Launch Slideshow

Recovery Time

10 heat-recovery ventilators and energy-recovery ventilators.

Recovery Time

10 heat-recovery ventilators and energy-recovery ventilators.

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    Dan Walbridge

    Trane. The FreshEffects ERV achieves up to an HVI-certified 78% heat recovery efficiency using a high-performance, permanently lubricated ball-bearing motor and a plate energy transfer core with humidity control. Filters slide out for easy cleaning and maintenance. The heavy-gauge, powder-painted steel cabinet features closed-cell gasketing for insulating value and placement in unconditioned spaces; the cabinet design allows various installation options. Adjustable controls enable automatic ventilation. 903.581.3660. www.trane.com.

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    Carrier. Performance Series ERVs (pictured) and HRVs achieve 84% recovery and exchange efficiencies. Cross-flow (or counterflow) heat exchange cores ensure no mixing of the incoming and exhaust air. The units also feature a pre-filter for incoming air, automatic defrost, and either end ports (shown) or top ports for installation flexibility. Various sizes and cfm ranges are available per square footage and required air exchange rates. A trio of control options includes automatic recirculation and dehumidistat modes and continuous or intermittent fan operation. 800.227.7437. www.commercial.carrier.com.

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    RenewAire. HVI-certified EV Series ERVs achieve up to 76% heat recovery efficiency and serve general and spot ventilation needs. The units offer up to 315-cfm airflow rates to accommodate various conditions and requirements, feature MERV-8 filters, and consume less than 1 watt in standby mode. Cabinets are fully insulated with large internal cores for high efficiency and installation in conditioned or unconditioned spaces. Optional automatic proportional runtime control and push-button control are available. 800.627.4499. www.renewaire.com.
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    Honeywell. HVI-certified HRVs and ERVs (pictured) recover up to 80% of heating/cooling energy from exhaust air using about the same amount of energy as a 100-watt light bulb, says the company. Five-speed control, including frost control, enables optimum occupant indoor comfort; ERVs also regulate humidity to reduce indoor moisture problems. An optional adjusting dehumidistat and fan timer controls are available. 800.328.5111. www.forwardthinking.honeywell.com.
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    Panasonic. The WhisperComfort spot ERV is the first ceiling-inserted energy-recovery ventilator in the U.S., says the maker. Designed to address moisture-generating areas, the affordable unit enables builders and homeowners to scale their ventilation options while still meeting ASHRAE 62.2 standards. A low-rate, continuous-balance air flow powered by an enclosed AC motor vents and replaces VOCs and other indoor air pollutants with fresh air; a capillary core transfers heat and moisture to the supply air. A frost-prevention mode automatically activates at 32 degrees F (outdoor temperature) to prevent core freezing. 800.405.0652. www2.panasonic.com.
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    UltimateAir. The HVI-certified RecoupAerator ERV offers up to 200 cfm and 95% heat-recovery efficiency. The unit features a proprietary control for optimum energy efficiency (as low as 40 watts at 70 cfm) and a dehumidistat to monitor and balance humidity levels automatically and without desiccants. It can be mounted vertically or horizontally and connects to 6-inch galvanized or flex ducts. The unit features a 20-gauge-steel insulated casing with powder-coated finish and optional CO2 monitoring, MERV-12 filtration, and high-efficiency defrost. 800.535.3448. www.ultimateair.com.

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    Rheem. The HEPA 3.0 HRV is HVI-certified up to 75% of heat recovery and offers airflow rates up to 270 cfm. It serves up to 3,000 square feet per unit and features removable and washable metal-framed air filters, a smart defrost system to prevent freeze-ups, and 6-inch round inlets and outlets for easy duct connections. The 20-gauge, pre-painted steel with corrosion-resistant finish and sturdy damper design address adverse weather conditions. A standard HEPA filter captures 99.97% of all particles as small as 0.3 micron to enhance indoor air quality benefits. 334.260.1500. www.rheem.com.

  • Goodman AC

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    Frank White

    Goodman. The HVI-certified HRV series offers up to 92% heat recovery, according to the manufacturer, with cfm rates from 123 to 247 to accommodate various residential conditions and requirements. The units feature a 22/24-gauge galvanized steel cabinet that is fully insulated with 1-inch high-density polystyrene foam to help prevent condensation; other features include washable, electrostatic panel-type air filters and factory-balanced EBM motors with permanently lubricated sealed motor bearings. The aluminum core is configured for efficient cross-flow ventilation and to withstand extreme temperatures. An optional dehumidistat and air-quality sensor are available. 877.254.4729. www.goodmanmfg.com.
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    Fantech. The HVI-certified VHR 1404 heat-recovery ventilator is rated to recover and exchange 62% of exhaust air heat. The unit is equipped with two factory-balanced EBM motors with permanently lubricated sealed bearings for durability and low maintenance. An aluminum heat-recovery core is configured for efficient cross-flow ventilation; washable electrostatic panel-type air filters enable easy care. A preset defrost sequence automatically activates to protect the unit in extreme cold temperatures while maintaining fresh air intake and heat exchange. 800.747.1762. www.fantech.net.

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    Venmar Ventilation. The HVI-certified EKO 1.5 heat-recovery ventilator recovers and exchanges up to 80% of heated or cooled air. Two high-performance ECM motors consume 13.5 watts each at low speed and operate at 2.53 cfm per watt, making the units among the most energy efficient available. Four speed settings adjust to changing needs, especially when automatically controlled by a programmable touchpad (included). A defrosting system mitigates ice buildup on the recovery module. The unit’s compact size enables more installation options. 800.567.3855. www.venmar.ca.

