A device that transfers heat from a colder area to a hotter area by using mechanical energy, as in a refrigerator
A heat pump is a machine or device that moves heat from one location (the 'source') at a lower temperature to another location (the 'sink' or 'heat sink') at a higher temperature using mechanical work or a high-temperature heat source.
(Heat pumps) Heat pumps use heat from either the ground or the outside air to heat a building. Ground- and Air- source heat pumps are not completely ‘renewable’ as they require electricity to drive their pumps or compressors.
apparatus that extracts heat from a liquid that is at a higher temperature than its surroundings; can be used to transfer heat from a reservoir outside in order to heat a building
Assistance or advice given to customers during and after the sale of goods
The action of helping or doing work for someone
an act of help or assistance; "he did them a service"
An act of assistance
work done by one person or group that benefits another; "budget separately for goods and services"
be used by; as of a utility; "The sewage plant served the neighboring communities"; "The garage served to shelter his horses"