New bathroom waste advice please

[covert]

So I'm installing a new bath. Vanity unit and loo in February and need advice on the waste for the vanity unit please.

It's a stand alone oak unit with square basin on top , so the trap will be in the top half of the vanity unit
Problem I have is there are shelves inside so the trap will have to be shallow , no problem as I saw one of these

Shallow Bottle Trap 38mm x Seal x 40mm

The waste is a 40mm unit so this will fit but I'm struggling to find anything to fit in this like a 90 degree elbow and go down to the waste pipe ,

Waste pipe is shared with the bath so thinking of putting in a non return valve as at the moment if I take the plug out of the sink the water come up the waste in the bath,

Hope this makes any kind of sense and thanks for any advice you can give me
Cheers Mark

 

[Best]

You can get 90 degree waste pipe bends, solvent weld or push fit and male to female type (one side same as pipe) also.
Consider also using the type of waste that immediately bends away from the waste fitting and a trap can be fitted at rear.
Take a look at waterless traps - Hep2 o type
Or take a look at this to give you a visual idea, -
Uniwaste™ Waterless Waste Space-Saving Trap for Basins, Baths & Bidets

 

[neilrj]

You sure you don't need the 32mm size for a basin (#20705)? Then use a pushfit street elbow this will be as tight a bend as you could want - 40757 (32mm). If it really is the larger size then use 51088 street elbow and an 88583 reducer to 32mm.

 

[covert]

Yup definitely 40mm outlet

 

[Ric2013]

Normally 1.25" or 1.5" BSP thread on a waste for nominal 32/40mm pipes to trap. This unthreaded waste is new to me, and possibly the manufacturer is expecting you to use its own brand of trap?

38mm seal only considered acceptable going into a hopper, not if connecting to soil and vent pipe, and not at all on a basin.

I wouldn't share a waste with a bath at all unless there really is no alternative, and, yes, if you must, your idea of a non-return valve is not a bad one, but may end up costing almost as much as a decent professional alternative not requiring said valve. HepVOs seem to be getting expensive, if that's your thought.

If you want to DIY this, I would suggest you have a good read of Approved Document H, section H1. At present I feel you are likely to make it up as you go along and do a job that will never be quite right.

 

[neilrj]

Yup definitely 40mm outlet

View attachment 32382

40mm across the threads is 1 1/4" waste size, it needs 32mm pipe if push fit.

 

[covert]

Apologiesfor the awful pic the waste is threaded so no problem there .
Unfortunately I have no other option but to share the same waste pipe as the bath , luckily it's only me and my partner so the basin and bath won't be used at the same time, thanks for all the help so far folks

 

[Ric2013]

I would never share the waste as my first choice, but in a retrofit, it can be done. You may need to use anti-siphon, resealing, or waterless traps if there are issues with traps being sucked dry. They may be noisy, but they do work, after all.
Now I can see the threads - just!
Worth noting you can buy a knuckle bend adapter that screws straight onto the inlet of a HepVO, so you could put this horizontally under your basin waste and route the pipe away from the shelf.