Cheater Valve Used for Venting. This is a common issue that I have often wrote about as it confuses some Home Inspectors. Cheater Valves, a.k.a. air admittance valves are addressed by the Ontario Building Code and may be used when installed in compliance with the code. Your local municipality may restrict the use of “cheater valves” and it is recommended that you check with them prior to installing one.

2.5.9. Air Admittance Valves
(See A-2.2.10.16.(1) in Appendix A.)

2.5.9.1. Air Admittance Valve as a Vent Terminal

1) Individual vents may terminate with a connection to an air admittance valve as provided in Articles 2.5.9.2. and 2.5.9.3. (See also Sentence 2.2.10.16.(1).)

2.5.9.2. Air Admittance Valves

Cheater Valve Installation1) Air admittance valves shall only be used to vent
a)fixtures located in island counters,
b)fixtures that may be affected by frost closure of the vent due to local climatic conditions,
c)fixtures in one- and two-family dwellings undergoing renovation, or
d)installations where connection to a vent may not be practical.

air-admittance-valveAir admittance valves shall be located
a)not less than 100 mm above the horizontal branch drain or fixture drain being vented,
b)within the maximum developed length permitted for the vent, and
c)not less than 150 mm above insulation materials.

2.5.9.3. Installation Conditions

1) Air admittance valves shall not be installed in supply or return air plenums, or in locations where they may be exposed to freezing temperatures.

2) Air admittance valves shall be installed in accordance with the manufacturer`s installation instructions.

3) Air admittance valves shall be rated for the size of vent pipe to which they are connected.

4) Installed air admittance valves shall be
a)accessible, and
b)located in a space that allows air to enter the valve.

5) Every drainage system shall have one vent that terminates to the outdoors in conformance with Sentence 2.5.6.2.(1).

Note: If you meet the conditions required by Ontario Building Code and Municipality it is important to ensure your valve is CSA approved.

If you are selling your property and a home inspection report details a list of deficiencies, sometimes it is in your best interests to do some research into some of deficiencies noted. I have received the odd gift from home owners who have been requested to make some expensive repairs prior to selling home, when in fact they were not required. An in-experienced home inspector can cost both the buyer and seller money.