advice on basin waste

[dave78]

I have recently converted a storage room upstairs into a very small cloakroom consisting of WC and wash basin. I opted for a saniflo (WC only) as getting a soil pipe would have meant getting up many floor joists.
The waste setup is an anti vac trap on washbasin then 32mm running vertically downwards 50cm and then elbowing into a 3.5m run of 32mm outside.
From saniflo 32mm runs approx 50cm vertically down and then tees into the horizontal run of 32mm from the washbasin. Slope complies with manufacturers guides and the tee has been put in to direct water away from the sink.
The problem is Im getting siphoning when the saniflo operates. Major gargling occurs at the washbasin and water is pushed out from the trap.

A plumber friend advised to try an AAV near sink trap..and to replace the trap to an anti vac one. The problem has reduced but water is still pushed out of the basin trap and gargling noises are still heard.

Will a hepvo sort my issue out ...Im assuming the water coming up at the sink is that stored in the bottle trap.

Thanks in advance

 

[Bahco]

Never done anything with a Saniflo but presume the principle is the same and you need to vent to stop siphonage.

Suggest you play around with AAVs etc until it stops.

You could always get rid of the Saniflo !

 

[blondini]

Sounds like positive pressure causing the gurgling, not vacuum, and a Hepvo will stop this. But is the design of your waste sound? I think the basin waste diameter is really too small for the length of run and just teeing in the waste from the saniflo is probably a complete no no. I'm not a pro, so wait for me to be shot down in flames

 

[Bahco]

Rereading you should not have teed into Saniflo waste pipe. Redo taking the new waste directly to the stack and use a anti vac trap.

You may need an extra AAV if your run is exceeding 1.7 metres.