Pulse furnace - how it works

Heating · Condensing Furnaces · printed page 134 (PDF page 135)

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Book index entries

How It Works Pulse – Furnace How It Works Condensing Gas Furnaces Furnace – Condensing Gas Furnace – Condensing

Text in the illustration

tailpipe
combustion chamber
air
gas
air intake flapper valve
gas intake with flapper valve
igniter (spark plug)
A
air and gas are drawn into the combustion chamber through the flapper valves
shockwave
B
the air/gas mixture is ignited by the spark plug, creating the first pulse
the pulse closes the gas and air flapper valves and pushes the combustion products out through the tail pipe
reflected shockwave
air/gas mixture
C
as the shockwave leaves the combustion chamber, negative pressure is created that draws open the flapper valves and draws more air/gas mixture into the combustion chamber
meanwhile, at the end of the tailpipe, the shockwave is being reflected back to the combustion chamber
D
when the reflected shockwave reaches the combustion chamber, it is hot enough to ignite the air/gas mixture without the aid of the spark plug
this second pulse closes the flapper valves, sends the combustion products down the tailpipe and starts a repeating, self-sustaining combustion process
adapted from LENNOX illustration

Generated explanation

Four schematic stages show the operating cycle of a pulse gas furnace, with a combustion chamber connected to a long, looping tailpipe. In stage A, air and gas enter through flapper valves near the spark-plug igniter at the base of the chamber. In stage B, spark ignition produces a pressure pulse that closes the inlet valves and drives combustion products into the tailpipe. Stage C shows the departing shockwave creating negative pressure that opens the valves to admit a fresh air/gas mixture, while the wave reflects from the tailpipe end. In stage D, the returning hot shockwave ignites the fresh mixture without the spark plug, establishing a repeating, self-sustaining combustion cycle.

Components

combustion chamber tailpipe air intake air intake flapper valve gas intake gas intake flapper valve spark-plug igniter

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