I have a general question about air admittance valves versus through the roof sewer vents. Do air admittance valves exactly perform the same function as through the roof vents? In other words, if I install these valves at all the critical places, could I completely eliminate all through the roof vents?
Thanks,
Richard
Richard,
Air Admittance Valves (AAV) are one-way vents installed after the trap on the drain line of a fixture. They're designed to address negative air pressure in the drain system, created when a fixture is drained.
a traditional, passive, external venting system will always be superior (especially when it comes to positive pressure)
No. Consider the total system. A properly designed roof vent will create a constant slightly negative pressure in the holding tank. Air admittance valves admit fresh air to the tank in response to negative pressure. Same when you flush the toilet. Interior air goes down the toilet - odors go out the (2-way flow) roof vent. We turn OFF the bathroom vent fan when flushing to avoid "reversing the direction of black tank air flow".
Photos below: 1. Foretravel OEM Vac-U-Jet venturi vent 2. Camco Cyclone vent 3. Lippert "360" Siphon vent
Thanks guys. These two posts answer my question.
Richard
Cyclone vent or lippert vent. Which is the best and the most used?
Peter
I think the 360 works well for me. Always have a negative pressure on the tank IE no smells and no moving parts
I replaced the OEM (venturi) vent with a Cyclone 6 years ago. Other than turning yellow from UV exposure, it has held up well. It still rotates freely in the slightest breeze, and keeps our holding tanks odor-free.
NOTE: Our (GV) roof is flat, hence the Cyclone vent is mounted in a fairly vertical position. On a curved (Unicoach) roof, the Cyclone may not rotate as freely due to being mounted in a slightly tilted position. The Lippert 360 might be a better choice? I don't know - I've never tried one.
I like the Cyclone vents. If I hear them rattle in the night, I know to put the awnings away before the wind gets 'em.
This has been my experience now on several different rvs. I definitely prefer the Lippert 360.
What is broken on the roof? (https://www.foreforums.com/index.php?topic=43282.msg435404#msg435404)