Arkansas HVACR NewsMagazine March 2022

HVACR NewsMagazine March 2022

Tech News

• O/B: reversing valve in cooling mode (usually orange; dark blue on Ruud or Rheem systems) • W2: auxiliary heat, backup heat, or heat strips (white) • ACC+: dehumidification (black) In this case at least

and purposes, the transformer is where our 24v power comes from. A transformer is designed to take 230v from the power company and drop it to 24v. So, 230v comes in on the primary, and 24v goes out the secondary. Although power transfers from the primary to the secondary, the two don't actually touch; they interact electromagnetically. After 24v exits the secondary, it goes to the integrated circuit board at SEC1 and SEC2. When 24v power leaves the transformer and goes to the integrated circuit board, it goes through a 5-amp fuse and powers the R terminal on the thermostat. We can configure the float switch to break R or Y when it trips. When the float switch opens the circuit by breaking R, 24v power shuts off to the thermostat AND the condenser defrost control because the wires to the thermostat and defrost control are kept together under the same wire nut. The defrost board needs constant 24v power to run its timer and logic. That is where the trail begins... Breaking circuits on R and Y

The electrical circuit

Now that we know a little bit about the low-voltage wiring of a heat pump, let's go into the electrical circuits. We will explain how transformers work, how float and pressure switches can break power on certain terminals, and how the defrost board and thermostat are connected. The source of all power: the transformer Maybe that heading isn't TOTALLY accurate. After all, solar panels and fossil fuels exist. But for our intents