Midco F400-33 - Manual (Page 6)

VIII INITIAL START UP AND ADJUSTMENT
WARNING: Ignition is automatic. Make spark
observations into combustion chamber only with
Main and Pilot Manual Shut-Off Valves closed. Con-
firm that gas utilization equipment does not contain
any accumulated gases. Purge as described below.
CAUTION: Cover plates, guards, and enclosures
must be maintained in place at all times except dur-
ing maintenance and service.
1.
Check the piping and valves for gas leaks. Apply
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. Make sure that the burner main and pilot gas lines
are completely purged of air. Do not purge into the
combustion chamber.
3. Make sure the burner power switch is off, Main and
Pilot Manual Shut-Off Valves are closed, and motor
is free to rotate. Reset flame safeguard and all limit
controls.
CAUTION: Make sure that the capacity range
of the installed spud and the combustion air-
shutter setting are suitable for the gas utilization
equipment. Refer to Section VII and Table 2.
4.
Turn on the burner power switch, and allow motor to
run through the pre-purge and ignition cycle. Check
the blower wheel for proper rotation. After a short
run, the flame safeguard will lock out, stopping
the motor. Wait one minute, then reset flame
safeguard.
5. Turn on pilot manual shut-off 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 ignition transformer. Quickly observe pilot
flame.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. Set pilot pressure to
achieve the largest stable blue flame with a base
that burns firmly within the pilot tip. The best
operating pressure is usually about 3.5"W.C.
Natural (2.25"W.C. Propane). If pilot fails to light see
sections IX and XI.
6. Test for ignition and stability. Cycle the burner
several times with both open and closed air shutter.
Ignition and flame safeguard response will be
prompt with a good flame. Check flame following the
instructions provided by the flame safeguard
manufacturer.
WARNING: Repeated unsuccessful attempts to
light may result in accumulated gases in gas utiliza-
tion equipment and chimney. To prevent these gas-
es from reaching an explosive level, periodically
purge the gas utilization equipment and chimney as
described above.
7.
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 pilot valve
should be broken immediately.
8. Turn off line switch to stop the burner. Reset flame
safeguard. With On-Off burners, lock air shutter
= 360,000 BTU/Hr. = 360 MBH
= BTU/Hr.
-6-
wide open. On modulating burners, remove wires of
modulating controller from and "W" terminals on
the modulating motor and jumper terminals "R-B" to
drive input adjuster to high fire position when
energized. On 2-step burners, jumper terminals "3-
4" on valve actuator valve will open to high fire
position when energized. main flame ignites. Slowly
continue opening the Main Manual Shut-Off Valve to
the wide open position when energized.
9. To make a preliminary setting of the burner input,
determine the manifold gas pressure required from
Table 3 and adjust the main gas pressure regulator
accordingly. See Section XI.
10. 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.
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
10
11. Adjust combustion 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 gas.
12. The primary air adjustment which affects the flame
length has been set wide open for average
conditions. Decrease the primary air if a longer,
softer flame is desired.
13. Check the operation of the burner; start and stop it
several times with the thermostat or operating
control.
14. With the burner running, check the operation of all
limit and associated controls.
15. PERFORM THE FOLLOWING FINAL
ADJUSTMENTS for combustion and flue gas
temperatures. Take the flue gas samples and
temperature immediately ahead of the draft control.
A.
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.
B. Make the final setting of the combustion air
shutter by checking the flue gases with an
ORSAT or similar combustion testing instrument.
The carbon monoxide content should conform to
local codes, or, in their absence to the level
specified in the Unites States or Canadian
Standard referenced on the front cover of this
manual. The carbon dioxide content should
be approximately 9.5% for NATURAL and
12.1% for PROPANE, or within the limits
prescribed by local codes.
16. Check the draft control to make sure there is no
spillage of flue products into the room.