A voltage monitor is a diagnostic or protective device that ensures the power entering your HVAC system is within the safe operating range (usually 187V to 253V for a 230V system). If the voltage drops too low (brownout) or spikes too high, the monitor will automatically disconnect the unit to prevent motor burnouts. This is a critical accessory for our 55000 BTU and other large-capacity systems that pull significant current. Protecting your heat pump condensers from unstable power is one of the best ways to ensure a 15-20 year lifespan. You can find these and other electrical parts in our specialty accessories store. It is a must-have for rural areas with inconsistent power grids.