New Furnace Minimum Efficiency Standard

90% AFUE furnaces set to become the Legal Minimum on May 1, 2013

 The DOE is implementing a regionalized system (vs. one rule for the entire country).  The minimum efficiency required in Illinois will be 90% AFUE.  This applies to both new construction and replacement equipment. This means that distributors are likely to start reducing their stock of 80% furnaces this winter so they are not stuck with inventory that is illegal to install. 

80% AFUE furnace with sheet metal flue pipe.

If you have a furnace that has a sheet metal flue pipe that vents into a chimney, you have a furnace that has an efficiency rating of 80% AFUE or less (the percentage of heat that makes it into the home vs. the amount wasted up the chimney). After May, you will not have the option of replacing it with a similar furnace that can be vented into a chimney or vertical metal flue. The minimum efficiency furnace available will be 90% AFUE which requires venting via 2" or 3" PVC piping directly through an outside wall or through the roof. 

There are many situations where this may not be practical such as finished basements where the furnace is not adjacent to an outside wall, or in condominiums that are not on the top floor of the building which may require running new PVC vent piping through neighbors' units above - between the furnace and the roof. 

There are also many codes and procedures for venting 90+ furnaces which may prohibit using the closest outside wall such as: minimum height off the ground, not venting within 4 feet of a window or electrical/gas meters, or venting beneath an outdoor deck, among others. There are also complications with having a water heater being the only appliance venting into an old unlined chimney. The chimney was originally sized for a lot of heat from inefficient furnaces and water heaters being dumped into them during winter. This allowed the flue gases to make it all the way out the top of the chimney. When the furnace is updated to a 90+ and no longer vented into the chimney, there will not be enough heat from the water heater flue gases to prevent them from condensing half way up the chimney causing damage to the brick and mortar, and creating potentially hazardous conditions.

Of course we always recommend replacing an old ineffeicent furnace with a 90% or higher AFUE model as the best long term option. But for a few more months you still have a choice.

 

Call Perri-Aire for fast, quality HVAC service in Chicago-land at 773-777-4888.