Single Stage vs. Two Stage

Throughout SE Michigan, homeowners are requesting now more than ever, that FLAME Furnace install a two-stage furnace over a standard single stage. The two-stage furnace will be a larger investment up front, but the longer you live in your home, the more you will be able to take advantage of the comfort and savings. What is a two stage furnace?  A two-stage furnace has two heat settings, a high-heat and a low-heat setting.  When the outdoor temperature begins to drop (especially during fall and spring), but hasn’t yet reached the frigid Michigan winter, your furnace comes on to take the chill out of the air.  This is an ideal time for the low-heat setting which will deliver an efficient soft heat to keep the house comfortable.  Then when the inevitable bone-chilling temperatures hit, your furnace will then come on in the high-heat setting to keep you warm even on the coldest days.

Those cool-but-not-cold transition periods are when the two stage furnaces show the most of their value for several reasons.  The first reason is that when a single stage furnace comes on, it will blast single stage high-heat into your home.  This will quickly satisfy your thermostat and shut off the furnace.  The furnace will then short-cycle, or turn off and on too many times during a given period.  This causes uneven heat distribution and puts undue wear on the equipment.  It also reduces your furnace’s efficiency similar to a car driving in stop and go traffic instead of highway driving.  The unfortunate result is a higher gas bill.  A low-heat setting would be perfect for this scenario because it can put in a soft, even heat for a longer period of time.  This gives each room more even heating, and both reduces gas bills and prolongs your furnace life by operating in the “highway driving mode“ instead of “stop and go mode.“ The benefits of the two-stage furnace continue when you have a humidifier, and arise because your humidifier only humidifies the air when the furnace is on.  Since a low-heat setting allows the furnace to provide longer, more even periods of heating, it also allows longer periods of whole-house humidification.  This is contrary to the high-heat setting where humidification only occurs during the short blasts of heat before the thermostat is satisfied.  The better humidification with the two-stage furnace will help keep you more comfortable, reduce the negative effects caused by dry air, and will also reduce your energy bill (see the article on humidification to learn how proper whole-house humidification can reduce your energy bills).