Heat exchanger - a device used to transfer (exchange) heat or thermal energy. Usually heat exchanger is an area, box or coil where heat flows from the warmer to the colder fluid or surface. The major part of the furnace that transfers heat into your home.
Heat exchangers are either given a hot fluid to provide heating or a cold fluid to provide cooling.
- A hot/cold fluid can be either a liquid or a gas
- Heat always flows from hot to cold
- There must be a temperature difference for heat to flow
Thermal energy is transferred via three methods.