ERV or HRV: Which system best suits your home?
Homeowners looking to increase whole-house ventilation rates — ensuring that air exchange between the indoors and outdoors leads to improved indoor air quality — often find themselves deciding between the heat recovery ventilator (HRV) and the energy recovery ventilator (ERV). Both systems provide a means for fresh outdoor air to enter the home, while exhausting allergen-laden indoor air. However, the systems differ in one significant way: humidity control.
The benefits of recovery ventilators
Recovery-ventilation systems boost air exchange in airtight homes, simultaneously supplying equal amounts of fresh air sourced from the outdoors and exhausting air inside the home, which generally contains high concentrations of pollutants.
This process offers homeowners who use them several key perks:
- Energy recovery. While the HRV and ERV operate, they capture energy in the outgoing supply of air and then use that energy to precool or preheat the incoming air. Without this recovery function, these ventilators would cost a fortune to run.
- Air quality control. With equal amounts of air exchange, an HRV or ERV boosts air quality inside your home. This is particularly true of airtight and well-insulated homes.
The ERV set apart
ERVs offer a distinct benefit that HRVs don't: humidity control. As the energy recovery ventilator pulls and pushes air into and out of the home, it also manages water vapor in the process.
In the summer, when outdoor humidity levels are high, using an HRV may result in high amounts of water vapor entering the home. This increase would cause homeowners to run their air conditioners more often and drive up energy costs. The ERV solves this problem, removing moisture before it enters the home and thus controlling air conditioning costs.
The ERV also controls humidity in the winter. Exhausting the home of air also removes any moisture that's generated inside the home, leading to an uncomfortably dry home. To counter this effect, the ERV strips moisture from the outgoing supply of air and restores it to the home through the incoming air.
Criteria that dictate your purchase
Choosing between the HRV and ERV involves looking at a few key criteria to help you make the best decision possible to meet your home's ventilation needs.
- Your climate. In general, homeowners living in a heating-dominant climate do better with an HRV because controlling humidity in summer is not a relevant factor. To counter dryness, homeowners can run their HRVs on lower speeds or adjust the controls to deliver intermittent operation. Homeowners in cooling-dominant climates often require the use of an ERV.
- Air conditioning. If your home doesn't currently include central air conditioning, a ventilation system won't make sense in the summer. Both systems rely on cooled indoor air to precool incoming air. Without central A/C, the ventilator won't have the advantage of energy recovery, and operating costs would generally be prohibitive.
- Humidity control. In homes with high moisture levels, whole-house ventilation can make sense, especially if the house is airtight.
- Mixed climates. If you reside in a climate that requires equal amounts of heating and cooling, either system can work. The choice depends largely on the airtightness of your home and how much moisture is present.
If you're facing a buying decision and trying to choose between a heat recovery ventilator and energy recovery ventilator, talk to a professional to help you accurately assess your home's needs to find the right solution to ventilation, energy efficiency and comfort.