Hi Hope that someone can advise on this problem. Went to a new build house, 7 months, owners having problem with downstairs toilet and main bathroom toilet which gurgles shower trap when flushed. There are 2 ensuite toilets which go to an external soil pipe open to the air, these are ok. The downstairs toilet and main bathroom are in the middle of the house and have seperate soil pipes going straight down through the building, each has an air admittance valve on top and are boxed in. When flushed the toilet bowls fill right up before draining, I gained access to the valves and removed the top covers opening the soil pipe to the air and both toilets flushed normally, the shower didn't gurgle. I dont know a great deal about these valves anyone have any ideas on how to overcome the problem. Many thanks in anticipation.
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View the thread, titled "Air Admittance Valves" which is posted in Air Sourced Heat Pumps Advice Forum on UK Plumbers Forums.
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Guest123
All AAV's must have a grille or some form of ventilation when boxed in to allow air in for them to work. Not enough free air is circulating to your AAV. Fit a rectangular grille and this will help solve your problem.
I'd also consider removing the two existing ones and fitting A1 rated ones from Floplast which can be reliably fitted anywhere and even below the overflow height of the highest appliance. The push fit version allows easy removal for servicing or replacement.
I'd also consider removing the two existing ones and fitting A1 rated ones from Floplast which can be reliably fitted anywhere and even below the overflow height of the highest appliance. The push fit version allows easy removal for servicing or replacement.
Thanks for replies, stegas, I don't think that the valve is opening to allow air in, as by removing the cover I am allowing air in, and the toilets flush as they should. system3 as you say there doesn't appear to be any ventilation in the box work, but until a couple of weeks ago the customer says that all was well with the flushing.
G
Guest123
Just to add, any AAV needs to draw air into it in order for it to work. In a pipe chase or boxed in area, the amount of air is limited. They will work for a while, but eventually they will fail. I'm not going to describe or draw diagrams here about negative or positive pressure and how the technical details of how these valves work!
I was at one last year with this problem and a complete office block of toilets were out of commission because of this and the smell of raw sewage hit you when you walked in the front door. I removed the cover of the pipe chase, replaced the AAV, fitted a couple of decent chrome grills and the problem was solved.
I was at one last year with this problem and a complete office block of toilets were out of commission because of this and the smell of raw sewage hit you when you walked in the front door. I removed the cover of the pipe chase, replaced the AAV, fitted a couple of decent chrome grills and the problem was solved.
with air testing on new builds rooms and boxings are even more air tight than ever meaning vents are more important. It always best to try and get the AAV's into to loft space for air and easy of access. Trouble is most chippys box them in to tightly making to hard to change a AAV valve.
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Plum Bob 66
Surely if the soil pipe was blocked the toilet would eventually back up after repeated flushes?. Think systems right on the money here, i had same issue a year back and fixed it with new durgo valve.
G
Guest123
The OP stated that the rise in water level in the toilets returned to normal once the AAV covers were removed. When replaced the water level rose again. This is a problem with the AAV's and not a blockage. A blockage or even a partial blockage would have a constant effect on the water level which is not happening. The diaphragms in the AAV's are sticking most likely due to wear and having to operate with very little air in the sealed box to make them function properly. I've seen this many times. All AAV's require a free flow of air for correct operation and in situations where they are boxed in, a decent sized quality air vent/grille should be fitted to the boxing in section.
G
Guest123
I know, dem kidz seem to know better and would argue that black is white and their young pals jump into agree with them.
I have returned to house and taken photos of valve in downstairs toilet. Photo 1 shows boxing in, photo 2 shows valve with lid removed, doing this allows toilet to flush. Photo 3 shows the diaphragm removed, no mechanics or springs involved. Photo 4 is from above with lid and diaphragm removed and 5 a side view of valve, solvent weld on pipe. When I put it all together again and leave the top off box allowing air to enter it still does not work. system3 does this set up agree with what you stated in your earlier response. The valve in the main bathroom is boxed in with a tall bathroom cabinet surrounding it. As mentioned by stegas the diaphragm doesn't raise when toilet is flushed
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Plum Bob 66
Not surprised it didn't work there needs to be some ventilation to let the science take effect.Like system advised fit a pretty grill to allow descent airflow,test, get paid and adios,job done.:clap:
The clue is in the name: Air Admittance Valve.
Impossible to admit air when it is fitted in a sealed box.
Photo 2 shows there is some space which allow some air to be available but not enough for the valve to work properly.
If the diaphragm does not raise then it appears it is not working anymore probably because it could not work as designed for seven months.
G
Guest123
I suggest that you buy ONE of the push fit (easily removed) A1 valves I suggested earlier and fit it in the box. Seal it up and fit a grille. If it doesn't work, then as the valve is pushfit, it can be removed and returned for a refund.
To properly commission the valve after fitting it and before boxing it in, flush the toilet several times to get the valve going.
To properly commission the valve after fitting it and before boxing it in, flush the toilet several times to get the valve going.
K
Koogatubac
System, i thought the same problem was the AAV's, took them off and the toilets worked normal, slowly screwed them back on and the water level rised.
This was on the 2nd house from 4 houses.
Setup was full stacks in bathroom and stub stacks with AAV however 1 in every 4 houses had to have 1 natural ventilation (head of the drain)
I originally thought the AAV's were faulty
What happened was at the head of the drain (where the blockage was) brought all human waste up in their 1st level toilet. Drainage guys came out, half a day unblocking in a road, ended up being in the drains, they put a equal tee piece.
It was wrong and needed to be a swept tee. Thats where it was blocking up.
After that the toilets worked normal. So the AAV's werent faulty
This was on the 2nd house from 4 houses.
Setup was full stacks in bathroom and stub stacks with AAV however 1 in every 4 houses had to have 1 natural ventilation (head of the drain)
I originally thought the AAV's were faulty
What happened was at the head of the drain (where the blockage was) brought all human waste up in their 1st level toilet. Drainage guys came out, half a day unblocking in a road, ended up being in the drains, they put a equal tee piece.
It was wrong and needed to be a swept tee. Thats where it was blocking up.
After that the toilets worked normal. So the AAV's werent faulty
G
Guest123
Koogatubac, OP's description and experience of this was similar to a problem I had last year in a office block. It was the AAV's and lack of air that was causing it. The OP has also taken onboard your concerns about a blockage and therefore is going to replace a AAV AND rod the drain, so either way, the problem will be solved.
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