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.
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.
Depending on the location and how easy the pipe is to work on, you might be able to do it "live"...
Make sure the system is off and cool. If its a vented system then stick bungs into the F7E pipe out the bottom of the header tank, and also the vent pipe. If its a pressurised system then drain off a few litres to drop the pressure to "not pressurised". Shut off the existing bypass so that you get no or as little flow as possible through it.
Have a 22mm service valve ready with its back nut taken off, loosen the existing one, while keeping the fitting pushed against the olive. The in a quick motion, pull the joint apart and then slap the valve on, and tighten quickly. Having a spare hand available to stick their thumb over the end of the bypass might be handy. Repeat for the other end. You now have a couple of valves you can attach to the new bypass at your leisure.
Have some old towels wrapped about to catch any spillage.
IME you can normally end up spilling less than a half cup full of water.
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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