The most popular choice for home heating is a furnace. Furnaces can be heated by oil, propane or natural gas, with natural gas being the most common.
Natural gas furnaces come in 3 types – Standard efficiency, Mid-efficiency and High-efficiency. The efficiency of a furnace depends on it Annual Fuel Utilization Efficiency (AFUE) – the ratio of heat output to the total energy consumed by the furnace.
A Standard-efficiency furnace has an AFUE of 50-79% and is common in most homes today. However, they are no longer available for purchase. These units use a standing pilot light, a single stage heat exchanger and air from indoors for combustions.
A Mid-efficiency furnace has an AFUE of 80-85%. Like the Standard-efficiency furnace, these too use a single stage heat exchanger. In addition, they feature electronic ignition, a power controlled vent fan and indoor air for combustion. A Mid-efficiency furnace reduces the indoor air lost up the chimney.
A High-efficiency furnace is the smartest choice when shopping for a new furnace. They have an AFUE of 90-97% and have an additional heat exchanger that recovers an additional 10-17% of the heat produced by the burning gas. Cooler exhaust gases are vented through a wall, as opposed to up a chimney. The presence of an electrically ignited burner rids the need for a pilot light.
High-efficiency furnaces can save upwards of 40% when compared to a standard-efficiency model, depending on the combustion and heat exchange design. Greenhouse gases released in to environment are also reduced. An additional 20-30% reduction in electricity use is possible if the unit has a variable speed brushless Direct Current Electronically Commutated Motor (DC ECM) furnace blower motor, as opposed to the standard AC induction motor.
ENERGY STAR qualified oil and gas furnaces have an AFUE of 83-90% or more, depending on the fuel source. These models are up to 15% more efficient than standard models. For optimal performance and savings, choose an ENERGY STAR qualified furnace.
The temperature your furnace operates at is controlled by a thermostat. For optimal thermostat settings and other heating ideas, please see the tips below.