What trap for basin?

[midsman]

So my bathroom is coming along. Quick question about trap for basin in my situation

So main soil pipe in building (flats) is a soil and vent pipe. My toilet connects into this and is on an approx 2m horizontal run from this main stack. Sink in next to toilet and toilet soil runs behind this. My plan is to boss strap into my toilet run and connect the basin waste to this toilet run. What trap should I use. Is there a risk of Basin trap being pulled when toilet is flushed.

The order of appliance is from right to left. Toilet. Basin. Then main building soil and vent pipe.

Any advice greatly appreciated

 

[Aire]

You should be fine with a standard p or bottle trap but if you are concerned with siphoning then you can get anti siphon versions of both traps.

 

[townfanjon]

As per Craig above , go for an adjustable Macalpine p trap .

 

[chris watkins]

Standard 1.1/4" Mc Alpine bottel trap with 40mm boss & waste pipe right up to the 90 deg bend before the trap, then the 40x32mm reducer & a short of 32mm to the trap. No need for anti-siphon traps just more to go wrong & leak.

No risk of siphoning with a waste connection into WC float serving a single toilet.

 

[midsman]

Many thanks for your replies. Are you saying to use 40mm pipe rather than the standard 32mm?

 

[chris watkins]

Yes, I would always step it up even if it within the maximum 1.7M limit in Part H of Building Reg's.
It is the vertical pipe section that causes the danger of self-siphonal so if you go up a size this will be less likely to run full bore.

 

[midsman]

The soil pipe / boss is directly below the basin and so the run will be approx 70cm vertically. I will do what you suggest though. Nice idea. Is this something that is done in the trade?

 

[chris watkins]

Yes, at least in London by people you have been taught correctly.

 

[Stigster]

The soil pipe / boss is directly below the basin and so the run will be approx 70cm vertically. I will do what you suggest though. Nice idea. Is this something that is done in the trade?

Yes, it's just one of the many things people learn through experience (or informative places like this). It's not required by regulation but there's nothing wrong with doing more (better) than the regulations require, especially where it causes negligible extra expense or hassle as with plumbing a basin waste.

 

[midsman]

Would you therefore use 50mm on a bath. Shower. Kitchen sink. Instead of 40mm

If I need to extend the wc soil float is it acceptable to use a double female end coupler to join the extra piece of pipe. Are soil pipe joints designed to flow in either direction ? With a double female coupler in the middle of a run would mean that the flow would be through joint then into pipe as opposed to pipe then into joint.

 

[ShaunCorbs]

Depends on run but I would always up size

I guess you mean push fit? I’ve never had a problem aslong as you pre the pipe correct eg bevelled both ends etc

 

[Stigster]

In my experience pushfit is a reliable waste system. I apologise for another of my "In the workshop" anecdotes but just like the JG Speedfit I buy because they are so easily re-useable, the same goes for Poly Pipe pushfit waste. I would say our multiple re-use of these fittings is a worst case scenario verging on torture test and if they are reliable then, which they are, one time installation with proper care taken in a person's home would be even more robust. Once again, we reuse them many times to save on my training budget and I cannot remember the last time a properly prepared waste joint failed us.

When correctly supported and installed properly as ShaunCorbs mentions, they are very reliable.

In live jobs in people's houses I would always (and do always) use solvent weld fittings but for those that do use pushfit, I wouldn't worry as I have seen them used and tested many times without failure.

 

[midsman]

Depends on run but I would always up size

I guess you mean push fit? I’ve never had a problem aslong as you pre the pipe correct eg bevelled both ends etc

Many thanks. Yes I mean 110 push fit. I have a bevel making bit for my drill to make the bevel so it fits comfortably into the rubber in the socket. I have spray lube too. Does this mean that it doesn’t matter which way fittings go. For example 110mm joints with a male and female end. They don’t have to be fitted in a certain way depending on direction of flow?

 

[ShaunCorbs]

Normally the fittings I think your on about have one push fit one solvent weld / glued ?

 

[midsman]

I mean these fittings in particular the pipe coupler

 

[ShaunCorbs]

There both female fittings including the elbow

 

[midsman]

There both female fittings including the elbow

Yes. And is that both end being female suitable to join two pipes together on a run or is not good practice as the flow of waste will be going from female to male and not male to female.

 

[ShaunCorbs]

Yes. And is that both end being female suitable to join two pipes together on a run or is not good practice as the flow of waste will be going from female to male and not male to female.

If you cut it cleanly and square you won’t be able to see where the join is / it’s fine

 

[midsman]

Thank you very much. I will bevel both male ends and use lube. So in effect all 110mm push fit fittings are bi directional? The direction of flow doesn’t determine which way the female part on the fitting should be orientated? With a double female end I guess you have no choice especially when going two male ends. But what about on a longer run with bends and t’s. Is it then better to run male to female with the waste flow.

Or as another option would you normally use solvent weld 110mm therefore no leaks as no seal? Or would this be a disadvantage as there is no room for expansion- if for example fitted outside

 

[ShaunCorbs]

Over a long run yes your going to need expansion joints when using solvent weld also loose clips

As for solvent vs push fit tbh these days it doesn’t really matter aslong as you use decent gear

Have you ever tried to turn a fitting a month later with push fit goes to show how good the seal is

And when your 3 stories up working off a ladder you want the simplest

 

[midsman]

Brilliant. Thank you so much for your help. So using a push fit against the flow is okay no matter which way the flow is. They are bi directional? Female to male with flow going through female then male is sound?

 

[ShaunCorbs]

. correct doesnt matter .

 

[midsman]

. correct doesnt matter .

Thank you very much for taking the time to reply and clarify that.