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HRV/ERV Maintenance

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    Harry Whitver

    Problem

    Below-Peak Performance
    HRVs and ERVs are designed to deliver a controlled amount of fresh air into the house through the central heating and cooling system, regulate air pressure in the house, exhaust stale and dirty air, and exchange the heat of exhausted air to the incoming fresh air to reduce the burden on the heating or cooling equipment. Any number of issues can hinder that performance and render an HRV/ERV ineffective.
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    Harry Whitver

    Solution

    Check the Connections
    Inspect the unit for loose and/or misconnected intake and outtake (or exhaust) lines per the inlets and outlets on the unit. Also look for kinks or clogs in all lines, especially the return-air and exhaust ducts that carry dirt and pollutants. Make sure the fresh-air intake is at least 4 feet away from the exhaust air outlet, and also away from car exhaust, combustion appliance vents, and trash receptacles.
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    Harry Whitver

    Solution

    Clean the Filter
    Like most fans and blowers, an HRV/ERV has a filter that needs to be cleaned periodically to perform properly, whether by a qualified service contractor or the homeowner. Simply remove the front panel to expose the filter and take it out. Most can be cleaned with a gentle application of soap and water. Blow out the system (and all HVAC ducts) at least biannually to remove stubborn debris.

The newest version of the federal Energy Star Qualified Homes program calls for a specific level, or exchange rate, of fresh-air ventilation to help mitigate indoor air problems in the tightly built homes that meet the new standard (see ASHRAE 62.2-2007), if not precisely how builders should achieve those levels. National green building certification programs follow a similar route.

A number of options exist, but an increasing number of builders are turning to heat and energy recovery ventilators (HRVs and ERVs, respectively) to deliver a controlled amount of fresh air in a whole-house scheme as opposed to installing several spot or local ventilation products.

While the air-quality contribution of an HRV or ERV is largely speculative and anecdotal, the units are rated by the Home Ventilating Institute and others for their energy recovery benefits and, in the case of ERVs, a measure of dehumidification.

Assuming, of course, that the units are properly installed and maintained over time. As relatively new products, HRVs and ERVs require their own attention to detail to perform as designed to reduce energy use and costs while delivering fresh air to the interior environment. Here’s how to troubleshoot common problems and educate your home buyers about maintaining the system.

For more construction technology articles, go to www.builderonline.com/construction.