Changing a Pipe in Central Heating System All aspects of plumbing questions and answers, help, tips and information

[omits]

I have two pipes going from 1st to ground floor. I need to take out a section in each (copper) and put in plastic ch pipe thus removing a kink in both pipes. Can I successfully use one of those vacuum kits where one blocks the overflow and outlet of the feed tank in the loft? I want to make sure before I try this so maybe someone has done this. Thanks.

[plumbbob]

I've been using these kits regularly for over five years now and how found in a majority of instances ther remove the necessity of draining down. The problem is, I have found no way of gauging beforehand how successful they will be. Sometimes the flow stops after about a pint and other times you wonder what's the point. Occasionally the flow won't stop, but it slows enough to allow for a compression coupling.

Here are a few tips I would offer.

1. Don't use a bung in the expansion pipe. Use a Speedfit end cap.
2. Don't work on the flow and return together. Do each at a time. (Breaks the vacuum otherwise)
3. The lower down you are on the system the less likely it will work.
4. Be prepared for a large unexpected flow of water. On one job I thought everything was under control and suddenly...... Luckily I had a thumb and a mate to empty the buckets.

Basically, you are in the lap of the gods.

Have you considered freezing the pipes?

[omits]

Thanks for replying, I'll try the vacuum method with your advice points. I have to basically swap over some plastic push on fittings. I will remove a lot of the feed tank water and shut off all radiators and have some stop ends in my pocket ready!

[plumbbob]

There is no need to empty the header tank, it is blocked off anyway.

Just release the pressure in the system before you separate the pipes. Undo a drain vale close to where you are working. This is going to be the trick bit, undoing the first connection. You could get a good spray of water.

I usually just go for it because it is only water at the end of the day but that's just me.... Bear in mind it could be Dirty water. Black water + beige carpets = four letter words.