Drainage Alterations

[shaky1105]

Hi peeps. I wonder if some of you guys could have a quick look over the ideas I have for altering the drainage due to my bathroom refurb I'm starting on please and see if there are any glaring errors to my plans ?

We haven't got our own soil stack at the moment (it's a late 1970's/80's bungalow) and we did used to occasionally get bubbling in the toilet pan and sewer smells in the bathroom (even though the neighbours have a soil stack terminating in their m/h) hence why I would like to add one to my property.

Hopefully, I have drawn it well enough to explain what I want to do but I'm sure I'll get a few comments on what's wrong/right

TIA.
Oops, forgot to add that the Shower, Bath & Basin wastes will all be above ground.

 

[Hugh Jaleak]

Looks ok provisionally, although if drain isn't too deep I'd look at putting a small inspection chamber where the new WC run joins the existing run. (Could theoretically unblock from an access bend where it comes through the wall, but working upstream with a pipe full is never the best idea....) Keep bath waste as short as possible, I'd connect that into the 110mm from the WC above ground if you can.

 

[shaky1105]

Looks ok provisionally, although if drain isn't too deep I'd look at putting a small inspection chamber where the new WC run joins the existing run.

I did wonder if a small inspection chamber in the connection might be an option - thanks. Seeing as the drain in the neighbours M/H is only about 600mm deep it shouldn't take too much finding I reckon.

Keep bath waste as short as possible, I'd connect that into the 110mm from the WC above ground if you can.

The idea for letting the bath waste into the soil stack instead of the WC pipe was to try to avoid any possibility of a large sudden flush (you know what I mean ) causing a vacuum and sucking the water out of the bath trap. This used to happen regularly in a friends house and he had no way of fitting an aav on the bath waste to try to get around the problem. Just about everytime someone went forra dump, they had to wait until the flush was finished and then pour a couple of cupfuls of water into the bath to stop the bathroom stinking

The bath waste run will be less than 3M with two 90° bends where it exits the wall on my plan, although I could fit an aav on the bit of pipe that comes through the bathroom wall into the garage and then strap-boss that onto the WC outlet if you reckon that's a better idea ? I was trying to get any pipe out of the garage if possible but it's no problem to leave a bit in.

This is only the second bit of soil drainage I've ever done so I want to get it right first time if I can.

 

[Hugh Jaleak]

At that depth a shallow inspection chamber will be fine, if need be fit it on a slight angle so the WC connects to the through channel, this avoids the incoming flow overshooting and fouling the benching/sitting in unused channel entries opposite.

It's the 2 90° bends on the bath waste that worry me, if you want to go with that option, 2 45° bends would be a better option, although I think it would be unlikely you'd have issues, the WC would have to fill the 110mm pipe and put a vacuum behind it to pull the bath trap, given the setup planned here, that's unlikely in my view. Alternatively, fit the chamber at the top end of the run, where the WC comes though the wall, and couple in the bath onto one of the unused inlets.

 

[shaky1105]

At that depth a shallow inspection chamber will be fine, if need be fit it on a slight angle so the WC connects to the through channel, this avoids the incoming flow overshooting and fouling the benching/sitting in unused channel entries opposite.

That sounds like a plan to me Hugh Thanks. Should be straight-forward enough to expose the joint and replace it with a chamber.

It's the 2 90° bends on the bath waste that worry me, if you want to go with that option, 2 45° bends would be a better option, although I think it would be unlikely you'd have issues, the WC would have to fill the 110mm pipe and put a vacuum behind it to pull the bath trap, given the setup planned here, that's unlikely in my view. Alternatively, fit the chamber at the top end of the run, where the WC comes though the wall, and couple in the bath onto one of the unused inlets.

