Originally Posted By: pdickerson This post was automatically imported from our archived forum.
I inspect quite a few mobile homes with air admittance valves to vent the kitchen and bathroom sinks. I generally don’t comment on these. Should I be?
These valves are supposed to only be used in ventilated areas. The sink cabinets are generally not ventilated, however every mobile home I have inspected is done the same way. Comments?
Originally Posted By: rmoore This post was automatically imported from our archived forum.
“Access and Ventilation. Access shall be provided to all AAVs. The valve shall be located within a ventilated space that allows air to enter the valve.”
Paul...I bolded "enter" because the intent is to let enough air into the valve to prevent a siphon. That is not a lot of air, and unless the cabinets are weatherstripped and absolutely air-tight, I don't see a problem. Any lowered pressure within the cabinet should be easily compensated for through the normal door gaps, no matter how closely fitting the doors are.
The ventilation is not for...well...ventilation  as the valves are designed not to let any sewer gases escape.
In some instances the AAV's are installed using a small in-wall box. I would imagine the code is more to deter covering that small box with an air-tight plate, which would prevent proper function.
-- Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com