How heat pump work on HVAC system ?
Thanks

Dear buffalotu

HVAC : acronym for "heating, ventilating, and air conditioning".
Heat pump : a kind or reversed aircon system that is withdrawing heat from somewhere.
Often a system in which pipes are placed deep inside the soil, and through which cold water is pushed, to allow it to warm up by the earth heat, after which it is drawn up again to pass it through a heat exchanger, which brings the warm water into the home. When combined with an air duct system the heat can be distributed throughout the entire house.
One can also use the system in summer time to cool the house.

Although the temperature difference can be small, the heat pump can make use of it, and produce heat or cold cheaper than a real heater or aircon would do.