40mm waste

[ldoodle]

Hiya,

I have a single hole in the wall where the existing bath and basin waste exited through - the basin waste joined into the bath waste under the bath, which then went out the wall.

We have moved the bath to the other side of this hole, so now I need to tee off the 'exit' pipe in both directions, only i'm not sure how best to do it.

A simple (equal or swept) tee would obviously be at the same drop angle as one side of the pipe, which means the other side would be uphill.

I have drawn a very simple diagram showing the route;

View media item 34376
purple = traps
black = pipe
red = equal/swept tee
blue = obtuse bend

Is there a better way?

 

[Richard C]

Presumably the exit to the soil pipe is located at the tee (red)? You cannot use a tee; one waste feed will be directly opposite the other & water from the bath will flow up the basin waste branch & vice versa; connections must be offset. You cannot run a waste pipe uphill either, water will continually lay in the pipe & it’s also a breach of Building Regulations; the maximum length for unvented 40mm waste run is also 3m. Running the washbasin & bath waste into a common waste run will mean constantly pulling the basin (& possibly bath) traps when you use one or the other, you need to fit either an air vent or an anti-siphon trap. You’d be better off making a separate, new connection to the stack, either 200mm above or below the existing connection.

 

[ldoodle]

Yes the exit part of the pipe would be at the tee.

I completely understand what you say about teeing to 2 wastes and I wasn't suggesting to do it that way; it's just the first thing that came into my head!

Just so you know, the waste, when exiting the wall, doesn't drop straight down or boss straight into the stack. It runs horizontally, along with the stack, above the (pitched) kitchen roof about 2m, then joins the vertical stack.

The original route and tees etc were there when we bought the house 5 years ago but have no idea when the bathroom was originally done so regs may have been different; total route upto bossing into stack was probably about 5m. The 40mm waste is already kissing the kitchen roof!

Does a new connection strictly have to be 200mm above or below the existing one? I ask as the existing hole is only 50mm or so above floor level, excluding tiles etc so cannot be lower and 200mm higher would be above the trap resulting in an uphill route anyway. Can't drop the new waste below deck as joists would be in the way and I don't fancy drilling 42mm holes in them!

However could it be run in a 'shotgun' fashion out the wall, i.e. touching the existing pipe? If so I could just make the current hole bigger (instead of drilling a whole new hole) and join to the existing external 40mm wasteand adding an air vent.

 

[Charnwood]

Stick a HepVo valve in each leg.
You will need the pipe-to-pipe adaptor, too.
You will not need to fit traps if you do use the HepVo valves.

http://www.hepvo.com/

 

[Richard C]

Does a new connection strictly have to be 200mm above or below the existing one?

Only if there is a risk of crossflow (with opposing connections) but you are going to be restricted by the size of a boss strap or the boss fitting itself.

I’m having difficulty visualising what you have without a sketch. If the waste branch to the stack runs along the outside of the wall, you could tee directly into that through a new hole in the wall. 6m is way above the maximum for an unvented branch & I’m surprised you haven’t had problems with siphoning & smells in the past.

Stick a HepVo valve in each leg.
You will need the pipe-to-pipe adaptor, too.
You will not need to fit traps if you do use the HepVo valves.

http://www.hepvo.com/

or an anti-siphon trap.

= HepVo

 

[ldoodle]

Thanks guys.

One thought I've just had is to put a new hole in under where the bath will be, past where the trap will be.

That way I could elbow out the wall, run from the basin all the way to this elbow past the bath trap, with a tee along the way accepting the bath trap.

I would then use anti syphon traps? It would then avoid having even more ugly pipes externally as it will all be boxed in internally. Only stumbling block could be the fall from the basin to past the bath - what is the minimum?

 

[ldoodle]

Stick a HepVo valve in each leg.
You will need the pipe-to-pipe adaptor, too.
You will not need to fit traps if you do use the HepVo valves.

http://www.hepvo.com/

Can these valves be placed anywhere along the route? I ask as I have a vanity unit with sink on top so putting a HepVO straight into the basin waste would consume and awful lot of space in the cabinet, so I was thinking of double elbowing out the waste to get flush to the wall, then use one of these.

 

[Charnwood]

= HepVo

Strictly speaking a HepVo valve is not an anti-syphon trap, but will do the job of one allowing water or air in one direction only.

You can get an elbow that fits onto the basin waste and the HepVo valve fits onto that. The valve is then in a horizontal position under the basin, if that would be better.

You can, with an adaptor, fit the HepVo valve anywhere on a run of pipe.

 

[Richard C]

Strictly speaking a HepVo valve is not an anti-syphon trap, but will do the job of one allowing water or air in one direction only.

Strictly speaking you’re right of course but why split hairs, it does the same job.

As Charnwood’s post you can fit them anywhere in the run but, personally, I would fit as close as possible to the unit. You can get some pretty disgusting crap build up in a horizontal pipe run, fit them too far down the line & you will gets smells.

 

[Charnwood]

why split hairs, it does the same job.

International League Of Pedants. Motto: Accuracy over tact.

you can fit them anywhere in the run

But they must be fitted - if not in a vertical position - with the ripples facing downwards.

 

[Richard C]

you can fit them anywhere in the run

But they must be fitted - if not in a vertical position - with the ripples facing downwards.