Energy recovery ventilators (ERV) and heat recovery ventilators (HRV) are mechanical exchange units that help reduce heating costs by retaining existing heat and optimizing the interior moisture content of the air. Energy recovery ventilators consist of a heat exchanger and a ductwork-based or wall-mounted ventilation system. They use four types of heat exchanger cores: cross-flow plate cores, counter-flow plate cores, heat pipe cores, and rotary wheel cores. Heat recovery ventilators are similar to ERVs, but use an air-to-air heat exchanger to introduce fresh air from the outside. HRVs that regulate humidity remove moisture from damp air and add humidity to dry air. Most energy recovery ventilators (ERV) and heat recovery ventilators (HRV) are installed in a building’s attic or crawlspace. Separating the connections for intake and venting helps to prevent cross-contamination. With HRVs, the supply inlet should be located away from personnel or machinery.

Selecting energy recovery ventilators (ERV) and heat recovery ventilators (HRV) requires an analysis of motors and drives, electrical components, housing materials, and insulation. Voltage, phase, sizing and speed are important specifications for motors and drives. Belt-driven motors and energy-wheel motors are matched to the fan’s load and may feature integral overload protection. In some models, energy wheels are mounted on slide-on tracks and consist of multiple sections. For maximum latent energy transfer, a silica gel is sprayed onto a polymer wheel. Electrical components for energy recovery ventilators (ERV) and heat recovery ventilators (HRV) are wired to single-point connections and may include fuses, motor contactors, a control circuit, and timing strip. Housing materials such as galvanized stainless steel prevent corrosion. Most ERVs and HRVs are insulated with fiberglass that is attached via waterproof adhesives or mechanical fasteners. Optional features include washable filters, digital timers, and weather hoods with mesh screens.