What Is The Difference Between A Single-Stage And Multi-Stage Air Conditioner or Furnace?

by | Jul 11, 2017 | HVAC Blog

Single-Stage Air Conditioner or Furnaces

Imagine standing on a treadmill. You turn it on and instead of ramping up you go from standing still to a full sprint- immediately! It’s a rough way to work out. “Single-stage” means “off” is at standstill and “on” is running at full speed. These air conditioners and/or furnaces only have one phase of cooling or heat output– high or maximum. While single stage units may make sense in mild climates or in tight budget or rental property situations, two-stage HVAC units function much more efficiently.

Two-Stage Cooling and Heating

In most climates, instead of running at max speed 100% all the time, with a two-stage HVAC unit, the first stage runs at only about 65% of maximum output most of the time. This saves you energy and a big chunk of money! When the outside temperature becomes extremely hot or cold, this first-stage may become inadequate to meet the demand. Automatically, stage two engages to boost output for additional cooling or heat. Two-stage air conditioning packages run quieter, are more comfortable, and save energy because they don’t blow full-blast continually.

Modulating Air Conditioning

In contrast to both single and two-stage systems, the fan motor in modulating units blows at different speeds to control the amount of conditioned air dispersed throughout the home as it is needed. Think back to working out on a treadmill– walking on a level surface, requires less energy– walking up an incline requires substantially more effort– and running up a hill demands maximum effort. You might notice the blower motor of a modulating unit continually circulates air throughout the home even when the furnace is not “on,” thereby eliminating hot and cold spots. This results in less energy consumption, a much more comfortable environment, and noticeably lower utility bills.

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