Unique plumbing issue in a 300-400 year old house

[Basher]

Wouldn't the positive pressure need to come from behind the flow?

The positive pressure I'm referring to comes from other users elsewhere on the system, or from a pumping station. If you are miles from other houses, and from underground equipment on the system, this is probably a red herring.

 

[cloudsix]

The positive pressure I'm referring to comes from other users elsewhere on the system, or from a pumping station. If you are miles from other houses, and from underground equipment on the system, this is probably a red herring.

Interesting!

One thing I noticed is the shower tray trap cover doesn't have a tight seal, so I've ordered a new one. Hoping it fits.

If that fails, I'll give the outside cover a nudge.

Appreciate your thoughts.

 

[Ric2013]

The open pipe stuffed with a rag is a smoking gun. If your drains aren't airtight, then that really is the most likely cause of sewer gasses coming into the house. No point having a load of traps and one-way valves if the pipe is left open (and blocked with a rag).

Until you've capped that pipe in an airtight manner (whether with a proper cap or a rubber glove/gaffer tape as has been suggested), looking for additional causes is likely to be only a waste of time and money.

 

[cloudsix]

The open pipe stuffed with a rag is a smoking gun. If your drains aren't airtight, then that really is the most likely cause of sewer gasses coming into the house. No point having a load of traps and one-way valves if the pipe is left open (and blocked with a rag).

Until you've capped that pipe in an airtight manner (whether with a proper cap or a rubber glove/gaffer tape as has been suggested), looking for additional causes is likely to be only a waste of time and money.

Are you suggesting that part not being airtight in the cellar could cause the smell from a different room 2 floors up?

 

[Ric2013]

Are you suggesting that part not being airtight in the cellar could cause the smell from a different room 2 floors up?

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!

 

[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.