Every tightly sealed home should contain mechanical ventilation equipment to exchange stale indoor air with fresh outdoor air. This helps remove odors, dilute contaminants and maintain optimal humidity for healthier indoor air. An equal exchange rate results in balanced home ventilation, which is superior to exhaust-only or supply-only ventilation.
Now the question is which type of system is right for you, a heat-recovery ventilator (HRV) or an energy-recovery ventilator (ERV)? To help find the answer, you need to learn more about each ventilation system.
Heat-Recovery Ventilation
With this option, stale air is removed (usually from the bathroom, laundry room and kitchen), while fresh air is vented into the bedrooms and living room. Both air streams pass through the HRV to transfer heat to and from the outgoing air, depending on the season.
The air streams don’t mix, but the heat is “recovered” to improve system efficiency. This is the biggest difference between an HRV and simply opening a window.
Energy-Recovery Ventilation
An ERV works the same way as an HRV, but in addition to transferring heat, an ERV also transfers moisture to and from air streams. The cross contamination rate during moisture transfer is often 10 percent or lower.
Which One is Better?
At quick glance, it seems that ERVs are superior because of their moisture-transferring ability. However, upon closer inspection, it’s clear that climate plays an important role. For example, in a hot, humid climate, indoor humidity may actually rise above exterior levels, which can only be exacerbated by an ERV.
Indoor humidity, home tightness and occupancy level are all concerns of most homeowners, especially in Minnesota’s cold, dry climate. Here are some guidelines to help you make the right choice:
- If you have a small, tight home and a large family, choose an HRV.
- If you have a large home and fewer occupants, choose an ERV.
While it’s easy to over think your decision, the good news is that you can always adjust indoor humidity by changing the ventilation rate. For more help choosing which home ventilation system is best for your needs, contact Marsh Heating & Air Conditioning in the Twin Cities metro area.
Our goal is to help educate our customers in Minneapolis-St. Paul, Minnesota about energy and home comfort issues (specific to HVAC systems). For more information about home ventilation and other HVAC topics, download our free Home Comfort Resource guide.
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