removing an AAV on inspection chamber

[rebuilder]

This is a a 1960 house bought a year ago with a squarish brick sewer inspection chamber at the rear of the house. Two 4" waste pipes empty into this chamber that run under the house with one from the bathroom and the other a small toilet.

Off this chamber a 4" earthenware pipe runs to the side of the garden wall and an old fashioned AAV valve is on this. The sort that were common on side of houses a long time ago which are no longer seen in new buildings.

The two 4" sewer pipes from the house are vented. I cannot see the needed for this AAV valve.

The workmanship on the inspection chamber was poor and the main split half round pipe that runs to the main sewer is too level. This causes solids to back up the pipe that serves the AAV which is opposite to the pipe that runs to the main sewer.

Thames Water came and looked with the guy saying off-hand that the AAV could be removed and portland cement used to block up the pipe in the inspection chamber and shaped so as not cause solids to linger. He was not emphatic, just mumbling.

Is he right? I cannot see the need for this ugly AAV in the garden. The two house 4" pipes are vented. One with an AAV and vented. I notice these AAVs are not seen any longer in new houses and assume that this was was overkill when fitted.

Comments appreciated.

 

[Nige F]

Thames Water came and looked with the guy saying off-hand that the AAV could be removed and portland cement used to block up the pipe in the inspection chamber and shaped so as not cause solids to linger.

Is he right? .

Yes.

 

[rebuilder]

Many thanks. Is Jetcem cement equivalent to Portland cement? It claims to to be useful for where water is present.

 

[rebuilder]

Any views on Jetcem?

 

[Hugh Jaleak]

Unusual for a property of that vintage to have an AAV as you describe, the Victorians often fitted them but they soon went out of vogue as unnecessary and problematic. Idea was the house drains were sealed from the main sewer by the interceptor and the AAV allowed air in to the system to be vented via the stack and thus provide a flow of air through the house drainage system.

No harm in doing away with it, use a strong sand/cement mix (or granolithic mortar even better) to seal it off in the chamber, (shape to suit benching), never used Jetcem but a rapid setting product may be beneficial so to allow prompt reinstatement of the drains.