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