12
9. Set thermostat in "OFF" position and turn duct furnace control switch "ON" (manual).
10. Check all fan motors for correct rotation. If incorrect, reverse rotation (see motor
nameplate wiring diagram).
11. Check the amperage draw of each motor. Refer to rating plate for Full Load Amps
(FLA). If actual motor load is significantly different than rated, take corrective action.
12. Re-check voltage at duct furnace disconnect switch with the duct furnace running. If the
power is not within 10% of rated, shut duct furnace down and consult electric utility
company. Voltage should be within 2% on all phase to phase readings when compared
to each other. A 2% voltage difference could cause as much as a 20% current
imbalance.
13. Ensure that the flue is in place and as noted in 2.7 line 10 Exhaust Stacks and Venting.
14. Set the operating controls, thermostat, remote panel switches, etc., to allow heating
operation of the duct furnace.
15. Initial start up has a tendency to relieve the tightness of nuts, bolts and set screws. Re-
check for tightness of hold down bolts, all set screws and keys, and tighten if necessary
after approximately eight (8) hours of continuous operation.
3.2 Combustion Operation
CAUTION
DO NOT relight pilot or start burner when the heat exchanger is very hot, full of gas.
NOTE: When starting up the duct furnace for the first time or if the duct furnace has been
shut down for an extended period of time the same start-up procedures, as outlined in
sections 3.2 and 3.3, should be followed.
1. Refer to burner manufacturer’s Installation, Operation, and Maintenance Instructions for
proper set-up, operation, and settings. Turn on the main and pilot (if applicable) manual
shutoff valves upstream of the firing rate shutoff valve and check for leaks on duct
furnace piping, correct leaks.
2. Check the gas supply pressure to the duct furnace, making sure it does not exceed the
maximum on the duct furnace rating plate.
3. Connect test instruments, meters, and thermometers on the furnace and controls to
measure and record the appropriate data.
4. Close the main manual valve, leaving the pilot open (if applicable).
5. Set the thermostat at highest setting and energize the heating control - burner motor
starts, closing the air switch and energizing the ignition control.
6. With power supplied to the ignition controller and all the safety limiting devices are
satisfied, a 30 - 90 second pre-purge will start, the pilot valve (if applicable) or main gas
valve is energized and a 6-15 second trial to ignite. If the flame sensing probe fails to
prove the pilot or main flame, it de-energizes the spark igniter and the controller will
lockout on flame failure (10-30 seconds). This safety step is performed to establish the
flame sensing, and test any of the safety devices before main burner light off.
