Midco Unipower MPG Series - Manual (Page 13)

5) Loosen the linkage connecting rod at the ball joint (7/16” wrench) nearest to the
motorized actuator and the U clamp (5/16” deep socket) of the motorized actuator,
and set:
a. air shutter at minimum opening position
b. gas flow control valve at 2 O’clock
c. both crank arms at 7 O’clock
Note: Linkage connecting rod should be parallel to blower scroll housing face.
6) Turn the burner power On-Off switch to ON and allow the motor to run through the
pre-purge and ignition cycle. Check the blower wheel for proper rotation. Viewing from
the blower inlet screen, rotation should be counter-clockwise. After approximately 90
seconds, the flame safe guard will lock out, stopping the motor.
7) Open the pilot manual gas valve leaving the main manual gas valve closed. Reset the
flame safe guard. Motor will start. When the pre-purge period (90 seconds) has
completed, the flame safe guard will energize the pilot solenoid valve and the spark
generator. The pilot should be ignited and the flame rod or UV scanner senses the pilot
flame. Adjust the pilot gas pressure to reach the strongest and most stable pilot flame
signal. See Table 8 for preliminary pilot gas pressure settings. Test several times for
pilot ignition, stability and flame sensing signal.
8) Measure the main gas differential pressure by installing a digital manometer. One gas
pressure tap should be installed in the downstream port of the downstream automatic
main gas safety shutoff valve. The second gas pressure tap should be installed in the
manifold test tap that is located just upstream of the gas flow control valve. See Table
7 for initial differential manifold gas pressure & air shutter settings.
9) Slowly open the main manual gas valve with the main valves energized and watch
through the peep sight glass located on the back of the pilot drawer assembly to make
sure that the main flame ignites.
10) Check the flue gas readings with a combustion gas analyzer. Slowly and manually
adjust the gas flow control valve and/or air shutter to achieve the correct burner low fire
firing rate and proper preliminary flue gas readings (approximately 4 - 5% O
2
and
approximately 9 - 9 ½% CO
2
).
11) Slowly and manually adjust the gas flow control valve and/or air shutter to achieve the
correct burner high fire firing rate and proper preliminary flue gas readings
(approximately 4 - 5% O
2
and approximately 9 - 9 ½% CO
2
). Tighten the linkage
connecting rod at the ball joint (7/16” wrench) nearest to the motorized actuator.
12) Check the flue gas readings with a combustion gas analyzer. Adjust the regulator of the
main gas combination valve or the independent main gas pressure regulator and/or the
air shutter to achieve the correct burner high fire firing rate and proper flue gas
readings (approximately 4 - 5% O
2
and approximately 9½ - 10% CO
2
).
NOTE: For a full modulating burner, check the burner combustion performance at mid
range firing rate and adjust as necessary.
13) Turn the burner power On-Off switch to OFF. Manually move the gas flow control
valve, connecting rod and air shutter to the low fire position. Tighten the U clamp of the
motorized actuator. Move the adjustable stop block of the motorized actuator to the
3 O’clock position and lock it in place. At the Midco control cabinet terminal strips,
disconnect the signal input wires from the remote temperature controller. Place a
temporary jumper from terminal M2 to M3 (this simulates a call for high fire heat).
Note: Circuit from terminal strip 5 to 6 must be closed in order for the burner to fire.
14) Turn the burner power On-Off switch to ON. The burner should start and
sequence as follows:
a. 10 second initiation
b. 90 second pre-purge period
c. Pilot ignition, flame proving
d. Main flame ignition, low fire start
e. Main flame, high fire operation
15) If the measured high fire firing rate is less (more) than the desired value, turn the
burner power On-Off switch to OFF, move the adjustable stop block of the motorized
actuator up (down) and try again until reaching the desired high fire firing rate.
13
XVI Initial
Start Up
Instructions
2-Stage and Full
Modulating Burner
Continued
Part 1 Installation