DIY Doctor

Cutting into a central heating system

Postby Barry Bunsen » Mon Oct 11, 2010 6:22 pm


I wish to tee into the 10mm flow and return pipes of an open vent central heating system. I intend to shorten the supply route to a radiator that will not heat up (Ive tried unsuccessfully to flush the existing supply route , turning up the pump, and turning off the other radiators to get it going).
The radiator is downstairs in a 2 storey house with the f&e tank in the loft.

My question is would I be able to bung the f&e tank to do this or is it a bit risky? If not are the aerosol freeze sprays any good and how long would they give me? Or should i just go for a traditional drain down?

Any comments would be appreciated.
Barry Bunsen
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Simply Build It

Postby htg engineer » Tue Oct 12, 2010 5:32 pm

If a radiator is not heating shortening the pipe run probably wont help - it's either airlocked or there's a blockage - quite common to get blockage at radiator valve or manifold.

If you're thinking of teeing into a 10mm pipe that is feeding another radiator - don't - it will not work - one radiator will starve the other and you'll have the same problems as you're having now.

Does the problem radiator have it's own 10mm flow and return tee'd into 22mm or connected to manifold ? if it shares it's 10mm flow and return with another radiator - then there's the problem.

htg engineer
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Postby Barry Bunsen » Wed Oct 13, 2010 11:12 am

Thanks htg. That seems very good advice. I had my doubts it would work. I think there is a partial blockage in the return pipe from the rad and I hoped replacing and shortening the flow and return pipes might liven things up. However teeing into other 10mm pipework is probably not a good idea. Its a big rad as well. One of those floor to ceiling 'Tubular Bells' types. Unfortunately all the 10mm pipes in the house disappear straight into the walls and dont surface again until you see 22mm pipes by the hot water cylinder. I suppose some floorboards will have to come up.
Thanks again.
Barry Bunsen
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