Which terminal on the thermostat sub-base is used to power the heating system in a dual transformer system?

In a dual transformer heating system, the terminal on the thermostat sub-base that powers the heating system is typically denoted by "W". However, in the context of a dual transformer setup, the "RH" terminal is specifically used to connect to the heating transformer. This is where the heating power source comes from, making it essential for the operation of the heating system.

The "RH" terminal provides a dedicated power supply for heating. While "R" often supplies power for cooling in single transformer systems, in dual transformer systems "RH" is specifically designated for heating functions. This distinction is crucial for ensuring that the heating system operates correctly without interference from the cooling circuit, which would be powered by the "Y" terminal.

Understanding this configuration is important in HVAC systems, as it allows for proper installation and troubleshooting. Each terminal serves a specific role, ensuring that the heating and cooling systems operate efficiently and independently when needed. In this case, the "RH" terminal is the correct choice for powering the heating system in a dual transformer setup.