fill my sink and let it drain – the water comes up in the shower – its lower and it preferentially going there instead of the waste stack – – but drains away slowly while gurgling through the sinks u bend.

I’ve had the inspection cap off the Stack T piece and looked into the waste pipe with no sign of blockages

i think i have 2 issues here – one the old geezer hasn’t fitted a trap to the shower – hes just got the drain straight into a 90degree bend – so will sort that.

second – i need a air admittance valve somewhere -terminating higher than the highest u bend(sink) . – but does it go between the shower and sink wastes or after the sink waste (the system is – shower – sink Tee’d into the shower waste – vented soil stack does it matter *

where does one get an air admittance valve ? would an anti vac trap be what i want ? or would an anti vac u bend trap on the sink alone do the job ?

*i accept that i may well flood my house if i get this wrong but at least my neighbours wont be harmed in the doing so 😉

Simplest thing is to try an anti vac trap on the sink first.

Will probably cure it to be honest.

cheers – that is the easy route as everything else is destroy bathroom time and im reluctant to- we have lived with it for 18 months and a new bathroom is imminent as soon as we get the hall finished – realistically thats 6 months time – and mrs T-R to be snapped last week , shes had enough for the non draining shower

antivac traps stopped the shower from syphoning the sink water due to utubing but its still gurgling for air while draining.

phoned a plumber mate this morning and he said AAV on a on the end of a flexy hose T’d into my 32mm piping – stick it in the air higher than the U bend(now the anti vac trap) and that should solve it.

how fun.