Gurgling shower drain

[Tomfromsurrey]

Hi, I have a new build property with 2 en-suites with showers. After running the shower for a short or long time and turning off, the shower drain starts to gurgle for around 20 to 30 seconds. Both shower drains go to a soil stack with an AAV in the loft. Removing the AAV does not change the problem, neither does opening the outside rodding point cover. Water flow is good. WC flush is OK. Same problem on both showers. Shower drain pipes are probably accessible under the shower trays.
Drain flow wis good
Any ideas would be welcome.

 

[SimonG]

Waste pipe too long for size.
Waste pipe doesn't have correct fall.

 

[Deleted member 120897]

Too close to a tee branch on waste?

 

[Tomfromsurrey]

Hi, I have a new build property with 2 en-suites with showers. After running the shower for a short or long time and turning off, the shower drain starts to gurgle for around 20 to 30 seconds. Both shower drains go to a soil stack with an AAV in the loft. Removing the AAV does not change the problem, neither does opening the outside rodding point cover. Water flow is good. WC flush is OK. Same problem on both showers. Shower drain pipes are probably accessible under the shower trays.
Drain flow wis good
Any ideas would be welcome.

Also see my other topic, Basins with push button wastes not emptying - https://www.plumbersforums.net/threads/basins-with-push-button-wastes-not-emptying.122893/
Same en- suites

 

[hometech]

introduce some AAV at point of drain. I had the exact same issue.

 

[Tomfromsurrey]

Thanks so far. All the pipe work bar the run from the waste to the floor, is under the floor. I am going to try and get an endoscope under the floor to have a look

 

[Julie Street]

Basin waste pipe is probably teed into shower waste pipe under floor.
There may be a backfall to the shower trap from the basin, creating a siphon effect between basin and shower. Pushing the click clak plug adds a bit of suction and gets the siphon to empty the pipe.
Unless you want to access the pipes under the floor to rectify the fall, your only hope is to replace the basin traps with air admittance traps and hope for the best!

 

[Tomfromsurrey]

Thanks Julie. I think you are right. I don’t particularly want the floor up or the ceiling down underneath.
Are there air admittance valves that ca be fitted inline in the horizontal drain pipe under the shower tray?

 

[Julie Street]

You could have a look at these but Im honestly not sure whether they can be installed below the flood level, you would have to confirm with McAlpine.

Ventapipe 25 with integral 1½" Multifit Tee | McAlpine Plumbing

Optimize air ventilation with the Ventapipe 25, featuring an Integral 1½ Multifit Tee for efficient connections.

mcalpineplumbing.com

Personally I would try the basin traps first its easier!

https://www.NoLinkingToThis/p/mcalpine-anti-syphon-bottle-trap-white-32mm/37314?_requestid=241384

 

[Julie Street]

Ive sometimes managed to eliminate gurgling from 1 sink by installing anti siphon trap in another sink connected to the same drain. Ahh the mysteries of fluid dynamics..

 

[EvilDrPorkChop]

Bet there's a waterless trap after the shower trap. It's not a Redrow house by any chance?

 

[Tomfromsurrey]

Bet there's a waterless trap after the shower trap. It's not a Redrow house by any chance?

No not a Redrow house but the plumber that installed the plumbing was not good. after thhe shower trap there is a length of drain pipe that disappears under the floor. As far I can ascertain there are 2 basins and 2 showers all teed together before going to the soil stack. That has an AAV on it in the loft. I have an endoscope but it’s difficult to find anywhere to get it under the floor.

 

[Tomfromsurrey]

I managed to get an endoscope down one of the 32mm basin drains by removing the basin trap. First the drain pipe is pretty disgusting with black sludge from, I assume, soap etc. I live in a hard water area so I don’t know if that makes it worse. So, going down the drain it’s difficult to see which way the pipe goes as I can’t tell what the orientation of the camera is. The endoscope is not an expensive one and has a short focal length so not a lot in focus at the same time. Anyway, going down below the floor in hits pooled water, which I assume is caused by a sag in the pipe work, or possibly a partial blockage further on. What can be used down the vertical basin drain pipe to rod the pipe work to the stack? A snake?

There are no rodding points on the 2 en-suite drainage pipes. The only entry points are the basin drains after removing the traps. The only way I can see to fix this pipe sag (or belly), if that is the problem, without lifting the tiled floor or removing a section of ceiling below is to install new surface drain pipes in the en-suites and drop the pipe into the 110 mm pipe through the floor at one point. Maybe a 50mm pipe with the 2 showers and 2 basins teed into it.?

Any other ideas would be welcome

 

[Julie Street]

I managed to get an endoscope down one of the 32mm basin drains by removing the basin trap. First the drain pipe is pretty disgusting with black sludge from, I assume, soap etc. I live in a hard water area so I don’t know if that makes it worse. So, going down the drain it’s difficult to see which way the pipe goes as I can’t tell what the orientation of the camera is. The endoscope is not an expensive one and has a short focal length so not a lot in focus at the same time. Anyway, going down below the floor in hits pooled water, which I assume is caused by a sag in the pipe work, or possibly a partial blockage further on. What can be used down the vertical basin drain pipe to rod the pipe work to the stack? A snake?

There are no rodding points on the 2 en-suite drainage pipes. The only entry points are the basin drains after removing the traps. The only way I can see to fix this pipe sag (or belly), if that is the problem, without lifting the tiled floor or removing a section of ceiling below is to install new surface drain pipes in the en-suites and drop the pipe into the 110 mm pipe through the floor at one point. Maybe a 50mm pipe with the 2 showers and 2 basins teed into it.?

Any other ideas would be welcome

But then you would still have to get enough fall on that new pipe, then box it all in. Then cap off the old pipes somewhere.

Are there any external walls that you could just send a new pipe out of?

The black stuff is general gunge not helped by it being constantly wet due to pooled water. You could try a flexible snake but in the long run you need to fix the basic problem.

If it was my house I would be taking the floor up, if only to see what other delights await.......

 

[exedon2]

You said in your first post your property is a new build?
If so why are you even thinking about this problem? Surely the solution lays with the builder/developer/Plumbing contractor?

 

[Tomfromsurrey]

The builders plumbers are being awkward as they probably know they need to take the floor up, so I am trying to gather as much information as possible to have a discussion with them.
Question, is there an air admittance valve that can be installed in the horizontal pipe from the shower trap under the tray to where it goes down under the floor. The pipe is about 1400mm long.
Thanks

 

[Tomfromsurrey]

The builders plumbers are being awkward as they probably know they need to take the floor up, so I am trying to gather as much information as possible to have a discussion with them.
Question, is there an air admittance valve that can be installed in the horizontal pipe from the shower trap under the tray to where it goes down under the floor. The pipe is about 1400mm long.
Thanks

It’s a tiled floor by the way so a big job to take up.

 

[exedon2]

Assuming floor has been fixed correctly tiles will be least of there problems!
I would think you have N H B C guarantee or similar? Get them on board as well.

 

[Tomfromsurrey]

Mcalpine have an A1 rated AAV, VPSF-40/50
As A1 rated it can be installed above or below the flood plane so I guess It could be instaled in the 1.4m of 40mm drain under the shower tray.