cjwbristol Posted November 23, 2020 Share Posted November 23, 2020 Hi All, Recently bought a house and having not much spare cash i'm doing a few odd jobs as diy. The first of which includes swapping out the old copper and iron mains water supply pipe to the house for 32mm MDPE, the only doubt i have is how to reduce from the 32mm MDPE to the internal 15mm copper. At the moment the original stop tap is under the main stairs but as i have a basement with easy access my thoughts are using a 32mm straight stop tap in the basement (jg speed fit already bought) then run some of the cutoff MDPE 32mm to under the stairs (about .5m) then use a 32x22mm reducer into 22mm pipe and then use a 22x15x15 tee to connect to the existing copper pipe with a drain valve coming off the additional tee connect. Is this the correct/best/easiest way? Any other ideas or comments welcome. Thanks! Link to comment Share on other sites More sharing options...
PeterW Posted November 23, 2020 Share Posted November 23, 2020 Welcome ..! First question is why 32mm ..?? Normal connection is 25mm unless it is a very big house, and you have 15mm inside so not really getting the benefit of anything larger. Secondly, where is the water meter ..? Have your water supplier changed their end to MDPE..? They own up to the meter (or isolator if there is no meter) so you can only change what is after that. Ideally you need to have as few elbows as possibly and a tee would count as that - it may be better to replace the 15mm from the old stop tap downward with Hep2O and then try and get a long sweep of a bend through the floor and into the cellar. If you already have the 32mm then I would just use a 32mm to 1/2” male adapter (Pipestock) and then fit a Hep2O 15x1/2 onto this. You can put a tee with a drain cock in if you want to but I assume there is one just above the current stop cock under the stairs ..? 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted November 24, 2020 Share Posted November 24, 2020 i always have 32mm connection, who doesn't want more pressure, and its same price to supply. The water ring is in 22mm with short 15mm spurs to the taps. Noticeably better when shower(s) are being used and a bog is flushed/washing machine on etc. Just have a to re-train moron plumbers out of using 15mm for everything as it saves them 50 quid on the whole build. 1 Link to comment Share on other sites More sharing options...
PeterW Posted November 24, 2020 Share Posted November 24, 2020 4 hours ago, Dave Jones said: i always have 32mm connection, who doesn't want more pressure, and its same price to supply. The water ring is in 22mm with short 15mm spurs to the taps. Noticeably better when shower(s) are being used and a bog is flushed/washing machine on etc. Just have a to re-train moron plumbers out of using 15mm for everything as it saves them 50 quid on the whole build. You don’t get more pressure with increased diameter, it is an inverse proportion. What you may get is increase flow, which means you can run more high flow outlets at once for a given pressure. Using a 22mm “ring” doesn’t help and is poor design - also doesn’t help when you are balancing mains hot and cold outlets such as mixer taps and it’s much better to use dedicated circuits for toilets and outside taps so they don’t affect your shower flows. Link to comment Share on other sites More sharing options...
Dave Jones Posted November 24, 2020 Share Posted November 24, 2020 i disagree, separate rings are pointless. It's all T'd of the same main. All I can tell you is 22mm ring pressure = good. 15mm ring pressure = bad. Link to comment Share on other sites More sharing options...
dpmiller Posted November 25, 2020 Share Posted November 25, 2020 please explain how pipe size affects pressure? Unless of course you mean dynamic pressure, the reduced pressure caused by a restriction to flow? Link to comment Share on other sites More sharing options...
Dave Jones Posted November 25, 2020 Share Posted November 25, 2020 14 minutes ago, dpmiller said: please explain how pipe size affects pressure? Unless of course you mean dynamic pressure, the reduced pressure caused by a restriction to flow? If your being that pedantric of course it doesnt it effects flow. The point being bigger = better. That better for you ? Link to comment Share on other sites More sharing options...
dpmiller Posted November 25, 2020 Share Posted November 25, 2020 No, because bigger is pointless and redundant unless required. I've nearly a kilometre of 32mm MDPE between the Toby and the house.This steps to 22mm as a rising main but only the showers and ouside tap are 15mm, everything else has plenty of *flow* using 10mm. Link to comment Share on other sites More sharing options...
Dave Jones Posted November 25, 2020 Share Posted November 25, 2020 than run it all in 10mm and save a fortune ? Link to comment Share on other sites More sharing options...
dpmiller Posted November 25, 2020 Share Posted November 25, 2020 /not sure if joking, or really don't understand flow... Link to comment Share on other sites More sharing options...
PeterW Posted November 25, 2020 Share Posted November 25, 2020 (edited) 5 minutes ago, Dave Jones said: than run it all in 10mm and save a fortune ? I do... basins, WCs, utility room are all in 10mm, shower and bath is 15mm as is kitchen tap, dishwasher is 10mm spur from this. Shower is 12l/min flow rainfall head, taps all have the correct flow restrictors to meet water regs use. Edited November 25, 2020 by PeterW Flows Link to comment Share on other sites More sharing options...
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