What is a Heat Recovery System?

A heat recovery system is used to improve the energy efficiency of a residential or commercial building. While standard heating systems allow heat to escape as wastewater or exhaust air, a facility equipped with a heat recovery system is able to capture and reuse this heat energy. There are two basic types of recovery systems, including wastewater and ventilation systems. Some buildings are equipped with one type of heat recovery system, while others have a combination unit that serves a dual purpose.

A drain heat recovery system captures heat from wastewater as it is flushed down the drain. In many cases, the wastewater passes through a copper coil filled with refrigerant. The refrigerant removes the heat from the water, then transports it to a fresh water storage tank. This heating energy is used to warm the water in the tank, which is then distributed throughout the home to showers, sinks and other fixtures.

Homeowners can also look for tank-free water heat recovery systems. The wastewater exits through the drain pipe normally, and does not pass through a refrigerant coil. Instead, the incoming fresh water supply piping is coiled around the drain pipe. As the fresh water travels around the drain pipe, heating energy from the wastewater is transferred to the fresh water supply.

Heat recovery systems are also used with home ventilation systems. The home's heating unit produces warm air, which is distributed throughout the home through ductwork. A second set of ductwork collects stale air from various rooms and brings this air back to the unit so it can be expelled from the home. A heat recovery system can be used to remove some or all of the heat from the air first.

In a heat recovery ventilation system, as the exhaust air travels back to the furnace, it passes through a copper heat exchange coil. The coil collects heat from the air and transfers it through the unit to the fresh air supply. This recovered heating energy is then used to warm the fresh air before it is distributed through the home. The exhaust air and the fresh air supply never meet, so there is no risk of stale air being transported back into the duct system.

A heat recovery system offers many benefits to both residential and commercial users. It can reduce energy consumption, which often results in lower utility costs. Because less energy is needed for heating, these systems can also reduce the user's impact on the environment. Heat recovery systems allow users to achieve a balance between energy efficiency and healthy indoor air quality, and also keep valuable heat energy from going down the drain.