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fourthindiana
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- There was 28 volts from R to Y. Why was there zero volts from C to Y?
The attached photograph contains a diagram that represents my understanding of how thermostats are wired internally. I recently did six experiments with the low voltage wires in the air handler of my heat pump. Here are the results:
Experiment 1# With the heat pump running in cool mode, R to Y was zero volts.
Experiment 2# With the heat pump running in cool mode, C to Y had 27 volts.
Experiment 3# With the heat pump running in cool mode, R to C had 27 volts.
Experiment 4# After the thermostat was satisfied, R to Y had 28 volts.
Experiment 5# After the thermostat was satisfied, C to Y had zero volts.
Experiment 6# After the thermostat was satisfied, R to C had 28 volts.
The contradiction I see here is between experiments #4 and #5. It might be the case that I see a contradiction because I am relying on a false premise of some sort. My understanding is that when the thermostat is satisfied, the switches are like the switches in the diagram in the attached photograph, with all the switches open. I know that when one reads voltage on each side of a wire across an open switch, one gets a voltage reading, not zero volts. I also know that when one reads voltage on each side of a wire across a closed switch, one gets zero volts because there is no potential difference between the two points. In experiment #4, the switch from R to Y was open. Therefore, I understand why there were 28 volts from R to Y. However, on experiment #5, C is receiving 24 volts from the transformer, and Y is not receiving any volts from the R side of the transformer. Therefore, on experiment #5, I would have expected there to be 24+ volts from C to Y since C is receiving 24 volts from transformer, and C is not connected to Y. On experiment #5, why was there zero voltage from C to Y?
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P.S. I think I should mention that I don't know for a fact that my thermostat is wired up like I depicted my thermostat in the diagram in the attached photograph. That might be a false premise that I am relying on. The diagram in the attached photograph is just my understanding of how my thermostat is wired up.
Experiment 1# With the heat pump running in cool mode, R to Y was zero volts.
Experiment 2# With the heat pump running in cool mode, C to Y had 27 volts.
Experiment 3# With the heat pump running in cool mode, R to C had 27 volts.
Experiment 4# After the thermostat was satisfied, R to Y had 28 volts.
Experiment 5# After the thermostat was satisfied, C to Y had zero volts.
Experiment 6# After the thermostat was satisfied, R to C had 28 volts.
The contradiction I see here is between experiments #4 and #5. It might be the case that I see a contradiction because I am relying on a false premise of some sort. My understanding is that when the thermostat is satisfied, the switches are like the switches in the diagram in the attached photograph, with all the switches open. I know that when one reads voltage on each side of a wire across an open switch, one gets a voltage reading, not zero volts. I also know that when one reads voltage on each side of a wire across a closed switch, one gets zero volts because there is no potential difference between the two points. In experiment #4, the switch from R to Y was open. Therefore, I understand why there were 28 volts from R to Y. However, on experiment #5, C is receiving 24 volts from the transformer, and Y is not receiving any volts from the R side of the transformer. Therefore, on experiment #5, I would have expected there to be 24+ volts from C to Y since C is receiving 24 volts from transformer, and C is not connected to Y. On experiment #5, why was there zero voltage from C to Y?
___________________________________________________________________________-
P.S. I think I should mention that I don't know for a fact that my thermostat is wired up like I depicted my thermostat in the diagram in the attached photograph. That might be a false premise that I am relying on. The diagram in the attached photograph is just my understanding of how my thermostat is wired up.
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