Vent damper

A vent damper for a hot water heater having a main burner, an exhaust port for evacuation of the exhaust gases generated by said main burner, a pilot burner light or other burner starting means, and an exhaust duct attached to said exhaust port for venting said exhaust gases, said vent damper comprising:

• poppet means which is generally conically shaped and disposed between said exhaust duct and said exhaust port for controlling the flow of gasses through said exhaust port, said poppet means having means for mating with a guide means and being movable between an upward first position providing a predetermined maximum flow opening coupling said exhaust port and said exhaust duct, and a downward second position providing a predetermined minimum flow opening coupling said exhaust port and said exhaust duct, said minimum flow opening being small enough to substantially limit the flow of ambient gases but large enough to allow passage of gases from said pilot light or other burner starting means;
• guide means disposed coaxial with said exhaust port and operative to align said poppet means therewith and to guide said poppet means as it is moved between said first position and said second position;
• and
• shield means disposed above said poppet means and configured to nest therewith when said poppet means is in said first position, said shield means being supported by said guide means and serving to deflect exhaust duct downdrafts away from said poppet means,
• whereby when said main burner is operating, the exhaust gas moves said poppet means upward toward said first position to permit said exhaust gases to flow through said exhaust port and around said poppet means to said exhaust duct, and when said main burner is not operating, said poppet means returns downward to said second position to limit the flow of ambient and pilot burner gases from said exhaust port into said exhaust duct.