Starting in 2011, all new homes built to comply with the federal Energy Star Qualified Homes standard—perhaps 200,000 units if the NAHB’s forecast for that year holds true—will be required to provide an adequate amount of controlled, fresh-air ventilation as part of a comprehensive energy conservation and indoor air quality goal.

Already, the ANSI National Green Building Standard (NGBS) and LEED for Homes require builders to meet the airflow (cfm) per square foot ventilation standards established in ASHRAE 62.2-2007 for residential applications, the same thresholds that Energy Star will apply.

All three programs allow multiple options for compliance and, in the case of the ANSI and LEED for Homes rating systems, award additional points toward certification for upgraded solutions.

Of those options and upgrades, an increasingly likely choice for builders is mechanical ventilation: whole-house heat-recovery ventilators (HRVs) or energy-recovery ventilators (ERVs) integrated into forced-air HVAC setups.

According to the “2008 NAHB Construction Technology Survey” of 2,700 builders nationwide, 56% already report using mechanical means to bring a controlled amount of fresh air into the home (and about half of those extensively), while another 12% are considering it. Meanwhile, the most recent “Annual Builder Practices Survey” by the NAHB Research Center found that HRV use among builders increased from 2.7% of all new single-family units in 2002 to 3.6%—or about 23,000 homes—in 2008.

Those aren’t earth-shattering numbers—yet. But the combination of tougher (and greener) building standards and codes that will require whole-house ventilation in new homes; concern and market demand for healthier indoor air; and the improved performance, reliability, and ease-of-maintenance of ventilation equipment positions HRVs and ERVs to work into the spec sheets of an increasing number of homes.

Consider the experience of Asheville, N.C., HVAC contractor Duane Gentry: During the last three years, he says, demand for ERVs has jumped from about 1% of his HVAC system installations to nearly 70%. That spike in demand, he says, is driven by consumers who are increasingly savvy about green building and by architects and builders who are trying to satisfy clients and qualify the energy efficiency and health of their projects. “We’re putting them in virtually every custom home project we have,” and a growing number of tract homes, says the owner of Gentry Heating and Cooling. “With new state energy codes [reducing air infiltration], it won’t be long before they’re mandated for all homes.”

How They Work

Simply, HRVs and ERVs provide a balanced, controlled, and measured amount of fresh air into the house to cycle out pollutants, while also capturing and exchanging the heat—or sensible energy—from the exhausted indoor airflow with the incoming air. This exchange preheats incoming air in the winter, or “pre-cools” it (if to a lesser extent) in the summer, reducing the energy demand on the home’s primary heating and cooling equipment.

Because furnaces, heat pumps, and air conditioners don’t have to work as hard or as long with an HRV or ERV supplementing them, they also might perform longer at optimum levels and achieve better investment values.

The equipment design of an HRV is fairly simple: It is typically comprised of two fans that push a balanced amount of incoming and outgoing air, respectively, through fixed filters (some with HEPA technology to capture most airborne pollutants) positioned to effectively facilitate an exchange of heat between the two flows. ERVs follow the same general design and concept but with an additional, separate chamber to manage humidity levels in the air exchange.

To enable whole-house controlled ventilation and maintain optimum indoor air pressure, HRVs and ERVs are sized based on the square footage of the home and the unit’s cubic feet per minute (cfm) rating, a calculation that roughly equates to 0.05 cfm per square foot of conditioned space; a 2,000-square-foot house, then, would require a unit with at least 100-cfm ventilation capacity to achieve a rate of 0.35 air changes per hour, the industry-accepted ideal exchange rate for good ventilation.

To effect that performance, ERVs and HRVs must be connected to the home’s central forced-air heating and cooling system, achieve a balanced airflow, and have two connections to the outdoors—one to bring in fresh air, the other to exhaust stale indoor air.

The two exterior duct ports need to be separated 4 to 6 feet from each other to avoid cross-contamination, while the intake pipe also should be placed away from gas meters, vehicle parking areas, combustion appliance vents, and trash receptacles. Suppliers typically offer angled hoods to accommodate circumstances where ideal distances between pipes and potential contamination sources cannot be achieved.

Inside, the fresh, incoming—and now semi-conditioned—air can be delivered from the HRV/ERV by an independent duct to one or more locations in the house or, more simply, connected to the return vent in a typical forced-air system.

The effect of introducing preheated or precooled air into a room or rooms will not only freshen the indoor air but also reduce demand on the heating or cooling equipment to condition the incoming air.

In contrast to the incoming air through the home’s forced-air network, the removal of the stale exhaust air must be ducted independently, ideally from several rooms in the house, directly to and through the HRV or ERV. In the case of an ERV, ducts should at least vent air from rooms that generate moisture, such as the kitchen (though not directly from a range hood), baths, and laundry areas. “That’s the ideal setup because you can eliminate bath fans,” Gentry says, a tradeoff that helps tip the upfront cost and labor premium for an HRV/ERV into better balance.

According to the EPA, HRVs are most cost-effective in extreme climates (hot or cold) and where energy rates are high; in mild climates, the energy consumed by an HRV may exceed the amount it can save.

In hot, humid climates—specifically a swath from East Texas along the Gulf Coast states and up through the Carolina coastline—the predominant need is cooling the indoor air and often the removal of humidity. For those environments manufacturers and building scientists recommend ERVs for whole-house controlled ventilation.

ERVs look and work similarly to HRVs, but with the added ability to regulate humidity levels in the incoming air before too much of that moisture is introduced to a cooling condition. By removing excess humidity—also called latent energy—from the incoming air, an ERV helps mitigate the potential for condensation and related problems of mold and degradation inside the house.