AFUE is the rated efficiency of a combustion furnace. For example, a 95% AFUE model loses 5% of its produced heat up the chimney. In other words, $1 of fuel combusted in an 80% AFUE model loses $0.20 before it even enters the ducts.

Heat pumps, air conditioners, and modern furnaces produce condensation and the removal of this collected water is always considered in system design. 

The “cold air return” is the intake side (sucking side) of a duct system. This duct pulls air from the home and feeds it to the furnace to be reheated for distribution. Leaks in the return air duct are very important to seal as they allow material to be pulled in from wherever they lead (attics, crawlspaces, etc.). Unducted wall cavities are not ac [..]

This is an efficiency rating system that compares the output of heat to the consumption of electricity. An electric baseboard or electric furnace (aka resistance heat source) has a COP of 1.0, which means that for every unit of electricity that goes in, you get one unit of heat energy out. A heat pump may have a COP of 3.0- for every unit of electr [..]

Filters located on either the furnace or grille end of the intake duct protect the furnace components from the build-up of airborne particles. More advanced filtration systems can be effective at cleaning the air in a home, but only if the duct and house leakage has been addressed. Filters are rated on the “MERV” scale based on how small of particl [..]

According to extensive nationwide studies, duct leakage is a leading cause of wasted energy, poor indoor air quality, excessive dust, and comfort complaints. A study by the U.S. Department of Energy found that the typical duct system loses between 25% and 40% of its paid-for heat! Leaks are repaired with either hand applied material or a more compr [..]

Proper duct sizing is of absolute importance in effectively delivering conditioned air to the home. Improper duct sizing can lower the efficiency of the system, limit distribution (affecting comfort), and cause unnecessary ware on equipment.

Think “toaster”. Baseboard heaters, wall heaters and electric furnaces are all forms of electric resistance heat technology and produce heat by passing electricity through a material that causes “resistance,” heats up and then radiates that heat either into an air stream or directly into a room. This is a very inefficient form of heating by modern [..]

There are two types of fan motors in the world of furnaces:

Ductless Heat Pumps are the world’s most popular heating system. For most standard application, they are the most efficient and cost effective to install. For this reason, utility companies offer significant incentives to upgrade. This is a zonal heating system that operates on a refrigerant technology (see “Heat Pump” below). They do not utilize a [..]