Poo-maggedon - soil pipes

[MortarThePoint]

We're changing the layout of the bathroom (see images below) to move the toilet. There is a hole in the concrete floor that is poorly placed but needs to work. I originally planned to use a Double Branch (SP230) to route the pipes to the two toilets that need to be served by this stack. That was a bad plan due to the resulting size of the box-in, but we're looking to move one of the toilets now anyway.

 

A Corner Branch (SP232) would work a treat, one socket heading to the wall and one along the wall, but the are fabricated to order. Even with the corner branch, the socket pointing at the wall would be a bit too long so need a large hole in the wall to work.

 

What I have arrived at is in the diagram below. It's a bit weird in that it involves mounting a double branch at 45 degrees. The concern is around cross flow. Is this a crazy idea of something that happens?

 

Room Layout Change:

 

Original Plan:

[ProDave]

I think "swapped contents" is the issue.  Much less likely as the 2 pans are not directly back to back.

 

When I needed a corner branch I gone one off the shelf from someone on ebay.  Looking again there are plenty there but some at silly prices.

[MikeSharp01]

Why would you get cross flow at 45 Degrees it (the fluids / solids) will get broken up by the bends before they get to the drop, start to fall as soon as the bend starts and worst case they hit the bend lower down on the other side and anything that might 'stick' will be washed away by the next flush on the other WC plus you have great rodding access down the top hole of the three way SP230.  

[MortarThePoint]

8 minutes ago, ProDave said:

I think "swapped contents" is the issue.  Much less likely as the 2 pans are not directly back to back.

 

When I needed a corner branch I gone one off the shelf from someone on ebay.  Looking again there are plenty there but some at silly prices.

 

The toilet the other side of the wall would be after a couple of 90 degrees so I think unlikely to receive any gifts from the ne in this room. It's the other way that I'm more concerned about as the pan would be directly connected to the branch. It could have a small vertical offset though to help

 

Edited September 8, 2023 by MortarThePoint

[MortarThePoint]

I guess this is a possible solution to cross flow. Rodents shouldn't be problem as we are having a sewage treatment plant so a closed system as far as a rate is concerned.

 

Anti Back-Flow and Rodent Barrier Valve

https://mcalpineplumbing.com/wc-connectors/wc-connector-accessories/arb-1-anti-back-flow-and-rodent-barrier-valve

[MortarThePoint]

This is where I am ending up I think. Not using the 45 degree double branch but a couple of single branches (SP190) instead. The one facing the floor is to be rotated 90 degrees to face sideways. This does increase the size of the box-in, will need to extend 820mm along the wall behind one of the toilets, 820(l) x 200(w) x 240(h) / 360(h) .

 

If I need to I can attach a smaller AAV to the boss on the horizontal branch.

 

It leaves the socket for the first toilet about 205mm plus the distance between the first branch edge which if I don't use a soil pipe offset or widen the hole is 70mm from the wall. If I then use a compact offset pan connector the toilet's spigot needs to be 205+70+31=306mm from the wall. That won't work with a Close Coupled toilet (unless a box-in behind toilet all the way up) so will have to be a more tradition style like the one below. If I don't use a soil pipe offset, there is possibly room for a 3-way boss to connect the other en-suite's shower/basin (40mm) to. If not it will mean I have to have an ungodly 3no. bend snaking to get it to a boss below the HCF. The side boss (facing the wall) of the first branch could have the macerator connected to it.

 

I wondered about using an access 90 (SP169) but fear it would create turbulence in the flow from the second toilet which wouldn't be good. Hopefully a blockage there is unlikely(?)

Plan View:

 

 

Cove Low Level Toilet incl. Lever Cistern + Seat

 

[MortarThePoint]

An adaptation to move it closer to the wall. 210mm + 36mm for a 20mm or 40mm Offset Rigid WC connector (or MACFIT 20mm / 40mm) and minus ~16mm for plaster and tile give >=230mm  for back of cistern to wc connector distance. That may allow some close coupled, but certainly plenty of traditional style options. (a straight option is unlikely to work but is MAC-1 .

 

About 200mm between the centre line of the loo in this room and the higher part of the box-in. That allows the pan to be up to 400mm wide at that point which is unusual (most narrower than that at their widest).

 

Still another boss to use for a 32mm pipe. Also a second new boss to use below the floor for a 50mm shower waste.

 

 

 

 

[MortarThePoint]

Below is a picture of how all of this as ended up. You can't see that below HCF there is the 50mm shower waste joining, but just above the HCF you can see the two 40mm waste pipes (bath&basin from this room and shower&basin from next room). Also out of view is a 32mm pipe that forms a possible future connection point for a loft toilet (via macerator). The grey and black 90 elbows bring the stack to the wall and an AAV goes into the top. On the right of the image, you can see the 90 bend going into the wall for connection to the toilet in the next room. Around the middle of the photo is the connection point for this room's toilet.

 

Rodding access is perhaps not as good as I could have done (90 bend  through wall could perhaps have been an access bend). Hopefully this can be rodded up to the stack through the toilet pans. Down the stack will hopefully be roddable through the two 90 bends (though the grey one is a tight bend) having removed the AAV and if not the by pulling out both bends as well as the AAV.

 

Edited July 15 by MortarThePoint

[MortarThePoint]

@Nickfromwales Jethro may have made a whoopsie on this one. I'm worrried that the 40mm  pipe entering the stack circled in red is a problem for two reasons:

1. It's 180mm rather than min. 200mm offset from the 110mm branch entry from the WCs. Does the Floplast SP190 Branch count as swept and mean I'm OK?
2. It is directly opposite another 40mm pipe. I think I've seen a fair few other setups like this though or am I imagining it?

Am I right to worry, or do you think it's all within the slack of interpretation?

 

Edited July 24 by MortarThePoint