Leaking CH System

[Rob Summers]

Not found this in the FAQ and various searches have only come up with incomplete information so here goes....

There is a leak a few centimetres below a radiator valve and my plan to repair is this (we have a sealed system btw and the pipe concerned is narrow-bore):

1. Screw the radiator valve fully shut
2. Cut the pipe below the level of the floorboards and quickly jam on a suitable pushfit/speedfit stop-c*ck (or similar) that's closed.
3. Then at leisure replace the dodgy section of pipe with new pipe.

Is 2 likely to be problematic and should I get some freezing spray also? Or am I just likely to lose a little bit of water?

Or is the whole process flawed? ;)

Thanks

Rob

[Dave]

I would de-pressurise the system first - only takes a couple of minutes and may save you from getting very wet! If you do this you can do the whole job in 15 mins or so, including replacing the leaking pipe.

BTW, are you sure it IS the pipe that's leaking, rather than water running down the pipe from a leaking valve or olive?

Dave

[Ben Blaukopf]

a) It will spray water out while you're cutting it b) Can you get pushfit microbore? c) Pushfit needs (in theory) the pipe to be deburred before putting the fitting on d) You might need to put the stop-c*ck on open, given the system is sealed. In any event, an open stop-c*ck will help direct the water flow.

I'd use a compression fitting, and I'd drain enough water out to depressurise the system first (i.e. don't fully drain out, just drain until the pressure gauge hits zero).

Ben

[Rob Summers]

Sounds good. I now need to find out where to depressurise the system I guess it's the pressure vessel in the boiler (it's a glow-worm sxi) that needs fiddling with. (Will check the sealed-system FAQ)

Yup, the pipe is kinked and I dislodged some limescale while trying to patch it up awaiting a proper repair and the limescale had done a reasonable job of healing the problem..... it's much worse now! :(

Thanks

Rob

[Dave]

... snipped

There may be a dedicated drain point, you may be be able to de-pressurise via the filling loop connection or there may be a drain point on a rad valve somewhere. The amount of water to drain will depend('ish) on the size of the expansion vessel; our 30SXi has an 8 litre internal expansion vessel.

Dave

[Ian Stirling]

I've in the past done:

1...

1. Clamp the pipe absolutely flat, over a distance of 3cm or so.

1. Disconnect from radiator, and fold pipe over, before clamping again.
2. Cut end of pipe.
3. Apply flux, and heat below join, so the pipe fills with steam.
4. Apply solder to the flattened end of the pipe.

It actually worked, but is a bodge. With several more folding over steps, and enough force applied, that alone should work.

[Ed Sirett]

You may find that turning the boiler flow/return isolators is easier and simpler than depressurising. You then need only to remove a small amount of water to depressure the rest of the system (unless there is a lot of air somewhere). Watch out if there are any other auto-vents outside of the boiler to catch you out.

Make sure you have the right size of speedfit fitting. Clean the pipe before cutting it. Put a towel under anyway you won't stop every last drop.

[Rob Summers]

Thanks for all your input. I think I know what to do....

.... and on Saturday will find out if I can.

Rob