What is the difference between a single-stage and multi-stage thermostat?

A single-stage thermostat is designed to control heating and cooling systems that have only one stage of operation. This means that the thermostat can turn the system on and off, but it cannot adjust the system's output to meet changing temperature requirements. Single-stage thermostats are most commonly used in older heating and cooling systems, such as those with furnaces and air conditioners.

In contrast, a multi-stage thermostat is designed to control heating and cooling systems that have multiple stages of operation. These systems can adjust their output based on the temperature requirements of the space they are heating or cooling. Multi-stage thermostats can switch between different heating or cooling stages based on the desired temperature, which can result in more precise temperature control and energy savings.

Multi-stage thermostats are commonly used in more advanced HVAC systems, such as those with heat pumps, variable speed fans, or zoned heating and cooling. They can be more expensive than single-stage thermostats, but they can also offer greater comfort and energy efficiency by providing more precise temperature control.