Bad Smell

I have a problem with occasionally getting a sewerage whiff in our conservatory. I'll try my best to describe the set-up without resorting to ascii art.

The conservatory is adjacent to a single story kitchen extension. The kitchen has an inaccessible roof space, which probably permits air to flow from it into the conservatory. Through the kitchen roof space runs an off-horizontal soil pipe from the upstairs bathroom. The soil pipe then runs about 40ft to a vented cesspit.

If I remove one of the kitchen ceiling light fittings I catch a strong smell of sewage coming from the roof space.

There used to be a soil stack vent, which was replaced (not by me) with an air admittance valve inside the kitchen roof void. That air admittance valve is a couple of feet lower than the WC and sink.

There is no other vent, other than on the cesspit.

Could an air admittance valve sited below the WC, a long way from the cesspit and effectively inside the building be a problem?

There are other possibilities, involving rats, but I'd like to understand how likely it is that this set-up is a problem before causing excessive work, expense, mess and tears.

Thanks in advance to anyone patient enough to read through this.

Reply to
tonkski
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AAVs generally have to be sited above the waterline (usually a foot above the bog top or so, depending on various factors).

But a Floplast AAV may be sited below the waterline but still needs its top roughly level with the top of the bog - check their website for full specifications.

Your cesspit will probably still need an open air vent somewhere to relieve positive pressure.

Reply to
Tim Watts

Thanks Tim. I'll have to see if I can get a look at the valve. If it's not a Floplast then it needs replacing?

Reply to
tonkski

It might have just got stuck open. Could try a gentle tap, but you probably won't know if that was the cause, or if that fixed it, for some time.

Reply to
Andrew Gabriel

Oh yes. They can stick open and vent the pongs outwards.

Reply to
grimly4

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