Hvac controller

An alternating current (AC) load switch circuit comprising:

• a first power input terminal configured to receive AC power from a transformer;
• a second power input terminal;
• a power output terminal configured to connect to an HVAC load;
• and
• processing circuitry configured to:
• receive a first indication when the HVAC load is connected to the power output terminal;
• receive a second indication when a voltage magnitude at the second power input terminal is above a threshold voltage;
• output a drive signal to a power converter circuit in response to receiving the first indication and the second indication.

A method comprising:

• receiving alternating current (AC) electrical power at a first power input terminal;
• receiving an electrical connection at a power output terminal;
• charging an electrical power storage device using power from a load when the load is connected to the power output terminal;
• determining a voltage level of the electrical power storage device in response to the load being connected to the power output terminal;
• and
• outputting a drive signal to a power converter circuit if the voltage level is above a threshold voltage.