Midco 400B-02 - Manual (Page 7)

1. Check the burner piping and valves for gas leaks by applying a weak liquid soap solution
to unions and joints with the gas supply on. Leakage will be indicated by the appearance of
soap bubbles. Locate and correct all gas leaks before proceeding.
WARNING: DO NOT USE OPEN FLAME.
2. Purging the air from the gas supply line at this step will expedite the first light-off.
CAUTION: Purge outside the building. Do not purge into the gas utilization
equipment.
3. To purge the gas utilization equipment and chimney of any accumulated gases, turn
Manual Gas Cock Knob on the Combination Valve to OFF, turn burner power on and set oper-
ating control to ON or thermostat to call for heat. Let the blower run long enough to accomplish
four air changes, but not less than five minutes.
4.
CAUTION: Make sure that the capacity range of the installed spud and the
preliminary primary air shutter settings are suitable for capacity rating of the
gas utilization equipment. Refer to Section VII and Table 3.
5. Stop motor by setting operating control to OFF or thermostat below room temperature.
6. Turn Manual Gas Cock Knob on Combination Valve to PILOT and depress knob, or red
button if so equipped. Hold firm and light pilot by depressing piezo ignitor button several times.
Pilot should light. Pilot may be viewed through Peep Sight located in Back Plate (See Figure
6). Failure to light is probably due to air in pilot gas line. Attempt several relights. Then, if nec-
essary, refer to Trouble Chart or Section IX to isolate the problem.
WARNING: Repeated unsuccessful attempts to light pilot will result in accu-
mulated gases in gas utilization equipment and chimney. To prevent these
gases from reaching an explosive level, periodically purge the gas utilization
equipment and chimney as described in Step 3 above.
7. With pilot lit, wait one minute; then release Manual Gas Cock Knob on Combination Valve,
or red button if so equipped, and turn to ON. if a pilot goes out when knob is released, turn to
OFF then PILOT and repeat purging and pilot lighting instructions detailed above. Incorrect
pilot flame gas pressure may prevent proper heating of thermocouple causing the pilostat safe-
ty control to drop out. Refer to Section IX for pilot adjustment.
8.
Turn operating control to ON or set thermostat above room temperature. Main flame
should come on when the motor reaches operating speed. If not, refer to Trouble Chart. To
make a preliminary setting of the burner input, determine the manifold gas pressure required
from Table 3 and adjust the Combination Valve Pressure Regulator accordingly. See SectionXI.
9.
To determine the firing rate for NATURAL gas, 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.
Then divide by 1,000 for MBH value
For PROPANE gas, consult your supplier for method of determining firing rate.
10. Readjust the primary air shutter to provide a quiet, soft blue flame with well defined orange
and yellow tips for NATURAL gas or with well defined yellow tips for PROPANE.
11. Check the operation of the burner; start and stop it several times with the thermostat or
operating control.
12. With the burner running, check the operation of all limit and associated controls.
13. PERFORM THE FOLLOWING FINAL ADJUSTMENTS for combustion and flue gas tem-
perature. Take the flue gas samples and temperature immediately ahead of the draft control.
A. Check the draft control to make sure there is no spillage of flue products into the room.
B. Make the final setting of the primary air shutter by checking the flue gases with an
ORSAT or similar combustion instrument. The carbon monoxide content should conform
to local codes, or in their absence to the level specified in the United States or Canadian
Standard referenced on the front cover of this manual; and the carbon dioxide content
should be approximately 9.5% for NATURAL and 12.1% for PROPANE, or within the
limits prescribed by local codes.
C. The flue gas temperature should be above 325°F but not exceeding 550°F. Excessive
flue gas temperatures will result in low efficiencies. Low flue gas temperature may cause
excessive condensation. Reset gas input if necessary to adjust stack temperature.
14. FILL OUT THE INSTALLATION ADJUSTMENT DATA TAG and affix to the burner or gas
utilization equipment.
Note: For subsequent normal starting and shut-off procedure, refer to CONSUMER
INSTRUCTIONS or the instruction plate mounted on the burner.
7
VIII Initial
StartUp/Adjustment
3600 x test dial size x BTU value
No. of seconds for one rev. test dial.
= BTU/Hr.
3600 x 1 x 1000
20
= 180,000 BTU/Hr. = 180 MBH Example: