AboutDana Bostick Expertise Pretty much any residential plumbing questions. Note: I live and work in Southern California. We do not as a rule use boilers, hot water or steam heating systems or wells so my knowledge in those areas is limited. There are others here that can probably answer those questions better.
"We all is city folk" out here! What is a "well" LOL
Experience Licensed General Contractor with Plumbing, HVAC and Electrical sub-licenses
Question QUESTION: I realize that I will have to run a 4" drain (and in my case tie into the main drain running below grade outside the house), and have done such an installation before.
In my present home, there was no plumbing at this level, so tying into an existing stack vent is a big deal (Natch, there is not an obvious choice among the baths, laundry above).
Is an Air Admittance Valve (AVV) permitted in unincorporated Los Angeles County for a toilet/shower sink installation?
Fred
ANSWER: Hi Fred,
Ultimately, this depends on what Code is in force and being followed in your area. Check with the LA County Building and Safety.
Per the 2006 International Plumbing Code:
Section 905 - Vent Connections
905.1 - Connection
All individual, branch and circuit vents shall connect to a vent stack, stack vent, air admittance valve or extend to the open air.
Section 917 - Air Admittance Valves
917.1 General
Vent systems utilizing air admittance valves shall comply with this section. Individual-and-branch-type air admittance valves shall conform to ASSE 1051.
917.2 Installation
The valves shall be installed in accordance with the requirements of this section and the manufacturer's installation instructions. Air admittance valves shall be installed after the DWV testing required by Section 312.2 or 312.3 has been performed.
917.3
Where permitted. Individual, branch and circuit vents shall be permitted to terminate with a connection to an air admittance valve. The air admittance valve shall only vent fixtures that are on the same floor level and connect to a horizontal branch drain. The horizontal branch drain shall conform to Section 917.3 or Section 917.3.2.
917.3.1
Location of branch. The horizontal branch drain shall connect to the drainage stack or building drain a maximum of four branch intervals from the top of the stack.
917.3.2
Relief vent. The horizontal branch shall be provided with a relief vent that shall connect to a vent stack, or stack vent, or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the stack air building drain and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 916.2 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.
917.4
Location The air admittance valve shall be located a minimum of 4 inches 9102 mm) above the horizontal branch drain or fixture drain being vented. The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed a minimum of 6 inches (152 mm) above insulation materials.
917.5
Access and Ventilation Access shall be provided to all air admittance valves. The valve shall be located within a ventilated space that allows air to enter the valve.
917.6 - Size
The air admittance valve shall be rated in accordance with the standard for the size of the vent to which the valve is connected.
Hope this helps.
Dana
---------- FOLLOW-UP ----------
QUESTION: Thanks Dana,
Not sure I understand the code language. Seems like a "free-standing" use of the AAV would not be allowed--ie., on a floor w/o any vent stacks. Stated otherwise, it appears that use of the AAV is for situations when one is too far away for a code-specified tie-in to an existing stack, but the drain is nonetheless connected to other portions of the drain system that are properly vented. Kind of belt and suspenders --the AAV is "backed up" by a vent stack (albeit one that is not in the close proximity required w/o the AAV).
So I need to tie in to an existing vent (not drain), as there are no existing drains (or vents) on this floor.
Right?
Fred
Answer LOL, welcome to my world! Try reading the electrical codes sometimes. that's a real snoozer!
I think they mean that the new waste needs to be tied into an existing VENTED waste line so that the existing drain will not need or try to vent through the AAV.
