Which device is a heat recovery type?

Which device is a heat recovery type?

• A. Enthalpy wheels
• B. Air filtration unit
• C. Solar panel
• D. Heat pipe or runaround coil

Answer: (D)

Heat recovery means moving energy from the exhaust air to the incoming fresh air so you don’t pay to heat the space twice. A heat pipe or runaround coil accomplishes this with a dedicated energy-transfer path between air streams. A heat pipe uses a sealed container with a working fluid. On the exhaust side, the fluid absorbs heat and boils; the vapor travels to the supply side, where it condenses and releases heat into the incoming air, returning to the hot side to repeat the cycle. A runaround coil uses a closed liquid loop that siphons heat from the exhaust coil to a separate coil in the supply duct, transferring warmth without mixing the air streams. Both are classic ways to recover heat. An air filtration unit doesn’t transfer heat; it only cleans air. A solar panel collects solar energy rather than transferring heat between air streams. An enthalpy wheel does transfer heat (and moisture) between streams, but the option highlighted here is the straightforward energy-transfer method via a heat pipe or runaround coil, which clearly fits the heat recovery concept.

Heat recovery means moving energy from the exhaust air to the incoming fresh air so you don’t pay to heat the space twice. A heat pipe or runaround coil accomplishes this with a dedicated energy-transfer path between air streams.

A heat pipe uses a sealed container with a working fluid. On the exhaust side, the fluid absorbs heat and boils; the vapor travels to the supply side, where it condenses and releases heat into the incoming air, returning to the hot side to repeat the cycle. A runaround coil uses a closed liquid loop that siphons heat from the exhaust coil to a separate coil in the supply duct, transferring warmth without mixing the air streams. Both are classic ways to recover heat.

An air filtration unit doesn’t transfer heat; it only cleans air. A solar panel collects solar energy rather than transferring heat between air streams. An enthalpy wheel does transfer heat (and moisture) between streams, but the option highlighted here is the straightforward energy-transfer method via a heat pipe or runaround coil, which clearly fits the heat recovery concept.