Posted by Harold Kestenholz - Hydronic Network on December 21, 2001 at 12:20:50:
In Reply to: furnace purging posted by Afdmello on December 21, 2001 at 10:39:34:
Pre and post-purge is part of the burning cycle. This is done to sweep the interior of combustibles so the only source of flame is from the air-fuel mixture at the burner. Unburned fuel can continue to evaporate and mix as dust in the interior after the burning cycle; the purge reduces the risk of uncontrolled ignition and explosion.