The maximum voltage for thermostats is 22 volts.

• A. False
• B. 12 volts
• C. True
• D. 120 volts

Answer: (C)

Thermostats are designed to be low-voltage control devices in HVAC systems. They typically connect to a transformer that supplies around 24 volts AC, which is considered the control voltage for triggering furnaces, air conditioners, and other equipment. Because of variations in transformer output, wiring losses, and the need to keep components within safe limits, the practical maximum voltage that thermostat circuitry is designed to withstand is about 22 volts. This means the statement that the maximum voltage for thermostats is 22 volts reflects the common design ceiling for thermostat control circuits, even though the nominal supply is often 24 volts.

So the statement is true. Higher voltages like 120 volts would require different equipment and safety protections, while 12 volts is not the standard maximum for these control circuits.