If there is a substance in the water, then its freezing point is going to be
lower.
Also you might need to be very quick to get it done, no room for problems
once the pipe is cut.
Brian

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"Davidm" wrote in message
...
On Sat, 16 Feb 2019 17:11:08 +0000, Clive Arthur
wrote:

I want to replace a bypass valve in the central heating. It's easily
accessible and uses 22mm copper pipe with compression fittings.

I don't want the bother of draining, refilling, bleeding, adding
inhibitor etc, so how well does freezing work? I've never done it or
even seen it done, but £17 from Screwfix seems reasonable if it works.


Cheers
You might find that you need 2 cans of freezer for 2 sections of 22mm
pipe (ie. either side of the bypass valve). There's a user comment to
this effect on the Screwfix page, but also comments that it works ok.
Let the system cool right down before use.