Unique plumbing issue in a 300-400 year old house

[cloudsix]

Hey all,

I'm hoping someone might have some unique ideas for me.

The Issue

We live in a house built in the 1600s. The plumbing has obviously been added to over time.

Occasionally, we get a sewage smell from our kitchen sink (when the dishwasher first runs), our upstairs ensuite sink/show, and our upstairs main bedroom sink and/or bath.

The kitchen issue I can replicate, but the upstairs issue happens at random times and it sure is a strong smell.

The Setup

The house has no outside vent, and instead uses an AAV downstairs, slightly higher than the sink. It uses one AAV for all waste/pipes.

Solutions I've Tried

I've changed the AAV to a new one.

I've had a plumber round who has fitted inline 1-way valves to the pipe from the kitchen sink, and the pipe to the ensuite sink. We did have it on the pipe from the ensuite shower, but the water drained too slowly with the trapped air. The shower now has a mini AAV, but no 1-way trap.

It feels like the smell comes from the sink more than the shower.

The 1-way valves don't appear to have fixed the issue.

Because of the position of the plumbing, there's no clear route to get a vent fitted outside.

Appreciate any help, ideas, or advice you all may have.

 

[cloudsix]

Good observation. And no, indeed unlikely. But it will stop you being able to carry out an air tightness test on the remainder of the system which would seem to have been what your plumbers should have done initially instead of changing traps and fitting valves at random.

If it passes a tightness test, then we can assume a trap. If it fails, you may just be able to find the leak with gas leak spray or similar. If it won't take a pressure at all, then there may be a 20mm hole drilled into the pipework - and yes, I've come across one!

I agree it's definitely worth sealing, either way.

Tightness test sounds like a good starting point once I'm sure this shower trap is fitted properly. Just need to find one with a seal the correct size.