The two main types of gas furnaces in the home are theconventional furnaceand the newer high-efficiencycondensing furnace.
Because the exhaust gases are still very hot, all of that heat is wasted.
But high-efficiency furnaces often incorporate additional technology.
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These filters need to be changed regularly to make it work effectively.
Different classes of filters are available, depending on your needs.
The latter is used with two-stage, or modulating, furnaces and is more energy-efficient than a standard motor.
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Blower Compartment
Blower compartments on high-efficiency furnaces are usually insulated to retain heat.
Conventional furnaces usually are not insulated.
Electronic Ignition
Condensing furnaces always useelectronic ignition systemsfor maximum efficiency and reliability.
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Older standard furnaces may use a standing pilot system, although newer ones may have electronic systems.
The combustion air intake usually is piped from the exterior of the home to the furnace.
This means the furnace does not take air already heated by the furnace and use it for combustion.
It is a system of specially coated steel tubing.
Draft-Inducing Fan
Condensing furnaces, like many conventional furnaces, use a draft-inducing fan andpressure switch.
Furnaces and Boilers.Department of Energy.
