Gurgling shower trap

[Adam]

Hi

I’ve just installed a new bathroom but when emptying the bath or the sink the shower trap gurgles. The water in the trap also moves when the toilet is flushed but it does not gurgle.

I’ve read the DIY project on ‘Gurgling basins’. Can I install an air admittance valve on the pipe leading to the shower trap? The only problem is that the air vent will be at the same level as the shower trap, will this still work? Or would it be better to install this under the sink which is the highest point?

Sometimes the bath gurgles too; do I need to install an air vent on the bath too?

The sink has an anti-vac bottle trap. The waste pipes are all 40mm apart from the last meter up to the sink which is 32mm.

The old bathroom did not have a shower but the bath was (and is) slow in draining

Thanks for your help

[thedoctor]

If the shower tray and the basin are on the same run, one valve will do the job. The pipe should be cut into as shown in the project and the valve inserted as we have shown. The gurgling occurs because the flow of water is causing a vacuuum behind it and trying to suck water out of the trap. If an air admittance valve is installed only air is sucjked in leaving the traps full of water.

[Adam]

Hi

Thanks for the reply. Does it matter where I install the valve? Is it ok under the shower tray next to the gurgling trap?

Or is it best high up?

Thanks
Adam

[Adam]

Hi
I've installed an air admittance valve under the sink but when water drains from the sink I still get gurgling & spitting from the bath waste?

Is it a air flow problem with the soil stack?

Thanks
Adam