Steel to copper pipe - plastic pushfit in CH system

3 Jul 2010
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United Kingdom
Hi there

We have some steel pipework that feeds the radiators in our lounge. I have just replaced the radiators with some slightly smaller ones so i have had a chap come round to adjust the pipework to accomodate the smaller radiators.

What he has proposed is to join the old steel pipe to some new copper pipe that will connect to the radiator. However, as he cant solder steel to copper he is proposing using a plastic push fit connector.

Do people think that this will be ok? i am slightly concerned as obviously the pipes will have water pumping around them (whilst we have a traditional boiler i.e not combi.. it is a closed pressurised system). Also, can i add inhibitor or could this damage the plastic/connector in anyway? Would a metal pushfit be a better idea?

Are there any alternatives?

Thanks for your help in advance.
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Steel, copper AND plastic!? Sounds hideous to me. I don't see how he's going to get a pushfit onto steel either, and even if he does it probably won't hold for very long as it's not designed for it.

If it's the old threaded steel then it's quite easy to wind it out of a fitting then adapt from the resultant threaded fitting to copper.
Are there any alternatives?

Dismantle the steel pipe at a threaded fitting, get a bronze adaptor fitting which will connect the BSP thread to a copper compression fitting. If there's no convenient threaded connector, any competent plumber could cut a thread on an end of the steel pipe. that's the proper way to do it.

I don't know of any push-fit connectors suitable for steel, but someone will post info if such things are available. The steel gripper teeth usually won't grip hard pipe.
Yes there are transitional fittings for steel, but I sure as hell wouldn't use one on heating. :rolleyes:

Is August cowboy month. :LOL:
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Brass as onetap has stated. You dont want steel and copper meeting directly, obviously.
not sure if they are steel or stainless steel tbh. Cant remember what the guy said.

It sounds like some sort of threaded dielectric union might be the best way to go then. I have also seen these that claim to be suitable for copper and stainless steel.

Thanks for all the replies so far.

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