Will my bath or shower waste layout cause trap siphoning?

[Antonio King]

Just wondering if this pipe layout might cause any trap syphoning from the shower or bath traps.

Bath waste run is 2m x 40mm pipe from trap to tee, which connects directly to the soil pipe. The shower waste run is 1.5m x 40mm pipe and connects to a tee which is joined to the bath waste run and the soil pipe.
The soil stack is 110mm and is vented.

I've attached a pic of the layout, birds eye view.

Thanks in advance!

 

[Sharp Point]

Yes, there’s a strong possibility that the bath emptying could pull the shower seal out. Each appliance should have its own run to the stack.

 

[Millsy 82]

Is the tee literally right next to the soil as pictured?

It's not best practice but it seems to be common practice now but if its right next to the stack I doubt it will siphon out the shower trap.

 

[SimonG]

I always have ran individual lines.

 

[Antonio King]

Yes, there’s a strong possibility that the bath emptying could pull the shower seal out. Each appliance should have its own run to the stack.

Thanks for the response. So best option is seperate runs. Are there any alternatives? Anti-vac/syphon trap on bath and shower?

Is the tee literally right next to the soil as pictured?

It's not best practice but it seems to be common practice now but if its right next to the stack I doubt it will siphon out the shower trap.

Yep, literally 1 end of the tee is connected to a short boss pipe. What about the shower waste syphoning the bath trap? I guess this is less likely as the shower will be free flowing rather than a large body of water like emptying a bathtub?

Thanks

 

[townfanjon]

Separate pipes as is reasonably practical, personally I think that would work . ( crossing fingers )

 

[Millsy 82]

Thanks for the response. So best option is seperate runs. Are there any alternatives? Anti-vac/syphon trap on bath and shower?

Yep, literally 1 end of the tee is connected to a short boss pipe. What about the shower waste syphoning the bath trap? I guess this is less likely as the shower will be free flowing rather than a large body of water like emptying a bathtub?

Thanks

If practically possible then run separate to the stack. Sometimes within this job things are not always possible so you have to adapt.

The way you have drawn it personally I wouldnt be too worried about. If you had say a 1mtr long run then I would be more concerned as then that probably would suck your trap out.

Not sure if you can get antisyphon bath/ shower traps. Could fit a hepvo or what ever they are called. Or you could run a 1.5 pipe to say the corner of the bath and fit a small surge underneath problem with that is you would somehow have to vent underneath the bath.

 

[Burger]

Yes, you could try some of these:

Bath Traps, Fillers and Wasteflow

Multifit In-Line Non-Return Valve

 

[Antonio King]

Thanks everyone. I think I'll just test this setup and then correct it after. I'm fortunate to have all the pipework exposed in the room below the bathroom so fixing any siphoning issue will be easy to do. Just picking your brains!

 

[Sharp Point]

Thanks everyone. I think I'll just test this setup and then correct it after. I'm fortunate to have all the pipework exposed in the room below the bathroom so fixing any siphoning issue will be easy to do. Just picking your brains!

If you have all the pipework exposed, pipe each appliance separately.....job done and you keep us all happy

 

[Antonio King]

If you have all the pipework exposed, pipe each appliance separately...job done and you keep us all happy

Good point!

 

[Steve weightman]

Maybe drop an hepv0 on the shower pipe to avoid siphoning