What Is a Fresh Air Intake Vent? A Guide to ERV, HRV & Make-Up Air Systems

If your home or building uses an ERV, HRV, or dedicated fresh-air system, it needs a way to bring outdoor air inside. That starts with a properly selected fresh air intake vent on the exterior of the building.

Choosing the right intake vent matters more than it may seem. The vent needs to allow adequate airflow while helping protect the duct system from rain, debris, insects, and other outdoor elements. In this guide, we'll explain what a fresh air intake vent does, where it's commonly used, and what to consider when choosing an exterior vent for an ERV, HRV, or make-up air system.

What Is a Fresh Air Intake Vent?

A fresh air intake vent is the exterior termination point where outdoor air enters a home's ventilation or HVAC system. Unlike an exhaust vent, which removes air from the building, an intake vent is designed to bring fresh outdoor air into the system.

Fresh air intake vents are commonly used with energy recovery ventilators (ERVs), heat recovery ventilators (HRVs), dedicated outdoor air systems, and some make-up air applications. The intake connects to ductwork that carries outdoor air into the ventilation equipment or HVAC system before it is distributed throughout the building.

Because the vent is exposed to the weather, its design should help limit rain and debris from entering the duct while still allowing proper airflow.

Fresh Air Intake Vent vs. Exhaust Vent

Fresh air intake vents and exhaust vents may look similar from the outside, but they serve opposite functions.

A fresh air intake vent brings outdoor air into the building. An exhaust vent removes indoor air from the building, such as air from a bathroom fan, kitchen exhaust system, or other mechanical ventilation equipment.

This distinction matters because exterior terminations are not always interchangeable. The vent design, airflow direction, screen or pest protection, and intended application should all match the system being installed.

For example, a termination designed for fresh-air intake may be appropriate for an ERV, HRV, or make-up air system, while a dryer exhaust requires a vent specifically suited for lint-producing dryer airflow.

How Fresh Air Intake Vents Work with ERVs and HRVs

ERVs and HRVs are designed to exchange stale indoor air with fresh outdoor air. To do that, the system needs both an exhaust path and a fresh-air intake path.

The fresh air intake vent is where outdoor air first enters the system. From there, the air travels through ductwork to the ERV or HRV, where energy is transferred between the incoming and outgoing air streams before the fresh air is distributed into the building.

Because the intake is the first point of contact with outdoor air, proper placement and vent selection are important. The intake should be located where it can draw in clean outdoor air while minimizing exposure to exhaust outlets, contaminants, and other sources that could affect indoor air quality.

What Is a Make-Up Air Vent?

A make-up air vent provides replacement outdoor air when indoor air is being exhausted from a building. Without enough replacement air, exhaust fans, range hoods, and other mechanical systems can create negative pressure inside the home or building.

Make-up air systems help replace the air being removed so the building can maintain more balanced airflow. Depending on the system design, outdoor air may enter through a dedicated wall vent and then travel through ductwork before being distributed indoors.

Fresh air intake vents and make-up air vents can serve similar purposes, but the required airflow, duct size, controls, and equipment can vary significantly from one application to another. The exterior termination should be selected based on the specific system and airflow requirements.

How to Choose the Right Fresh Air Intake Vent

Choosing the right fresh air intake vent starts with the requirements of the ventilation system. The vent should match the duct size, airflow needs, installation location, and intended application.

One of the first things to confirm is the duct diameter. Fresh air intake systems commonly use 4-inch or 6-inch ductwork, but the correct size should always be based on the equipment and system design.

The exterior vent should also be designed to help keep rain, debris, and pests from entering the duct while allowing air to move freely. Placement matters as well. Intake vents should be located where they can draw in relatively clean outdoor air and should be separated from exhaust outlets and other potential contaminants according to applicable code and equipment requirements.

For ERV, HRV, and make-up air applications, choose an exterior termination specifically intended for fresh-air intake rather than assuming that any wall cap or exhaust vent will work.

FreshVent for Fresh Air Intake Applications

For installations that require a dedicated exterior fresh air intake, FreshVent provides a purpose-built termination for residential and light commercial ventilation systems.

FreshVent can be used with ERV, HRV, and other fresh-air intake applications where outdoor air needs to enter through an exterior wall. Available in 4-inch and 6-inch sizes, it can accommodate common ventilation duct sizes while providing a finished exterior termination.

When selecting a FreshVent, match the vent size to the ductwork and ventilation equipment specified for the system. Always verify the equipment manufacturer's requirements and applicable local codes before installation.

Need a fresh air intake vent for your next project? Shop the FreshVent™ Low-Profile Air Intake Vent, available in 4-inch and 6-inch sizes for ERV, HRV, fresh-air, and make-up air applications.

Where Should a Fresh Air Intake Vent Be Located?

A fresh air intake vent should be located where it can draw in clean outdoor air while staying away from exhaust outlets, vehicle exhaust, plumbing vents, dryer vents, and other potential contaminants.

The exact clearance requirements can vary depending on the equipment, building design, and local mechanical code, so the installation should always follow the manufacturer's instructions and applicable code requirements.

The intake should also be positioned where it is less likely to be blocked by landscaping, snow, debris, or other obstructions. Good placement helps protect airflow and reduces the chance of unwanted contaminants being pulled into the ventilation system.

Fresh Air Intake Vent FAQs

Can I use an exhaust vent as a fresh air intake?

Not always. Intake and exhaust terminations are designed for different airflow directions and applications. For ERV, HRV, and make-up air systems, use an exterior termination intended for fresh-air intake whenever possible.

What size fresh air intake vent do I need?

The vent size should match the ductwork and ventilation equipment specified for the system. Common residential sizes include 4-inch and 6-inch, but the correct size depends on the required airflow and system design.

Do fresh air intake vents need a screen?

Many intake vents include some form of pest or debris protection, but the exact design varies by product. The screen or protective feature should not restrict airflow beyond what the system can accommodate.

Can a fresh air intake be installed near a dryer vent?

Clearance matters. Fresh-air intakes should be located away from dryer exhaust and other contaminant sources according to the equipment manufacturer's instructions and applicable mechanical code requirements.

What systems use fresh air intake vents?

Fresh air intake vents are commonly used with ERVs, HRVs, dedicated outdoor-air systems, make-up air systems, and other mechanical ventilation systems that bring outdoor air into a building.

A properly selected fresh air intake vent is an important part of any ERV, HRV, or make-up air system. Matching the vent to the duct size, airflow requirements, application, and installation location helps the ventilation system perform as intended while providing a clean, finished exterior termination.