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I-EEDU (02-21) 150492-A
Operating Gas Valve Maintenance
⚠ WARNING ⚠
The operating valve (combination valve) is the prime safety shutoff. To ensure positive closure, all
gas supply lines must be free of dirt or scale before connecting to the unit.
Remove external dirt accumulation from the valve and check wiring connections . Check operational pressure as
follows:
1 . Turn OFF manual valve to prevent flow to combination valve .
NOTE: A manometer (fluid-filled gauge) with an inches water column scale is recommended for
gas pressure measurement rather than a spring-type gauge due to the difficulty of maintaining
the calibration of a spring-type gauge.
2 . Connect manometer to 1/8-inch inlet pressure tap on valve (see
) .
3 . Observe manometer reading for 2 to 3 minutes . No gas pressure should be indicated on manometer .
4 . If manometer indicates any gas pressure, field-installed manual gas valve must be replaced or repaired before
combination gas valve can be checked .
5 . If manometer does not indicate gas pressure, slowly open field-installed manual gas valve .
6 . After manometer reading indicates that gas pressure has reached equilibrium, close manual shutoff valve and
observe gas pressure . Manometer reading should indicate no loss of gas pressure . If loss of pressure is indicated,
replace combination gas valve before placing heater in operation .
Burner Rack and Pilot Maintenance
1. Remove burner rack assembly:
a . Turn OFF gas supply .
b . Turn OFF electric supply .
c . Remove two screws from each side of bottom rear panel located on manifold side of furnace and remove panel .
d . Disconnect valve’s electric leads and mark for correct reconnection .
e . Uncouple gas supply union .
f . Remove two sheet metal screws in bottom of burner rack assembly and pull drawer-type burner rack out of
furnace .
2. Disassemble burner rack:
a . Remove screws at rear of burner drawer and remove flash carryover system .
b . Remove burner hold-down clamp under pilot inside burner drawer .
c . Pull main burners away—horizontally—from injection opening and lift out .
3. Clean pilot:
⚠ CAUTION ⚠
Do not ream the orifice.
NOTES:
• The pilot is located (see
, DETAIL A) under the aeration panel on the control end of the
burner tray and is accessible only after the burner rack assembly has been removed.
• If pilot flame is short and/or yellow, check pilot orifice for blockage caused by lint or dust
accumulation.
• When re-installing a vertical spark pilot, be sure to include the pilot hole cover plate (see
, DETAIL B).
