How to zone a forced air furnace and air conditioner ask this old house duration. Attach the low voltage side of the transformer to the.
This complete 24 volt thermostat wiring guide covers all thermostat wiring issues from the simple to the complex.
24v thermostat wiring diagram. One supply wire will be the black voltage wire attached to the fuse or circuit breaker. R the r terminal is the power. This information is designed to help you understand the function of the thermostat to assist you when installing a new one or replacing or up grading an old one.
The other power supply wire will be white this is the electrical systems neutral or common. We do not cover 110 240 volt thermostat wiring and millivolt thermostat wiring issues. It is a red wire and comes from the transformer usually located in the air handler for split systems but you may find the transformer in the condensing unit.
Nest thermostat installation wiring photo guide opening the box containing a nest learning thermostat you ll find the thermostat itself as well as additional tools and parts that we ll list below. Thermostat wiring and wire color chart thermostat wiring colors code. Modern thermostats with wi fi and backlit display by contrast need a steady supply of juice the c wire or common wire enables the continuous flow of 24 vac power to the thermo.
In this article i am going to explain the function and wiring of the most common home climate control thermostats. We address them in order from most common to least common. Look for and read the installation instructions provided by nest as you ll find those 12 steps listed illustrated and explained below simple to follow.
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In fact the wiring of a thermostat is quite simple circuitry the confusion arises principally because. Color of wire and termination. The 24vac supply goes to the thermostat and one side of the relay coil.
Basic thermostat types. Thermostatic wiring principles by bob scaringe ph d p e. Attach the two black wires from the transformer to the 120 vac power supply wires.
Back in the olden days thermostats were simple on off devices that didn t need their own continuous power supply. Many technicians have great difficulty understanding how to properly wire a thermostat or how to replace a thermostat with a different thermostat. You need a 24 vac transformer to power the thermostat and a 24vac coil 120vac or more contact 1amp or more contact relay.