40mm Pipe to 86mm Cast Iron

4 Sep 2018
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United Kingdom
I have an old style property. The gutters, sinks and baths/shower all connect together in a 86mm stack. The Toilet connects into a 100mm stack. I need to run a new plastic 40mm shower drain but I cant find anyway to contact it to the 86mm cast iron stack.

Does anyone have any ideas?
I'm surprised I cant seem to find a solution. Looking around my neighbourhood its all cast iron.

I got a McAlpine Mechanical Pipe Boss Connector as I read somewhere it was good for fitting to cast iron. The instructions say it will do 110mm and 82mm. It looks way too big to handle 82mm so I don't really want to drill the hole if it wont work.
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I did look at those before but there for condensate discharge only :(
Why do you think it makes a difference? Answer - it doesn't. You shouldn't actually discharge condensate into a cast stack anyway as it causes corrosion over time. They'll be fine for your needs
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It looks like I got a 110mm by mistake. I didn't realize there were difference sizes. The instructions gave the impression there was one universal size to fit both 110mm and 82mm stacks.

I've ordered the 82mm. Hopefully that will work with the 86mm cast iron. (its 86mm measuring on the outside with paint on).
BossCast is the one - bottom of page JC linked to. If it doesn't seal, come back here and learn how to make a hemp grommet ( to go on the outside of pipe ) under the fitting flange;)
Plastic 82mm strap boss's are available but to ensure a watertight seal some onsite intervention is required as per Nigel F.

russ8585,is there any other termination available for your new 40mm drain feed :?:
Only have the 86mm and the 100mm cast iron pipes.

Ive managed to drill a 57mm hole in the 86mm pipe so Im hoping the McAlpine Mechanical Pipe Boss Connector 82mm will work with some silicone and cable ties.

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