What wires do you need to jump to check the heating circuit?

To check the heating circuit in an HVAC system, you need to jump the R wire and the W wire. The R wire typically represents the 24V power source from the transformer, while the W wire is the control wire that activates the heating system.

When these two wires are connected, it simulates a command to the thermostat that tells the heating system to turn on. This is commonly done for testing purposes, ensuring the heating circuit operates correctly. If the heating system activates when these wires are jumped, it indicates that the circuit is functioning, and the issue may lie elsewhere, such as with the thermostat or the system itself.

The other combinations of wires would activate different functions in the system. For example, jumping R and Y would engage cooling, R and G would turn on the fan, and R and B typically relate to heat pump systems. Therefore, these combinations would not effectively check the heating function specifically.