How A Furnace Works

A Gas Furnace (3) produces heat by igniting natural gas in its burner section. A blower fan in the furnace then blows indoor air across the heat exchanger. This heats the air which is then blown through the duct system to the rooms where heat is required.

Efficiency Ratings

Heating and cooling unit efficiency is rated by 3 primary methods, SEER, AFUE and HSPF. These allow you to compare the different products of different manufacturers.

(All the following assumes no energy loss due to duct or other types of leakage)

SEER

Stands for Seasonal Energy Efficiency Rating and is used to rate the efficiency of an air conditioner. The higher the SEER, the more efficient the air conditioner. For instance going from a 7 SEER unit to a 14 SEER unit would reduce your cooling bill by 50%

AFUE

Stands for Annual Fuel Utilization Efficiency. It is used in gas furnaces and is a measure of the efficiency of the gas furnace in converting fuel to energy. The higher the rating, the more efficient. As a rule of thumb, an 80 % efficient furnace, converts 80% of the natural gas to heat with the remaining 20% disposed of as combustion by products.

HSPF

Stands for Heating Seasonal Performance Factor. It is used as a measure of efficiency for heat pumps. The higher the number, the more efficient the heat pump.

HEATING AND COOLING - COST COMPARISON
2,500 SQUARE FT HOME - ATLANTA WEATHER

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