What size waste for two bathroom basins into one waste?

[wellerman]

Installing two basins in my bathroom refurb.

I was going to link two seperate basin wastes into one waste. Can I keep the waste at 32mm for its entirity of do I need to go to 40mm where they meet?

The total waste run should be approx 2m straight across the floor to the soil pipe.

 

[Bahco]

Max is 1.7 for 32 mm but if you fit an anti vac trap on 1 basin you will be ok.

 

[wellerman]

That's great. Thanks

 

[neds]

You could also use a running trap or an in-line trap.

 

[wellerman]

"a running trap or an in-line trap"

What are they?

 

[omegaman]

I would use 40mm where they meet.

inline trap
http://www.google.co.uk/products?q=...esult_group&ct=title&resnum=1&ved=0CBEQrQQwAA

running trap:
http://www.google.co.uk/products?q=...esult_group&ct=title&resnum=3&ved=0CBkQrQQwAg

 

[wellerman]

I intended to run the waste pipe down the stud wall and then under the floor so there will be no access to these traps.

If each basin has it's own trap anyway, do I need to fit another one further down the line?

 

[Richard C]

I intended to run the waste pipe down the stud wall and then under the floor so there will be no access to these traps.

You can't locate traps under the floor where there will be no access it won't comply with Building Regs. either.

I would run 40mm from the 2nd basin as well.

 

[wellerman]

I thought that about the access - so why do I need to fit a running trap or alternative if the basins already have a trap each?

 

[seco services]

you don't.

 

[wellerman]

Talk about confuse me!

Thanks all. I'll use 40mm and just join them up as I intended.

 

[Nige F]

Don`t use traps -use Hep V O waste valves

 

[wellerman]

Got two wall mounted basins with nice chrome wastes underneath so won't be needing any more traps or waste valves

 

[Richard C]

That brings you back full circle; the nice chrome traps won’t vent & if you connect the 2 basins into one waste run you may suffer siphoning of one or other basin trap, smells & gurgling noises. 2m unvented is fairly short & if you run in 40mm right the way through you may get away with it but then you may not.

 

[wellerman]

Right then - so I have two wall mounted basins, both with own traps, and then I have a running waste valve in each waste pipe prior to them linking up into one pipe to discharge?

Thing is I want all the pipework hidden in the stud wall. How do I get round this?