JohnMartin68 Posted March 3 Share Posted March 3 Photo shows a 90 elbow where the incoming mains supply comes up from underground. At the bottom of the photo you can see the incoming mains in black plastic. On the left it reduces to 15mm copper using some sort of bush, going towards the stopcock. Since all the copper needs to be re-routed, I decided I will do some of the main runs (e.g. to outside tap) in 22mm to get a bit of extra flow. Seems simple enough to just remove the bush and replace with 22mm pipe, but are there any pitfalls I should be aware of? For example: - Could the bush be non-removable somehow, in which case I would need to disconnect the elbow at the plastic? - I couldn't quite read the markings on the elbow but looks a bit like 7/8 or something. The marking on the bush flange is definitely 22mm though. Are the metric and imperial interchangeable for compression fittings? Link to comment Share on other sites More sharing options...
sharpener Posted March 3 Share Posted March 3 How old do you believe this to be? Modern plastic pipe is blue MDPE and 20 or 25mm O/D, you need different fittings for it. I would try not to disturb the plastic pipe connection. AFAIR 1/2 inch and 15mm pipe are interchangeable for all practical purposes, but 3/4 in and 22mm are not quite and you certainly need different Yorkshire fittings for them, maybe also a special olive like you need for 3/8 to 10mm. But if the bush is marked 22 then it's a reasonable assumption that 22mm pipe would be OK in its place. I doubt it is non-removable but even if so it will probably be jammed on the pipe anyway. So at worst you would need a spare cap nut and new olive. Most compression fittings have standard BS pipe threads, but I have in the past come across some ?Pegler? with finer threads, the nuts usually have 8 flats though not the six which you have got. Dribble some easing oil around it the night before. Clean the nut and fitting with fine steel wool but don't leave any debris behind. 1 Link to comment Share on other sites More sharing options...
Alan Ambrose Posted March 3 Share Posted March 3 (edited) Check you can shut off external to your property first? Any chance of replacing the black plastic from there with modern mdpe? Rest of your pipework fairly old? Think I might leave well alone otherwise. Edited March 3 by Alan Ambrose Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 Thanks that reassured me a bit. Piping is probably 1970s and you're correct I really don't want to disturb the plastic connection. Will take extra care not to bend the elbow. Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 2 minutes ago, Alan Ambrose said: Check you can shut off external to your property first? Any chance of replacing the black plastic from there with modern mdpe? Rest of your pipework fairly old? Think I might leave well alone otherwise. External shut off works fine I have used it before. No chance of replacing the plastic I would need to dig up about 50m of pipe and it goes underneath the building. Piping downstream of elbow is all being replaced. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted March 3 Share Posted March 3 Think I might tee of then v carefully after that existing fitting or even better after the stopcock. I’m concerned the black pipe might be brittle due to age. Have any idea how old it is? It could be black mdpe. Don’t suppose you have some calipers to check its size? Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 (edited) I took a photo from underneath, seems to be the same size as the elbow or a tad smaller. Do you think there's a danger of damaging it when trying to loosen the downstream nut (at the copper, not the plastic)? My technique is to use one spanner around the body of the elbow and one around the hex and squeeze the handles together with one hand if possible. Edit: forgot to say the stopcock is knackered and needs to be moved slightly anyway. But mainly I want to have a 22mm run all the way to the outside tap. It probably isn't going to make much difference if I swage up from 15 to 22 just after this elbow though, so if there's a risk of damaging the plastic I would play it safe. Edited March 3 by JohnMartin68 Link to comment Share on other sites More sharing options...
SimonD Posted March 3 Share Posted March 3 Can't be entirely sure but it looks like they've used and compression reducing coupling like this https://www.bes.co.uk/22-mm-x-15-mm-reducing-set-17738/ In that case it should be fairly straight forwards to remove the coupling and 15mm to replace with something else. In a previous house we had black plastic mains supply too. Link to comment Share on other sites More sharing options...
sharpener Posted March 3 Share Posted March 3 24 minutes ago, JohnMartin68 said: But mainly I want to have a 22mm run all the way to the outside tap. I would have thought unless a very long run that would be the least of the probs, usually it is the bath tap that needs the best flow - and for the hot the supply to the h.w. tank, do you have an unvented/pressurised setup (or planning to fit one)? Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 Not really for the indoor plumbing, I want to debottleneck the flow to the outside tap as much as possible for the benefits this may have. Washing, watering and a few other niche uses that aren't so common. I will probably run 22mm to the bath/boiler as well but that's just opportunism rather than any practical benefit. Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 (edited) Deleted see below. Edited March 3 by JohnMartin68 Link to comment Share on other sites More sharing options...
JohnMartin68 Posted March 3 Author Share Posted March 3 (edited) 29 minutes ago, SimonD said: Can't be entirely sure but it looks like they've used and compression reducing coupling like this https://www.bes.co.uk/22-mm-x-15-mm-reducing-set-17738/ In that case it should be fairly straight forwards to remove the coupling and 15mm to replace with something else. In a previous house we had black plastic mains supply too. SimonD are you referring to the connection with the copper or the plastic? Can't see anything like this on the plastic it looks like it is coupled direct to the elbow? Edited March 3 by JohnMartin68 Link to comment Share on other sites More sharing options...
SimonD Posted March 3 Share Posted March 3 21 minutes ago, JohnMartin68 said: SimonD are you referring to the connection with the copper or the plastic? Can't see anything like this on the plastic it looks like it is coupled direct to the elbow? The copper Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 3 Share Posted March 3 Panic ye' not. https://www.plumbingsuperstore.co.uk/product/internal-reducing-set-35mm-x-15mm.html?gad_source=1&gclid=CjwKCAiA3JCvBhA8EiwA4kujZiTSwgQH7eTA1H_Fsvtoka306J14zPpsT6Ocg-8yMTrcwhMMv8bUzRoCO_YQAvD_BwE It's just an internal reducing set. You can replace it with a 10p 22mm olive and insert 22mm pipe straight in. Link to comment Share on other sites More sharing options...
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