How To Look At A House

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Can an air admittance valve (AAV or Studor) be installed horizontally?

Tuesday, February 1, 2022

Manufacturers specify that an air admittance valve be installed within 15º of vertical. So the sideways installation shown above is not acceptable, and it will not function properly in that position. The International Residential Code (IRC) and Residential Edition of the Florida Building Code (FBC) further specify that an air admittance valve be located a minimum of 4-inches above the horizontal branch drain (trap arm) of the fixture being vented (FBC 3114.4).

    Also see our articles What is an auto vent, air admittance valve, or check vent? and How many plumbing vents through the roof are required by code? and Is an air admittance valve (AAV) legal by code? and What are the code requirements for plumbing vent terminations? 

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Here’s links to a collection of our blog posts about PLUMBING DRAINS AND TRAPS:

Why can't a sanitary tee be used for a horizontal-to-horizontal drain pipe connection? 

 Why is it a problem when a trap under a sink is installed backwards?  

What are the code requirements for layout of drain piping under sinks?

 What is the difference between a vent stack and a stack vent?

What is a "combination waste and vent" in a plumbing system? 

• Why is garbage disposal not allowed at a combination waste and vent (CW&V) under a sink? 

What is an indirect waste receptor? 

What is the difference between water pipe and sewage (waste) pipe? 

How can I tell if a house is connected to a septic tank system or sewer?

Is a sink required to have a drain stopper? 

How far away from the sink can I install a dishwasher? 

• What is the minimum and maximum distance a P-trap can be below a sink?  

• What is a double trap in plumbing? 

• Can two sinks share a trap? 

• Does a home inspector check sewer lines underground? 

• What types of plumbing traps are illegal by code? 

• What is the minimum and maximum slope of the trap arm of a plumbing drain? 

     Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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