So as Summer approaches, you might be considering the plunge to either upgrade your HVAC or add on some cooling.  In an effort to make the buying process easier on you, we want to explain how the differing systems work.


This only applies to the heating system.  It is a differing speed of the burner, another way to say that, a differing amount of gas used.  It continually runs but the output varies.


Heating: It can be described as the differing amount of electricity used, or the differing speed of the blower/fan.  Controls the amount of airflow which helps control temperature and humidity.

Cooling: The compressor works are variable levels, which changes the amount of output.


For both heating and cooling, it operates at different levels of capacity.  It creates a more even temperature distribution because it doesn’t shut off before a room gets a chance to warm up or cool down.  It also doesn’t overheat or overcool smaller rooms because it doesn’t operate at full capacity.  It runs at a lower capacity for a longer amount of time.

Single Stage

Simply put, it only has two options, on or off.  It’ll run at full capacity until the indoor thermostat temperature is met and then it will shut off.

This isn’t an in depth explanation of how they work, but it will give you an idea of what you might want.

Generally speaking, if ranked from most efficient to least efficient, it would go Variable –> 2-Stage –> Single Stage.  It would be a little different for the heating system, variable and modulating are very similar in efficiency levels, it only depends on the type of power you favor.  Say you have solar panels, for you, variable speed might be a better option because the solar could supplement the electricity use.

The best thing to do is to talk to an HVAC expert about it.  They can help you determine the best design for your home!  If you’re interested, you can give us a call at 408-376-0406 or visit us online at  For more HVAC and energy tips, follow us on Twitter and like our page on Facebook.