I bow to your superior knowledge here obviously Hugh and wouldn't attempt to question you know what you're talking about.......BUT just as a "belt and braces approach" (I'm paranoid about stink in the bathroom - lol) if I leave in the short section of bath waste (about 400mm) that exits into the garage before strap-boss'ing to the new WC soil pipe outside, could I fit an AAV on that bit to help against the possibility of the trap being pulled ?

Thanks again for your help.

 

[Hugh Jaleak]

if I leave in the short section of bath waste (about 400mm) that exits into the garage before strap-boss'ing to the new WC soil pipe outside, could I fit an AAV on that bit to help against the possibility of the trap being pulled ?

If you are that worried, fit a junction on the 110mm soil pipe from the WC where is comes through the wall, and put an AAV on the top of that. Pan connectors are made with a boss connection for a waste pipe, if there was any major issue with WC's pulling traps, these Pan connectors wouldn't be used.

My concern with your proposal to use 2x 90° bends was, it makes that section of pipe an absolute pig to get a snake or similar apparatus along it should the pipe ever need cleaning out. 45's are somewhat easier to get around.

 

[shaky1105]

If you are that worried, fit a junction on the 110mm soil pipe from the WC where is comes through the wall, and put an AAV on the top of that. Pan connectors are made with a boss connection for a waste pipe, if there was any major issue with WC's pulling traps, these Pan connectors wouldn't be used.

My concern with your proposal to use 2x 90° bends was, it makes that section of pipe an absolute pig to get a snake or similar apparatus along it should the pipe ever need cleaning out. 45's are somewhat easier to get around.

Sorry for the late reply (family issues) and thanks Hugh. I see your point now re: the bends on the bath waste. I'm quite happy to go along with your original suggestion of running the bath waste into the soil outside. Sorry for being so paranoid and not listening to an expert .

I'll start collecting all the gear I need once I've got the wall cored. at least I've received my geberit toilet frame now so I can start getting some stuff done.

Thanks again Hugh.

 

[shaky1105]

Can I trouble you with another question please Hugh ? I'm going to be fitting a Wall-Hung Vitra toilet onto a Geberit frame. The frame comes with a 90° 90mm bend piece that firmly attaches to the frame but I wanted to take the pipe straight out of the back of the toilet, through the wall outside as I've seen a few threads that say to keep 90° bends to a minimum. Seeing as if I used the 90° piece supplied, there would be three 90° bends before the pipe disappeared under ground level, I also bought one of the Geberit straight 90mm/110mm connection pieces.

The question is:- There is a reasonable amount of "give" in the frame clip so I could angle this down easily to match the 92.5° (and more if required) bend that I will be fitting outside the wall to give a 2.5° slope but I've also seen reports that this will not be enough of an angle so close to the toilet to give a good clearance rate, especially when using a low-flush volume cistern which the Geberit is, or a 90mm outlet toilet pan which the Vitra is. Admittedly, the cistern can be adjusted for a 7.5L flush which may help but I just wanted to make sure I get this all correct in my mind before I start in earnest.

Cheers.

 

[Hugh Jaleak]

Sorry, only just seen this. Yes, 2.5° should be ample, as long as it's got a slight fall on it through the wall, it should be fine. The weight/velocity of the flush should be sufficient to clear the pan, once it's through the outlet, gravity will take over.

You are right to keep bends to a minimum.

 

[shaky1105]

Sorry, only just seen this. Yes, 2.5° should be ample, as long as it's got a slight fall on it through the wall, it should be fine. The weight/velocity of the flush should be sufficient to clear the pan, once it's through the outlet, gravity will take over.

You are right to keep bends to a minimum.

No worries Hugh. I decided to start a new thread seeing as it was basically a different question so I did that but then realised I couldn't delete this post - d'oh . I got a similar reply to this on that thread as well so at least I know I'm on the right track which is good .

The waste will come out of the wall about 14" above ground level as well which will give me plenty of room to attach a strap boss or even a boss piece.

Thanks again for all your help, at least now I can be certain in what I'm doing will be correct.