AFUE (annual fuel utilization efficiency) is the rating given to approximate the efficiency of residential furnaces. Like MPG, the higher the number the more efficient the furnace.

Most gas utilities offer rebates for purchasing furnaces which reach a minimum 92% AFUE and some offer even higher rebates if 94% or higher is attained. But, none of the gas utilities (that I am aware of) offer rebates for multi-stage or modulating gas combustion–WHY NOT ??

In Minnesota we must install furnaces sized to heat our homes to an outdoor temperature of -16 degrees. Logic tells us that if the furnace is sized for minus 16 degrees it can easily heat our home at 0 degrees or even freezing (32 degrees). Logic also tells us that it takes a larger furnace or more BTU’s (British Thermal Units) to heat our home in colder temperatures.

In an average Minnesota winter, we have approx 8000 heating hours of which less than 10 hours is at -16 degrees ( the temperature we must size the furnace to).
It other words, the other 7990 hours the furnace is working to heat our home IT IS OVERSIZED.

Oversized furnaces lead to cold spots , uncomfortable rooms and short cycling run time. There is a cure for this built into many of today’s furnaces. Multi-stage and modulating gas valves combined with ECM blower motors will more closely match the needs of the home as outdoor temperatures change.

Which leads me to my point, there’s more than just efficiency. Our gas utilities are not offering enhanced rebates for the furnaces which contain these energy saving features. I am truly dumbfounded that the utilities do not recognize the benefits of these features by offering a much higher rebate for these furnaces.

Please do your homework when considering a new furnace and don’t miss this opportunity to choose a furnace that matches the heat loss of your home, not one which is OVERSIZED 99% of the time.