1. Determine appliance location

• Location selection must comply with manufacturer specifications.

• The location will be determined by the ability to run ducting to proper locations and easy access for routine maintenance.

• The unit shall not be installed in a space that will fall below 32 degrees Fahrenheit.

2. Determine intake & exhaust locations

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

• The intake cannot 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.

• Exhaust- Shall be located at least 6' away from the intake unless mentioned otherwise in manufacture specifications.

• Both exhaust and intake shall be located 18" above the exterior grade.

3. Determine system configuration

• Steps 3a-3c list the different methods of installation.

3a. Option #1- Exhaust at source and supply in return

• This method you will install the exhaust side of the unit as you would in the Step 2.

• However, the supply will be tied into the return ducting on the HVAC system.

• This will allow for even distribution of fresh air throughout the entire home.

3b. Option #2- Exhaust and supply in return

• Though this method is available, it is not recommended.

• This method is only effective while the fan on the furnace is in operation. If the fan were to be shut off, the intake and exhaust will circulate inside of the ducting and not properly vent the home.

• To install this method, the supply is done the same as in Option #1, and the exhaust is installed at least 6' upstream from the exhaust in the return ducting.

3c. Option #3- Independent System

• Install register boots or diffuser boxes in the locations you want air to be supplied to and exhausted from.

• The number of boots needed for both supply and exhaust will be determined by the CFM of the HRV/ERV and allow it to run quietly.

• This method should only be considered when there is no existing ductwork for the mechanical system.

4. Mount appliance

• Mount appliance according to manufacture instructions.

• Hanging the appliance from the ceiling has less vibration noise transfer than, for instance, a solid mount to a wall.

5. Drill/Cut exterior penetrations

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

• Vibration isolation should be considered when piping or ducting passes through solid framing members.

6. Install ducting

• Follow steps as shown on all parts of Ventilation: Exhaust Fan steps 4-4d to install ducting.

7. Support duct

• Support rigid ducts every 10' or less using 1/2" or wider material.

• If flexible ducting was allowed as described in step 4 of Ventilation: Exhaust Fan, it must be supported every 4 feet or less with a minimum of 1.5 inch wide support material. This support ensures the duct remains fully extended, preventing kinks and airflow restrictions. Additionally, the duct should not sag more than 1/2 inch per foot between supports and should maintain a bend radius of at least one duct diameter to avoid restricting airflow.

8. Seal ducting

• All ducting must be sealed with a mastic or tape with a UL 181 rating.

• Reference the Air Seal Duct section of this field guide.

9. Insulate ducting

• Any rigid ducting between the exterior intake penetration and the unit must be insulated, along with any ducting that is outside of the conditioned area to a minimum R-8.

• See the Duct Insulation section of this field guide.

• If the ducting is a flexible duct that is already an R-8, this step does not apply.

10. Install terminations

• Intake- Install a fixed louvered intake cover that has openings no smaller than 1/4" and no larger than 1/2". Then caulk with an exterior grade caulking.

• Exhaust- Install a louvered exhaust vent or vent hood. Then caulk with an exterior grade caulking.

11. Install condensation

• Run the condensation line to a drain or condensate pump and discharge in an approved method.

• Be sure to loop the condensate line near the unit, creating a condensate trap to prevent foul odors from entering the unit.

12. Install controls

• Many units have built-in controls. If not, you may need to install a control to give you the operation that you need.

• With many styles of controls available, find the one that best fits your needs and install according to manufacture specifications.

13. Install electrical

• Many units come with a power cord that can be plugged in.

• If needed, have an electrician install an outlet near the unit so the cord can reach.

14. Test flow

• Using your flow meter, test the suction side of both the exhaust and intake and take the average flow by adding the numbers together and dividing by two for total CFM.

15. Client education

• Educate the client on how the system operates, adjusts, and how to clean and maintain the filters.

16. Worst Case Draft test

• Conduct a Worst Case Draft (WCD) 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.

Manufacture specs

• Manufacture specs must be followed at all times.

• Ventilation rates must meet ASHRAE 62.2 as calculated using the Utah WAP ASHRAE Calculator or other approved tool.