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6
SECTION V - UNIT START-UP
Close or replace all doors and service panels.
Turn main disconnect switch off. Verify the incoming line
voltage matches the unit nameplate rating. If the voltage is
over ±10% of nameplate rating or phase voltage unbalance
is over 2%, notify the contractor or power company.
Turn Heat OFF/ON switch to the OFF position. Turn main
disconnect switch on. Turn Fan OFF/ON switch to the
ON position. Damper opens. Blower fan turns on.
Turn Fan OFF/ON switch to OFF position and check sup-
ply blower for proper rotation.
NOTE: To change rotation of the blower, simply
interchange any two (2) of the line leads of the
motor starter for three (3) phase motors. Refer to
motor nameplate for reversing single (1) phase
motors.
Turn Fan OFF/ON switch to the ON position. Check for
proper blower rpm. Check that all motor amp draws do
not exceed nameplate ratings, and the overload relay is set
to the motor nameplate amperage.
Check dampers for proper operation. Be sure they operate
freely, and the linkage does not bind.
Make sure all manual gas shut-off valves are in the closed
position.
Turn Heat OFF/ON switch to the ON position. Blower
fan will run.
Turn Fan and Heat OFF/ON switches to OFF position.
Setting Burner
NOTE: To adjust gas pressure on supply lines where
a regulator has been installed (to reduce the inlet
pressure to 1/2 PSIG or less), remove dust cap of main
gas regulator and turn adjusting screw clockwise to
increase pressure, or counter-clockwise to decrease
pressure.
Set all thermostats to call for heat. Set inlet ductstat (if
applicable) above outside air temperature.
Connect a DC microammeter between the SENSE terminal
and the flame rod sensing wire.
Turn Fan and Heat OFF/ON switches to ON position.
Open inlet manual gas shut-off valve slowly. Reset high and
(if applicable) low gas pressure switches. Check main gas
line for leaks using soap solution.
Unit will run for 5 seconds before ignition trial.
NOTE: 3 OR 4 TRIALS MAY BE NEEDED TO
PURGE AIR FROM GAS LINE.
United Technologies Electronic Controls Spark Ignitor
Watch microammeter carefully. The reading should be at
least 5.0 microamps. If the reading is too low, slowly turn
the low-fire adjustment on the modulating valve in or out
until satisfactory readings are obtained. When adjusting
low fire, there should be a continuous flame along the
entire burner length without any blowout spots.
Refer to Maxitrol Valve Adjustment instructions
in Section IX for setting high and low fire gas
pressure settings.
When the flame is adjusted, shut the unit off by turning the
Fan and Heat switches to OFF.
Setting Main Flame
Install manometer at test port on the last tee of the burner
manifold or modulating valve.
Slowly open all manual gas shut-off valves.
Restart unit. After main gas valves open and burner lights
check gas lines for leaks.
Adjust high gas pressure reading (from manometer) to
match firing rate shown on unit nameplate.
Adjust the high and low fire setting according to the
Maxitrol Valve Adjustment instructions in Section IX. The
high fire setting must not exceed the pressure stated on
the rating plate.
When adjusting low fire, there should be a continuous flame
along the entire burner length without any blow out spots.
Main flame is now set. Recheck the microamp signal on the
ignition control throughout the full burner input range. Re-
check low fire setting. Cycle unit 2 or 3 times to insure
good ignition.
Safety Controls Check
A. High Temperature Limit and Firestats – These limit
controls are not adjustable and are checked by the
factory. Reset the red button(s) to be sure they are
ready for operation. Contact the factory if these switch-
es fail to reset.
B. Ignition Control - Operate unit in Heat mode. After
flame has been established, close last manual gas valve
before main burner.The ignition control must trip out
within 15 seconds. Reset the ignition control by turning
the HEAT switch to the OFF position.