1. Determine intake location

• Locations shall not be located within 10' of property lines or other buildings.

• Intakes can not be located within 10' horizontally from any hazardous or noxious contaminant sources such as combustion appliance vents, driveways, streets, alleys, or parking lots unless they are located 25' vertically above such locations.

• Penetration should be at least 18" above grade or higher as necessary to prevent obstruction.

2. Determine pipe/duct size and design

• Run in the most direct route to exterior.

• Size pipe to the CFM requirements determined from the ASHRAE calculations.

• Changes in direction reduces the total CFM potential and pipe size might need to be increased.

3. Drill/Cut exterior penetration

• Drill or cut a large enough penetration for the pipe or ducting to fit into.

• Reference cutting holes in the Ventilation: Exhaust Fan Section

4. Drill/Cut penetration into HVAC system

• Drill/cut into the return of the HVAC system as close to the blower as possible upstream from the filter ensuring the outside air passes through the filter.

5. Install damper and ducting

• Install the damper as close as possible to the exterior penetration and while maintaining access to the damper.

• Attach the ducting between the damper and the return air penetration.

• Ducting needs to be constructed of a minimum 26 ga.

6. Seal intake ducting

• Seal intake ducting with mastic or foil faced butyl tape.

• See Air Seal Duct section in this guide

7. Install wiring

• Wiring is specific to the control that will operate the damper.

• Read control installation manual for wiring methods.

• Most dampers and controllers use a low-voltage system.

8. Install controller

• There are many different controllers that are available. Install the one that best fits your system.

• Controller needs to ensure operations to ASHRAE 62.2 standard.

9. Install insulation

• Insulate any ducting that is between the exterior penetration and the damper to a minimum R-8.

• See Duct Insulation section in this guide.

10. Install termination

• Install a fixed louvered intake cover that has openings no smaller than 1/4" and no larger than 1/2".

• Then Caulk with and exterior grade caulking.

11. Client Ed

• Educate client on when it will allow air into the HVAC system and how it functions.

12. Worst Case Draft

• Conduct a Worst Case draft test to verify Category I, II, and III appliances are venting safely before leaving home for the day.

• Testing shall be recorded using the Utah WAP Worst Case Draft Test form.