Midco Unipower G-Series - Manual (Page 9)

5 . Set blower air shutter wide open. On 2-Step and Modulating burners, disconnect air shutter
connecting rod at blower shutter shaft, and lock shutter wide open.
6 . Turn on the line switch, and allow motor to run through the pre-purge and ignition cycle. Check
the blower wheel for proper rotation. Viewing from the motor shaft end (Blower Inlet side),
rotation should be counter clockwise. After a short run, the flame safeguard will lock out, stopping
the motor. Wait one minute, then reset the flame safeguard.
7 . Turn on pilot manual valve. With Main Manual Shut-Off Valve still closed, turn on main line switch.
Motor will start. When pre-purge period has elapsed, flame safeguard will energize pilot solenoid
valve and spark generator. When flamerod senses pilot flame, the flame safeguard will energize
the main valves. No main flame will occur due to closed Main Manual Shut-Off Valve. Quickly
observe pilot flame, if no flame or if weak, screw in pilot regulator adjustment. If the flame is rich
and floating from the pilot tip, back off the pilot regulator. Set to achieve the largest stable blue
flame with a base that burns firmly within the pilot tip. The best operating pressure is usually 3
1 / 2 "
to 4" W.C. Test for ignition and stability several times, cycling the burner with both open and
closed air shutter. Ignition and relay response will be prompt with a good flame. Check flame
signal with a DC voltmeter. Pilot should be set to yield the highest steady reading, at least 2 volts
DC and as high as 5 volts. Plug-in jacks are provided in the amplifier section of the flame safeguard
for voltmeter connection.
8 . Check operation of the electronic flame detection circuit by turning off the pilot manual valve with
pilot burning and Main Manual Shut-Off Valve still closed. The circuit to the main automatic valve
should be broken when the pilot goes out.
* 9 . Turn off line switch to stop the burner. Rest flame safeguard. Set blower air shutter about 1 / 4
open. With On-Off and 2-Step burners, loosen gland nut on Butterfly Valve and temporarily lock air
shutter wide open (slot in shaft parallel to flow). On modulating burners, remove wires of
modulating controller from "B" and "W" terminals on the modulating motor. Jumper terminals
"R-B" to drive input adjuster to high fire position when energized. The high fire adjustment screw
on the input adjuster should be backed off to the wide open position. On 2-Step burners, jumper
terminals "3-4" on valve actuator so valve will open to high fire position when energized.
1 0 . Turn on main line switch. After the main valve is energized, slowly open Main Manual Shut-Off
Valve until the main flame ignites. Then opening the air shutter as required to maintain a suitable
flame, slowly open the Main Manual Shut-Off Valve to the wide open position or until, with the air
shutter wide open, the main flame becomes excessively rich.
* 1 1 . The manifold pressures shown in Tables 1 and 5 may be used to determine the approximate gas
input settings. The gas input for Natural gas models can be determined by timing the gas meter.
Accurately time test dial for the number of seconds for one revolution and use the following
formula. All other gas utilization equipment must be off.
CAUTION: The manifold pressures shown in tables are both the blower air pressure
and the gas pressure. Air shutter adjustments will effect manifold pressure and
i n p u t .
The effective gas pressure is the difference between the total pressure which registers when the
gas valve is closed. Clock the meter gas rate and (if necessary) reset the main regulator to control
gas flow at about 10% over burner rating or over desired input with Main Manual Shut-Off Valve
wide open. Turning the adjustment screw clockwise on main regulator increases pressure and flow
rate, reverse decreases. Do not adjust the regulator past the point where no further change in gas
flow is noted. For On-Off and 2-Step burners, "close" off Butterfly Valve to the desired maximum
input rate, secure gland nut, and replace cap. For Modulating burners, screw in the high fire
adjustment screw on the input adjuster to set the maximum firing rate. Reset the blower air shutter
to provide fairly long flame, blue at the burner face, orange or red at the tips. Flashes of yellow
may be visible. Close firing door for a few seconds; then open and quickly observe fire. If a purple
haze is noted at the rear of the firebox, lack of air is indicated and air shutter should be opened
wider. Refer to Table 1 if the manifold pressure is to be used as a guide to gas input.
1 2 . Check the flue gas temperature at the boiler flue outlet. It should be above 325° but not exceeding
550°. Excessive flue temperatures result in low efficiencies. Low flue gas temperatures may cause
excessive condensation. Reset input if necessary to adjust stack temperature; or if temperature is
too low, portions of the heat exchanger surface can be blocked off with insulating firebrick.
1 3 . Make the final setting of the air shutter by checking the flue gases with an "Orsat" or similar
combustion testing instrument. There should be no carbon monoxide and the carbon dioxide
content should be approximately 9.5% for NATURAL and 12.1% for PROPANE, or within the
limits prescribed by the local fuel supplier.
VII Initial Start-Up
Continued
9
3600 x test dial size x BTU value
no. of seconds for one rev. test dial
Then divide by 1,000 for MBH value.
Example: 3600 x 1 x 1000
5
For Propane gas, consult your supplier for method of determining firing rate.
= BTU/HR.
= 720,000 BTU/HR.=720 MBH