Arkansas HVACR NewsMagazine March 2022

HVACR NewsMagazine March 2022

Tech News

Loads

In simple terms, loads are the parts of the circuit that actually do something. They take the power and transform it into some other kind of energy. (For example, a lightbulb is a load that takes electrical energy and converts it to heat and light energy.) Unlike switches, loads consume power when they operate. Examples would be the reversing valve solenoid and the contactor coil. On schematics, a load may look like a coil or a line that goes up and down between two circles (as you'll see in the contactor coil example below). In the case of the contactor coil, the contacts up top are the switches, and they are normally open. Because they are normally open, there is no path for electricity to reach the equipment, meaning that the compressor and condenser fan can't turn on. When a call for Y sends 24v to the contractor coil and energizes it, the electromagnet pulls the contact in, creating a path for electricity to go out to the outdoor components.

Thermostat wiring

The cool thing about thermostat wires is that they tend to be mostly color-coded. That is, G matches up with green, O matches with orange, etc. However, each wire has a specific function when it comes to low- voltage wiring. Here are the functions we typically use on a thermostat for a heat pump (colors are in parentheses):

• R H : constant 24v power for heating mode (red)

C: common (blue)

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Y1: contactor (yellow)

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G: blower (green)

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