Dan F Posted February 13, 2021 Share Posted February 13, 2021 What is best practice for diameter for wet-room shower discharge pipes? Our architect has specified 50mm, shower drain has 50mm diameter trap and showersave is 50mm but it seems building regs only requires 40mm and plumber apparently only ever uses 40mm Link to comment Share on other sites More sharing options...
PeterW Posted February 13, 2021 Share Posted February 13, 2021 50mm as a high flow shower can gurgle and stall with 40mm waste. 1 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 13, 2021 Share Posted February 13, 2021 50mm every time. It’s big enough to create an air break over the discharging water / suds, whereas 40mm often won’t discharge anywhere near as free-flowing as with 50mm as the entire bore fills with water / suds and stalls. Makes a huge difference if there is even as little as 1000mm or so of horizontal run. 1 1 Link to comment Share on other sites More sharing options...
Dan F Posted February 13, 2021 Author Share Posted February 13, 2021 (edited) @PeterW @Nickfromwales Thanks. I did talk them into using 50mm, but: - They've used 40mm for bath. - They've connected 50mm pipe from the shower trap to the top of the showersave with what looks like some 40mm pipe and elbows. - They've connected bottom of showersave to SVP, again, with what looks like 40mm pipe and elbows. Will the 40mm not have any real impact if it's only these connections? Or, will they negate the use of 50mm pipe from shower, or even worse create a bottleneck of some sort? I thought I had a photo on my phone.. but seems not, will post one tommorowow.. Edited February 13, 2021 by Dan F Link to comment Share on other sites More sharing options...
PeterW Posted February 13, 2021 Share Posted February 13, 2021 Bath flows don’t need to be quick as they aren’t dealing with constant flow. What diameter is the showersave..? Link to comment Share on other sites More sharing options...
Dan F Posted February 13, 2021 Author Share Posted February 13, 2021 1 minute ago, PeterW said: What diameter is the showersave..? 50mm Link to comment Share on other sites More sharing options...
PeterW Posted February 13, 2021 Share Posted February 13, 2021 I’d ask them to pull the 40 out then and use 50 - shouldn’t take that long and should be done as requested. 2 Link to comment Share on other sites More sharing options...
Dan F Posted February 13, 2021 Author Share Posted February 13, 2021 3 minutes ago, PeterW said: I’d ask them to pull the 40 out then and use 50 - shouldn’t take that long and should be done as requested. Will do. More than "as requested", assume it's also what's correct/expected, especially given shower pipe/showersave are both in 50mm. We actually have one showersave picking up two showers (which may occasionaly be used at the same time), so probably even more important here.. Thanks, 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 13, 2021 Share Posted February 13, 2021 Bath water has a lot of gravity assistance, showers need to have free-flowing discharge as they have next to no gravity to help get things gone. Agree, get them to pull it out and do as the MI’s suggest, even more so if two showers are on one unit Link to comment Share on other sites More sharing options...
Dan F Posted February 13, 2021 Author Share Posted February 13, 2021 1 minute ago, Nickfromwales said: Bath water has a lot of gravity assistance, showers need to have free-flowing discharge as they have next to no gravity to help get things gone. Agree, get them to pull it out and do as the MI’s suggest, even more so if two showers are on one unit Thanks. We are using a local plumber and they are somewhat out of their depth with some of our non-standard requirements: - Silient-PP - 50mm shower drainage - Showersave - MLP - Single central hot manifold next to UVC - 12mm for basins (3 with 12mm hot return) Link to comment Share on other sites More sharing options...
TonyT Posted February 13, 2021 Share Posted February 13, 2021 Agree with others, if they aren’t installing as per your design, tell them to remove and replace or just replace them and deduct monies off their invoice to reflect the incompetence and for plumber 2 to take over. these are the things that will annoy you later. same with the spark installing 16 mm instead of 25mm 1 Link to comment Share on other sites More sharing options...
Dan F Posted February 14, 2021 Author Share Posted February 14, 2021 @Nickfromwales Here you go, this is the one that serves two showers Link to comment Share on other sites More sharing options...
PeterW Posted February 14, 2021 Share Posted February 14, 2021 So why use that crap 40mm solvent weld where 50mm is already fitted ..?? That first elbow will collect crud as the stopper shouldn’t be fitted horizontal as it creates a lip in the elbow. Also, they should all be swept elbows and not 90 degree elbows. I would have done that with 45 degree bends - smooth and fast into the heat recovery unit. Just looks like they used what was on the van Link to comment Share on other sites More sharing options...
Dan F Posted February 14, 2021 Author Share Posted February 14, 2021 4 minutes ago, PeterW said: Just looks like they used what was on the van Exactly! The solvent weld stuff in itself isn't bad is it? Rather, it's just the way they've reduced to 40mm and the 90deg bends, right? This is below: Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 14, 2021 Share Posted February 14, 2021 (edited) ?. Get them to change it! That’s lazy. The 110mm boss will need cutting out too, as they’ve glued in at 40mm Edited February 14, 2021 by Nickfromwales Link to comment Share on other sites More sharing options...
PeterW Posted February 14, 2021 Share Posted February 14, 2021 I don’t get it ..!! A strap boss is 50mm out of the box, you have to buy a reducer to fit 40mm..! Link to comment Share on other sites More sharing options...
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