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Heat Recovery Ventilation And Energy Recovery Ventilation: What’s The Difference?

A ventilation system for your house is supposed to serve several purposes. The system should push out stale air, while bringing clean outdoor air into your home. This process can help to neutralize odors in your home and cut down on harmful pollutants in the air. Lowering the overall humidity of the home should also be a goal of an effective ventilation system, but it’s not always achieved. The most popular ventilation systems are the heat recovery ventilator (HRV) and the energy recovery ventilator (ERV).Both an ERV and an HRV pull the stale air out of the home and improve air quality. The air being exhausted from the building and the air being pulled inside are two streams that exist within both systems. The ERV and HRV both provide heat recovery ventilation, but they don’t operate with the same guidelines.

In heat recovery ventilation, the heat from the hotter airstream is transferred to the cooler stream without any air crossing between. This puts less work on your furnace during the winter and A/C in the summer and cuts down on heating/cooling costs. The ERV system crosses air between streams, but also provides the transfer of humidity to the drier air stream.  This enthalpy transfer works as a humidifier or de-humidifier for your home, depending on the season.


On paper, ERV ventilation provides more value to the consumer. But will cross-leakage cause dirty air to circulate back into the home? That depends on where the exhaust air is coming from. The Air Conditioning and Refrigeration Institute (ACRI) has a regulation covering the exhaust air transfer ratio (EATR). When so-called Class 2 air from a bathroom or locker room is transferred to a Class 1 space, it can only make up 10 percent of the air streamed. The other 90 percent must be fresh outdoor air, meeting the higher standard for Class 1 air. The ACRI regulation for Class 3 air drops to 5 percent.

For questions about mechanical ventilation systems, please contact us at Wolff Mechanical. We’ve been serving the Greater Phoenix area for the last 22 years with an A-plus rating through the Better Business Bureau.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems). 

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