that tank to get out.
Would suggest bailing most of it out. Or perhaps there is a drain valve on the upstairs pipework.
wemyss
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JPC said:
cuppa good idea
drain off valve what from the downstairs rad cheers P MYou can turn off the feed valve from the tank, but they are rarely fitted. You also need to plug the vent pipe, or slide a push-fit stop end over it. If you don't have a feed valve from the tank, you will have to fit a bung in the pipe from inside the tank. Before you let water into the system again, you should clean the tank completly.
Rubber bungs.
You can get a pair of conical rubber bungs from the plumbing shop. Put one in the feed pipe from the little tank in the loft, and one on the vent pipe that curls over it.
Your system is now sealed. Think of holding your thumb on one end of a pipe full of water, to stop it running out of the other.
Open the drain valve and only a cupful will come out, because no air can get into the top of the system to replace water escaping at the bottom.
You can undo and remove your faulty TRV, and as long as the rad valve at the other end of your rad is tight shut, there will be no flood.
Warning! Don't open or remove more than one thing at a time, or air will get in through one opening, and water will squirt out of the other.
(Edited to say, Oilman got it before me)
You can get a pair of conical rubber bungs from the plumbing shop. Put one in the feed pipe from the little tank in the loft, and one on the vent pipe that curls over it.
Your system is now sealed. Think of holding your thumb on one end of a pipe full of water, to stop it running out of the other.
Open the drain valve and only a cupful will come out, because no air can get into the top of the system to replace water escaping at the bottom.
You can undo and remove your faulty TRV, and as long as the rad valve at the other end of your rad is tight shut, there will be no flood.
Warning! Don't open or remove more than one thing at a time, or air will get in through one opening, and water will squirt out of the other.
(Edited to say, Oilman got it before me)
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