PAGE 19 of 41 HG-1-1401A GAS-FIRED HEATER
© SAMUEL JACKSON, INCORPORATED 2005 ALL RIGHTS RESERVED
AIR FLOW SWITCH
-- The fan will turn on for this test. The velocity pressure should
be at about 0.4" (1.0 cm). If necessary, adjust this by adjusting the vanes which constrict
the passage of air just ahead of the burner head. They are just inside the burner access
door. Bring the vanes closer together to increase velocity pressure VP or farther apart to
reduce it. Make the adjustment the same on all vanes.
If VP is too low, the flame might be yellowish, and the air flow switch not so responsive.
If VP is too high, the flame will burn with a roar at high outputs or may be difficult to
light. On higher air volume systems where the velocity cannot be reduced to 0.4" with the
shutters, remove the vanes completely and store them in the burner cabinet.
Burner body access door shown removed
allowing access to the air vanes.
Adjust vanes
evenly