Can a DIY'er replace a radiator valve without draining down?

2 Dec 2004
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United Kingdom
Hands up, I've caused a problem for myself.
When changing a rad I snapped off the tip of the lockshield valve when it seized shut. I now need to replace the radiator valve preferably without draining the sealed combi system. Can it be done?

I've thought of pipe freezing, but can't find a kit and have no idea how much it costs.
I've thought of removing the valve top and replacing it very quickly?
I've also thought of fitting a push fit pipe isolator inline with the valve to give me time to change the valve, but I have no idea if any of these (or other) ideas are viable.

Ideas please, hopefully one without making to much of a mess.

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Turn all your other rads off and drain down. Rebalance and inhibit your system :D
Just drop the pressure in the system . You can swap the valve without draining down if you do it quickly, just have plenty of towels just incase.
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Cheers guys. I took your advise and added a £23 domestic pipe freezing kit just in case. I managed to get away with only enough spillage to take up 2 sheets of kitchen roll :)

My only problem now is that after changing the rads I now have a rushing water type noise coming from the pipes which run down the wall from the upstairs boiler to the downstairs kitchen rad. I can only think of giving it a couple of weeks before bleeding the system again in case any air is in the pipework?
I did, but the paperwork that came with the new rads said to bleed again after 2-3 weeks, probably in case fitting the new rad creates an airlock in the system?
That just means bleed again in a few weeks anyway, you can bleed at anytime if you think theres air in, if its topped up with inhibiter and no leaks it should be fine.
Yeah I filled the largest rad with 1/2 litre of inhibitor to be on the safe side, but I'm concerned as to what the rushing water in the pipe coild be caused by?

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