Soil venting issue

[plumber89]

Hi ,
having an issue with a bathroom I installed 5-6 month ago , it's seems as though the toilet is struggling for air and not venting properly.

originaly the soil stack was external and vented to the atmosphere , the customer has had a conservatory installed so the soil stack has been cut lower and a Durgo has been put in , this Durgo is a lot lower than the basin overflow ,( although i have heard a lot of durgos can be installed lower than this now )

as as the toilet is flushed the water rises and takes a while to go away and sometimes splutters through the shower waste as if ts trying to grab air as this is the nearest trap .

i have taken the Durgo off and replaced it with a new one and the same thing happens , the only way I can solve this is to take the Durgo off completely and then the problem goes away , but obviously the customer would be left with a smell in the conservatory

the Durgo is about half a foot above the tee that goes to the wc , the wc is 1.4 meters before vertical drop ,

What is regs on durgos regarding length of run for one to work, or how high they need to be situated , as it is as though when the toilet is being flushed the vacume in the soil pipe is to high to allow the Durgo to open and allow air into the system ,

I have small access to the soil pipe and could put a strap boss into soil with 50mm pipe and a small air admittance valve closer to toilet to see if this AIDS the toilet in getting air ,

if if not I can cut into soil and put another Durgo in but this would involve a lot of removing of boxing etc
i would leave old Durgo in , can two durgos be installed in same soil stack ? Or will they counteract each other ?

do durgos have a working temperature ? As his is in a conservatory and has only started happening as we have had this extremely hot weather ? Just a thought as the problem goes away when Durgo is removed from system

many thanks

 

[JCplumb]

AAV's can fail, doesn't happen often in my experience but does happen, as the installation worked fine at first then that would be my first guess.
Do sinks/baths drain as fast as they should? Could be a blockage somewhere, anyone been putting wet-wipes or anything down the loo?
Don't think you will have a problem installing another AAV they won't cancel each other out.
Is the toilet a vanity type? If so maybe think about using a pan connector with 40mm boss and pipe a new AAV on there, it should be above flood level. i.e. above the overflow of the cistern.

 

[oz-plumber]

It's probably the wrong vent for the system.
All drains need an open vent to atmosphere to allow for a positive pressure release.
AAV's only allow air into the drain in a vacuum situation, they do not release air when a positive pressure is encumbered.

All stacks should be vented to atmosphere.

AAV's were really only designed for a single fixture, such as a sink or basin, which could not be vented from the appliance.

I would never use an AAV on a pan, even in the most dire of circumstances.

 

[Howsie]

All stacks do not have to be vented to atmosphere, have a read of Approved Document F for info and regs.

 

[snowhead]

It's a blockage.
It's nothing to do with the AAV.

It's either coincidence it started when the conservatory was added or it was caused by that work.

Has the conservatory got a nice tiled and GROUTED floor.

Where did the tiler wash his bucket out?

 

[Spanish]

I agree, timing may have thrown you but sounds like a blockage

 

[rpm]

Where did the tiler wash his bucket out?

OR Any sign of a pack of wet wipes in the room by any chance?

 

[plumber89]

Hi there ,
Basically there is a Durgo venting the system , which does not seem to open when the toilet is flushed , as removing the Durgo solves this

Fitted a 50mm AAv via a strap boss behind the toilet , and without the AAv attached the problem goes away but as soon as I put the AAv on the problem starts again

So it is as though the Durgo/ AAv are not opening when toilet is being flushed ,

Can a blockage in the system cause this ? Thought a AAv / Durgo would open no matter what when a toilet is flushed etc ,

Have tried a brand new Durgo and same thing happens ,

The conservatory was fitted before bathroom was fitted , and bathroom has been fine for 4-5 months

 

[JCSPLUMBING]

Have you opened the drain cover and had a look yet?

 

[tamz]

It has a partial blockage. When you flush the toilet it creates back pressure and holds the durgo shut.
Get yer rods out

 

[Staffy85]

"Can a blockage in the system cause this ? Thought a AAv / Durgo would open no matter what when a toilet is flushed etc , "

I would say blockage too, Air admittance valves let air in when its under vacuum , i.e if your sucking on the waste pipe it would open and draw air in from it instead of pulling the water out of the trap , in your case when the water is entering the system the air has to go some where because its blocked and that cant go out the AAV as it doesn't flow that way {otherwise smells would be entering the room} , removing the AAV allows the air to escape which is normal in this scenario , if the waste pipe was clear the air would escape naturally further along to the nearest vent..

 

[oz-plumber]

Has the system got a vent to atmosphere anywhere, or are you now just relying on the AAV?

 

[Howsie]

All an AAV does is let air in not out, so what you're experiencing is the symptoms of a partial blockage. Removing the AAV lets air out and so you don't experience the problem. As Tamz has said, its rodding time.