I'm surprised that in a gut remodel accommodations couldn't be made for proper venting. Or did they just forget?

Even if they did forget, I'm not up on plumbing code anymore, but you used to be able to wet vent 60" laterally with 2" drain pipe.

An air admittance valve is going to leak water every time the water is turned on or off? I've NEVER seen one leak water when properly installed.

That said, I've seen the valves hidden in adjacent closets. I've seen the valves run up an interior wall, and then a little "medicine cabinet" type of enclosure was built to house the valve. The door to the cabinet can be made to look like a painting or photo hung on the wall. Sort of like a hidden compartment. Easy to do.

The valve does need to be accessible so it can be replaced if needed. The higher above the waterline of the tub you terminate the valve, the less likely you'll ever see water dribbling out of the valve. And again, water should never exit the valve unless there is multiple failure. Clogged line, the valve flapper fails, etc. Any backup within the tub's drain line itself should backup and exit out of the tub's overflow before it ever reached the height of the valve.

If you do bring the valve out of the tub deck, then disguise it with a small enclosure that slips down over the top of the valve and its standpipe.

mongoct,

Thanks for your prompt reply! Encouraging words. The valve is called an atmospheric vacuum breaker, it is a Watts model #288A anti-siphon vacuum breaker. It is supposed to be installed in the hot/cold supply line to the tub filler rather than the tub drain. I believe the valve is suppose to prevent any chemicals from being siphoned back thru the pipes into our water supply. The instructions say; "...device can spill water, install where spillage is not objectionable." I like the idea of mounting it higher and in-wall behind a small picture. Perhaps in a plastic box with a drain through an outer wall.

*sigh* I know it is for our protection that we have all these rules and codes...

Rhodeback

Stop the train!

In your original post I took the "anti-siphoning" valve to mean that your tub wasn't vented and they were installing an air admittance valve. You were talking apples and I was envisioning oranges.

Who is telling you to install this? TheGC? Plumber? Building Inspector?

That Watts valve is a backflow check valve, or as you wrote, an anti-siphon valve. It's designed to prevent water from being siphoned from the tub, backwards up into and through your tub's faucet, and into your house's copper plumbing supply lines.

You would only need something like that if the outlet of your faucet was below the level of water when your tub is full...which would have to be below the height of the tub's overflow valve. When you fill the tub will the mouth of the faucet actually be underwater? That's when you'd need an anti-siphoning valve.

Now I'm no plumber...but this has me scratching my head.

Lazypup? Are you out there to answer this one?

All aboard! Everyone back on the train!

It's a good night for me, not only did the Red Sox beat the Jays, but it was a home run fest, even for Ortiz.

But it might be a semi-bad night for you. I took a look online at the Geberit filler. And whaddaya know, the tub filler is integrated in the same housing with the tub overflow, which does indeed put the filler spout inside the tub at bathwater level.

I have to say that's a new one on me. I've never seen that design before.

With this design, since the fill spout could easily be in contact with the bath water, you will indeed need that anti-siphon valve to prevent bath water from being siphoned back into the supply lines.

I highly recommend that you and your builder...but you for certain so you can hear it with your own ears...call Geberit tech support and ask about the Watts valve and a practical place to install it. And just how much water does it shed? And what are their recommendations for containing that water?

They are just outside of Chicago, the tech support number is 1.800.TECTRUE

Would you mind providing follow-up when you hear back and when the installation is done? I'd love to see photos.

Best (and good luck), Mongo

Thanks again mongoct...it's making more and more sense. I got that particular Cascading tub filler with integrated overflow because I wanted to *minimize* the amount of fixtures as much as possible...hahaha...jokes on me now that I have to *add* the anti-siphoning valve. The instructions for the Gerberit install indicated that the anti-siphon valve was required...and duh...thanks for pointing out about tech support. So obvious...I completely whiffed on it... I will call Gerberit tech support, but I think your idea of hiding it behind a small picture or framed painting is outstanding.

Rhodeback

I have to modify that idea a bit, for when I thought it was a drain-waste-vent air admittance venting valve, that would be easy to run into and up a wall and hide behind framed artwork.

With this valve being part of your water supply line it sort of changes things a bit.

But yes, perhaps you could have it come up through the tub deck and fashion a small bottomless cube-shaped box to sit right on top of the valve, thus hiding it in plain site.

That's a slick looking valve, though.

i looked into this several years ago and installed one.

It has an antibackflow already in it.

Call Chicago Faucet.

They are all good on the phone and they know everything.

HTH