The air conditioner/heat pump has a compressor with two degrees of operation: high for hot summer days and low for cooler days. While the low setting is adequate to meet household-cooling demands 80% of the time, a two-stage unit runs for longer periods and produces more balanced temperatures.

The furnace has two stages of heat output: high for cold winter days and low for milder days. Since the low setting is adequate to meet household-cooling demands 80% of the time, a two-stage unit runs for extended periods and delivers more uniform heat distribution.

A thermostatic expansion valve ( TXV) is precision device used to meter the flow of liquid refrigerant entering the evaporator at a rate that matches the amount of refrigerant being boiled off in the evaporator. Also called a thermal expansion valve.

A series of sensors and relays that monitor and control the functions of a heating and cooling system by turning the device on or off when a specified temperature is reached.

The combination of an outdoor unit (air conditioner or heat pump) with an indoor unit (furnace or air handler). Split systems must be paired for optimal efficiency. This is the most common type of system installed in a home.

All aluminum outdoor coil that features the patented Spine Fin™ design. Spine Fin™ consists of thousands of tiny spines bonded to continuous aluminum refrigerant tubing. The tiny spines create a greater surface area, helping it to transfer more heat from your home, more efficiently. It provides greater heat exchanging capabilities (meaning higher efficiencies) and is…

A unit of measurement used for determining the cooling capacity of a system. One ton of cooling is based on the amount of heat needed to melt one ton (2000 lbs.) of ice in a 24 hour period. One ton of cooling is equal to 12,000 BTU/hr.

Any device that responds to a change in the conditions being measured, permitting the condition to be controlled.

That heat which, when added to or taken away from a substance, causes a change in temperature.

A refrigerating system that can be moved without disconnecting any refrigerant lines; also know as a package unit.