According to a price catalogue provided by WebHvac.com, Armstrong gas furnaces range in price from $1200 to $3600. Different gas furnace models also differ in price. Gas furnaces with higher British Thermal Units cost more. BTU is a unit of work equal to about 1055 joules.
There are three common types of Armstrong gas furnaces; modulating gas furnaces, two-stage gas furnaces and single-stage gas furnaces. The modulating furnaces have a variable-capacity gas valve that produces an exact amount of heat needed even indoor temperatures. This type is among the most expensive of Armstrong's gas furnaces. Varying fuel efficiencies also affects the pricing of Armstrong gas furnace units.