Possible AAV problem - morning smell

[Duchy33]

View attachment 164325 We recently moved into a Victorian terraced hose and think there is a problem with the AAV Dirgo valve installation possibly fitted in previous renovation when an outside stack seems to have been removed to accommodate a conservatory style roof installed to replace a slate/tiled lean to roof.
As can be seen from the image the AAV runs off the toilet waste & is positioned close under the conservatory roof.
First thing in the morning there is a foul waste smell in the conservatory which disappears after a short while. There seems no rhyme or reason to it as it's sometimes worse than others & sometimes there isn't a smell (although this is infrequent)
On the half landing up from the toilet is the bathroom & shower, so the AAV is lower than the waste of the hand basin in the bathroom, which seems to be the highest waste point.
We are assuming that the problem is caused by the AAV being fitted lower than the hand basin waste. Do you think this could be the problem?
If so would fitting an anti-vac bottle trap to the hand basin help?
Don't really fancy having a new roof panel made so that we can vent into the outside.
Any advice or recommendation appreciated.

 

[Newboy]

We are assuming that the problem is caused by the AAV being fitted lower than the hand basin waste. Do you think this could be the problem?

Not usually a problem - the reason for fitting the AAV higher than the overspill level is to prevent problems in the event of a blockage.

It's possible that the AAV is not sealing correctly.

If so would fitting an anti-vac bottle trap to the hand basin help?

Unlikely


Where does the white waste pipe discharge?

 

[Duchy33]

Thanks for the reply. The white waste pipe is from the bathroom sink & is joined (not shown in pic) from the hand basin in the toilet & discharges into the soul pipe about a metre below the AAV

 

[Newboy]

Try putting a thin polythene bag (bin liner) over the AAV and sealing it to the stack - see if there is any movement of the bag when the pan is flushed.

 

[Duchy33]

Thanks again. I can't get to it at the moment but will do so over the next day or two & report back.

 

[Hugh Jaleak]

Problems often arise when open vented stacks are cut down and the open end sealed with an AAV. Victorian drainage was usually laid to the letter of the rule book, and doesn't take kindly to sources of ventilation being removed. Try the plastic bag trick, if you see it trying to expand, then the AAV is obviously letting by, but more importantly there is positive pressure trying to escape the drain, cause of which needs investigating.