Assertion: low voltage wiring | /r/Desires | four wires
Facets:
value: for heat / cool / fan
type: PURPOSE
Source sentences:
text: In the most basic system, this functionality is provided by use of a fan center relay, and the low voltage wiring to the thermostat now will require a minimum of three wires (for heat only units) and four wires (for heat / cool / fan) for control.