Hi guys, new to this forum and hopefully someone can help, I’m putting in a new shower which will be run off a combi, (no pump in between), my question is can I use 32mm waste, it will only run a maximum of 50cm into a soil pipe, it’s impossible to go up to 40mm because of lack of room, thanks in advance.
Shower waist size
- Thread starter Hello123
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Ok, to put it another way will the water drain away quick enough with the above spec?
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32mm? Maybe, maybe not. Plumbing is difficult at times, you need to use 40mm as a minimum.
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You won't get a shower trap @ 32mm so you would have to reduce the pipe in the first place.
32mm probably won't flow well given the height of the shower tray, it may also suffer from back pressure/vacuum especially if you have a high flow mains shower fed from a combi. The shower waste pipe needs to flow at least the same amount as the shower can deliver.
What is the lack of space and why you cant use 40mm?
32mm probably won't flow well given the height of the shower tray, it may also suffer from back pressure/vacuum especially if you have a high flow mains shower fed from a combi. The shower waste pipe needs to flow at least the same amount as the shower can deliver.
What is the lack of space and why you cant use 40mm?
Yes I’m aware that I have to reduce down from the trap to 32mm, the reason for lack of space is I’m running it between some steel work, 40mm is definitely a no no, I thought that maybe as it’s only a 50cm length of run that it wouldn’t be a problem?
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It could be a problem, and a big one depending on the access.
It's not really whether a 500mm run @32mm would be an issue or not, it's more, can a 32mm diameter pipe flow enough water to allow an 'x' amount of water a min without filling the pipe and then causing a possible vacuum, the minute the pipe if filled the flow will slow down as it has a force to overcome. A shower isn't that high up so the 'head' or pressure of the water running out of the waste pipe is very little so any restriction it comes across will have an impact on flow.
I have never used 32mm on a shower waste over any distance though I have been called out to problem showers where the pipe has been reduced to 32mm and it has caused problems. I guess if you have no other option then it must be 32mm but I don't believe any of the pros on here would be able to give you any guarantees that it wouldn't have issues, especially over the longer term, on the other hand it may work fine.
It needs tested by setting up the shower tray with the waste run and see how it performs before the final fit.
For what it is worth
The constraints in my cottage left me no option for the shower drainage but to use 32mm over a straight 3 metre run that has very little fall.
Shower is fed with hot and cold both at mains pressure ( heated by a shower coil in hot water cylinder ) so flow is high
Tray and integral waste trap had to be a bespoke fabrication.
No problems ( so far ). Water has never over flowed out of the tray.
The constraints in my cottage left me no option for the shower drainage but to use 32mm over a straight 3 metre run that has very little fall.
Shower is fed with hot and cold both at mains pressure ( heated by a shower coil in hot water cylinder ) so flow is high
Tray and integral waste trap had to be a bespoke fabrication.
No problems ( so far ). Water has never over flowed out of the tray.
By bespoke fabrication how different was it from a standard shallow shower trap?
This is the original working sketch of the tray and trap. Not to scale. The ABS bar ( grey ) is 30mm thick
The inverted U in the trap has supports to keep it's top level with the surface of the tray.
All the tray is solvent welded. The wall sheets are not welded to the tray due to the problem of the ABS expanding when warmed,
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