Replies

1. 
   DCContrarian | Jul 22, 2021 11:39pm | #1

   I never thought of it as an energy saving device, it's usually used to avoid inconvenient pipe runs.

   They do go bad. If they stick in the open position sewer gas gets into your house and it smells like something died under the sink. It's important to put the valve where it is accessible, it's simple to screw off the old one and put on a new one, it's about as hard as changing a light bulb.

   I wasn't familiar with the Magic Vent brand so I googled it, it's a trap with a fitting for the vent already attached. I could see the appeal of that, it saves having to glue up a tee, but often space under a sink is tight and you need to get creative routing the drain. I think in a lot of cases the Magic Vent wouldn't fit.

2. Expert Member
   BILL WICHERS | Jul 23, 2021 09:24am | #2

   Even when using AAVs, you still need at least one main vent going outside. You can't use AAVs exclusively.

   Note that with very long runs of pipe, there is very little air exchange between the "ends" of the pipe unless an outside force is involved (a pressure differential). I wouldn't consider a stack vent an air leak for this reason, and there shouldn't be lots of air moving in there all the time acting to keep the pipe hot or cold. You'll see some conducted heat near where it exits the home, but as you go further along the line, the temperature will even out.

   I don't think an AAV instead of a regular, plumbed vent to outdoors is going to make an significant impact on the overall energy use of a house.

   Bill

3. 
   walta100 | Jul 23, 2021 01:05pm | #3

   Before you buy any make sure your local inspector will approve AAV they are still not allowed everywhere.

   Walta

4. 
   Malcolm_Taylor | Jul 23, 2021 02:53pm | #4

   "A plumbing vent has no connection to the interior air of a home, so there shouldn't be any air leakage associated with a traditional plumbing vent, as long as the penetration is properly sealed. There will be some conduction losses through the PVC or ABS pipe, but these conduction losses aren't very significant."

   -- Martin Holladay

5. 
   PAUL KUENN | Jul 23, 2021 10:05pm | #5

   Thanks all! Client asked and wanted just a bit more than my persuasion. Glad you all agree that they are not worth the problem of installation.

1. Expert Member
   BILL WICHERS | Jul 23, 2021 10:21pm | #6

   I only use AAVs where it's difficult to put in a "regular" vent. This usually means places like kitchen islands and the ocassional bathroom vanity. I prefer to use regular "plumbed to outdoors" vents everywhere else, since there is very little to fail with a piece of pipe that is open on the far end :-)

   Bill

1. 
   Malcolm_Taylor | Jul 23, 2021 11:31pm | #7

   Unless something has changed recently, our code limits them to kitchen islands, and in that situation I still prefer a Chicago loop.