You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Am I right in thinking its as simple as turning off both valves, turning off the heating system, bleed the radiator, drain the radiator, and then quickly swap the valves round? Can't help but think that water will come gushing out once I take the valve off - will this only happen if the system is pressurised, i.e. as ts only a small radiator that is being drained, I may need to bleed another? If the pressure gauge on the boiler drops to zero, will that mean the amount of water coming out of the pipes will be minimal?
I always thought you could just unscrew the old one and screw the new one straight on?
You just need to make sure the replacement is compatible?
Watching with interest, to see how wrong I am!!!
I would drain below the height of the rad pipework
are you replacing the whole valve, or just the thermostatic bit?
...then quickly swap the valves round?
By "valve" do you mean the metal valve body or the plastic thermostatic head (or both)?
Removing the valve body will leak (probably dirty) water as soon as you remove it from either the pipe or the rad so the system will need a partial drain down.
The thermostatic head shouldn't leak if removed, screw the replacement to fully hot before refitting it
X with jam-bo
Replacing the valve or the thermostat? You can just replace the actuator top part without taking the 'valve' apart, they usually just unscrew or unclip from the valve.
Replacing the valve you would need to drain the system to below that level, anything else would get messy unless you were very quick and had lots of towels to hand.
If you're draining the system, close both valves on all radiators before you drain. Then you've only the pipe work to drain, not the contents of all the rads as well.
Then you’ve only the pipe work to drain, not the contents of all the rads as well.
Except of course on the rad where you are changing the valve, which you want to drain.
An alternative is to use a pipe freezing kit on the section of pipe below the valve, if there is space. It’s then a matter of cost of the kit vs hassle in draining the system.
This video
at 7:20 he’s basically draining the system via the bleed valve?
I’m replacing a radiator and a non TRV straight connector for an elbow valve. Normally end up draining the entire system but this looks like it’s not necessary. Granted there is a little water leaking, and he’s quick, but I’d thought the water loss would be substantial. It’s a combo boiler with the valve to be replaced upstairs. If I close the valves on all the upstairs rads, drain the radiator, Will there be any pressure in the system?
If it's a combi boiler, they normally have a small pressure vessel built-in to maintain system pressure (at about 1 bar). This would need to be bled off or the pipework side of the TRV will still be pressurized. Are there shut-off valves between the boiler and the pipework at the boiler?
I don’t know of any
...at 7:20 he’s basically draining the system via the bleed valve?
IANAP. He's checking that the bungs have sealed the system, but that tank won't exist in a combi. A combi system will be pressurised, which is what dafydd is saying
The freezing kits do work... Mostly. best do a dry run with all the tools laid out.
The last one I did deposited a slug of use and a large quantity of water down my armpit and into my sleeve before I got the thumb over the end of the pipe!
Removable press fit ends are your friend if you decide you wish you hadn't started.