My frontloading washer seems to siphon the traps dry on my shower drain, both the laundry sink and regular sink when the washer drains, I think as the sewer gas fills the room. Was told to get a antisiphoning valve which I did but I'm unsure of how and where to mount it?

That is usually caused by inadequate venting and/or poor design installation. The water flows past the other drains and there is no makeup air from a vent, the plumbing is venting through the traps. Make sure the roof vents are not plugged, I have seen them full of acorns! Has it always been like this or were changes made in the plumbing?

Exactly where does your washer drain to?

Show us this antisiphoning valve that you purchased. There are anti-syphon valves for water supply lines. Never heard of a anti-syphon valve for drain.

An AAV might be in order here. The only reason a washer drain could cause this is if we're tightly sealed in a drain tube stand pipe. Breaking that possible seal would allow air to enter the drain.

Hi Bill

Is this a new issue? If it is, then my guess is that you have a venting issue much like ma0614 suggested.

I would also like to see this siphoning valve as Hkstroud requested.

If it an ongoing issue then you certainly made need to consider the AAV as suggested by ballengerb1.

Back to you...

Mark

antisiphoning valve

Bet this is an AAV.