What is a Heat Recovery Ventilation System?

One of the most frequent concerns with heating, ventilation, and air conditioning (HVAC) systems is how to balance energy efficiency with proper ventilation. As the focus on green building has increased over the years, builders have responded by constructing homes more tightly. Tighter homes allow less air to leak through exterior walls, resulting in improved energy efficiency.

As housing construction has gotten tighter, however, there have been fewer natural paths left in the buildings to allow fresh air to enter the home. This lack of fresh air can result in poor indoor air quality, along with mold growth and other moisture-related problems. Poor ventilation can also make a building feel stuffy, and may lead to unpleasant odors inside the home.

Mechanical ventilation can be used to address this issue. With mechanical ventilation systems, stale air is removed from the house through an exhaust system, while fresh air is drawn is through fans or louvers. The more fresh air that is brought in, the more stale air must exit to maintain equilibrium pressure levels between indoors and out. As air leaves the home however, it takes expensive heat with it.

To enjoy the benefits of both conditioned air and adequate ventilation, homeowners can use a heat recovery ventilation system. This device is used in conjunction with the HVAC system to remove valuable heat from exhaust air before it exits the home. The heat recovery ventilation system collects this heat, then distributes it into fresh air as it enters the home. This means that less heat is wasted, and energy efficiency levels are improved.

A heat recovery ventilation system can be installed in the basement or on the rooftop to work alongside existing HVAC equipment. It is connected to the supply and return ducts in the home, which enter the heat recovery unit through separate pathways. One fan in the recovery unit draws stale air in from the home. Another fan within the unit draws in fresh air from outside. As the exhaust air passes through the core of the unit, heat is collected inside of this core before the air is exhausted to outside.

As the heat recovery ventilation system draws fresh air in, the air passes through the core of the unit. As it passes, it collects the heat left behind from the exhaust air. The heat is then transferred to the supply air and distributed through the home.

This type of heat recovery ventilation system can have the opposite effect in the summer, while still maintaining energy efficiency in the home. In hot weather, fresh intake air passes through the unit's core, where the heat is collected. As exhaust air from the home passes through the unit, it collects the heat and transfers it to the outdoors. This prevents hot air from outdoors from mixing with cool air inside the home.