16
5-572.10
START-UP PROCEDURE
Refer to page 58 for the Start-up Checklist.
1. Turn off power to the unit at the disconnect switch. Check
that fuses or circuit breakers are in place and sized
correctly. Turn all hand gas valves to the “OFF” position.
2. Remove the blower exterior panels and open the electrical
compartment door.
3. Check that the supply voltage matches the unit supply
voltage listed on the Model Identification plate. Verify that
all wiring is secure and properly protected. Trace circuits to
insure that the unit has been wired according to the wiring
diagram.
4. Check to insure that the venting system is installed and
free from obstructions.
5. Check to see that there are no obstructions to the intake
and discharge of the unit.
6. Check the belt tension and sheave alignment. Refer to
Blower Adjustments for proper belt tension.
7. Check bearings for proper lubrication. For units provided
with pillow block bearings (See Model Nomenclature),
refer to Lubrication Recommendations for requirements.
8. Check to make sure that all filters are in place and that
they are installed properly according to direction of air flow.
9. Perform a visual inspection of the unit to make sure no
damage has occurred during installation.
10. Turn on power to the unit at the disconnect switch. Check
to insure that the voltage between duct furnace electrical
box terminals 1 and 2 is 24V.
11. Check the thermostat, ignition control, gas valve, and
supply fan blower motor for electrical operation. If these do
not function, recheck the wiring diagram. Check to insure
that none of the Control Options have tripped.
12. For units with a return air damper, the return air damper
linkage needs to be adjusted. Refer to Damper Linkage
Adjustment.
13. Check to make sure that the damper opens properly
without binding.
14. Check the blower wheel for proper direction of rotation
when compared to the air flow direction arrow on the
blower housing. Blower wheel rotation, not air movement,
must be checked as some air will be delivered through the
duct furnace with the blower wheel running backwards.
15. Check the blower speed (rpm). Refer to Blower
Adjustments for modification.
16. Check the motor speed (rpm).
17. Check the motor voltage. On three phase systems, check
to make sure all legs are in balance.
18. Check the motor amp draw to make sure it does not
IMPORTANT
1. To prevent premature heat exchanger failure, observe
heat exchanger tubes by looking at the heat exchanger
through the field installed access openings in connecting
ductwork or the unit access doors where viewing the heat
exchanger is possible. If the bottom of the tubes become
red while blower and duct furnace are in operation, check
to be sure the blower has been set to the proper rpm for
the application. Refer to page 16 for Blower Adjustments.
2. Start-up and adjustment procedures should be performed
by a qualified service agency.
exceed the motor nameplate rating. On three phase
systems, check all legs to insure system is balanced.
19. Recheck the gas supply pressure at the field installed
manual shut-off valve. The minimum inlet pressure should
be 6" W.C. on natural gas and 11" W.C. on propane gas.
The maximum inlet pressure for either gas is 14" W.C. If
inlet pressure exceeds 14" W.C., a gas pressure regulator
must be added upstream of the combination gas valve.
20. Open the field installed manual gas shut-off valve.
21. Open the manual main gas valve on the combination
gas valve. Call for heat with the thermostat and allow the
pilot to light for intermittent pilot ignition. If the pilot does
not light, purge the pilot line. If air purging is required,
disconnect the pilot line at outlet of pilot valve. In no case
should the line be purged into heat exchanger. Check the
pilot flame length (See Pilot Flame Adjustment).
22. Once the pilot has been established, check to make sure
that the main gas valve opens. Check the manifold gas
pressure (See Main Gas Adjustment) and flame length
(See Air Shutter Adjustment) while the supply fan blower is
operating.
23. Check to insure that gas controls sequence properly (See
Control Operating Sequence). Verify if the unit has any
additional control devices and set according to the
instructions in the Control Options.
24. Once proper operation of the unit has been verified,
remove any jumper wires that were required for testing.
25. Close the electrical compartment door.
26. Replace all exterior panels.
Pilot Burner Adjustment
The pilot burner is orificed to burn properly with an inlet
pressure of 6-7" W.C. on natural gas and 11-14" W.C. on
propane gas. Final adjustment must be made after installation.
If the pilot flame is too long or large, it may cause soot and/
or impinge on the heat exchanger causing failure. If the pilot
flame is too short, it may cause poor ignition or result in the
controls not opening the combination gas control. A short flame
can be caused by a dirty pilot orifice. The pilot flame should be
observed periodically to assure trouble-free operation.
To Adjust the Pilot Flame
1. Create a call for heat from the thermostat.
2. Remove the cap from the pilot adjustment screw. For
location, see the combination gas control literature supplied
with unit.
3. Adjust the pilot length by turning the screw in or out
to achieve a soft steady flame 3/4" to 1" long and
encompassing 3/8"-1/2" of the tip of the flame sensing rod
(See Figure 16.1).
4. Replace the cap from the pilot adjustment screw.
3/4" to 1"
Start-Up Procedure
Figure 16.1 - Correct Pilot Flame
Flame Sensing Rod