replacing rad

[finks]

hi all
i have a combi boiler and want to change the rad in the downstairs toilet,but need to adjust pipe work for new rad to fit.
is it possible to switch boiler off,cut pipes and fit iso valves,without draining system, then complete conections in my own time,will water loss be uncontrollable or can finger pressure contain water flow until iso valve is on
is it ok to fit iso valve on central heating system?
any advice
many thanks

 

[BazThePipeman]

If you want to change pipework then do it properly and drain the system.

Perish the thought that you go ahead with water in the system you're going to have to remove your finger from the end of the pipework in order to screw install valves and water is going to come out at a very fast rate.

I personally dont know of any CH system where Isolation Valves have and not sure if this contravenes any regs anyways.

Suppose you could use a pipe freezing kit but I would suggest the drain down.

 

[ChrisR]

No need to drain with a sealed system
Shut the auto air vent cap, release the pressue from a drain cock until the water stops, shut the drain cock , and the rad valve, and get on with it. Only one open end, so you only need a towel.
Don't use cheapo iso valves, they always leak through the stem.
Peglers Full Fow ballvalves (Screwfix) are good, if a bit big. You can remove the handle.

 

[finks]

many thanks,
option 2 did the job nicely.