Ventilation: HRV/ERV

Desired Outcome:

Manufacture specs must be followed at all times.
Ventilation rates must meet ASHRAE 62.2 as calculated using the WAP ASHRAE Calculator or other approved tool.

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.

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.

This method you will install the exhaust side of the unit as you would in the Step 3.
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.

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.

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.

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.

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.

Rigid ducting is recommended; however, if flex ducting is used, it must be UL 181 listed.
Rigid ducts shall not have less than 3 screws equally spaced around the joint.
Flexible ducting shall be fastened with panduit straps tightened with a proper ratcheting tool.
All ducting shall be supported according to SMACN HVAC Duct Construction Standards - Metal and Flexible.
At no time can you reduce the size of the ducting smaller than what the collar is on the appliance.
When or if ducting is being tied into the return air duct system, the proper collars shall be used to ensure a good connection.
The transition duct cannot have any joints within the 8 ft. limit per SWS 6.0202.1a.

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

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 as well as a screen or grill with holes between 1/4" and 1/2 ". Then caulk with an exterior grade caulking.
The transition duct cannot have any joints within the 8' limit per SWS 6.0202.1a.

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.

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.

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.

Using your flow meter, test the suction side of both the exhaust and intake and add the numbers together for total CFM.

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

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 WAP Worst Case Draft Test form.

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