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5. Adjust air handler high fire gas pressure.
•
Determine the high fire gas pressure by
adding the manifold pressure for maximum
input (from the rating plate) and the burner
negative pressure (from the measurement
made in the burner pressure section of this
procedure). Record this value for use in
adjustment step.
For example:
Differential pressure= -1.0 in wc
Maximum manifold pressure (from rating plate)= 2.0
in wc
High fire gas pressure= 2.0 + (-1.0) in wc
High fire gas pressure= 1.0 in wc
•
Force the burner into high fire. Refer to the
burner mode setting chart on Page 65,
Table 17, for the specific amplifier and action
•
Set the pressure at the burner side of the
modulating valve to the calculated value
(from the begining of this step), by removing
high fire adjustment cap and rotating the
regulator adjustment screw. A clockwise
rotation increases manifold pressure.
Temperature rise should not exceed
maximum as listed on Page 66, Table 18.
For under a million BTU input, the high fire
gas pressure is set by adjusting the
regulator upstream of the M611 valve. See
Page 68, Figure 37.
•
Reconnect any wires that were used for
adjustment.
6. Adjust recirculating mode or reduced air vol-
ume high fire gas pressure
•
This adjustment is required for and only
applies to AM and VAV style units.
•
Force the unit into high fire and maximum
recirculation for AM style or minimum air
volume for VAV style. Refer to the burner
mode setting chart on Page 65, Table 17 for
specific amplifier and action required to
place it into high fire.
•
Measure the recirculation temperature rise
and compare it to Page 66, Table 18.
•
The resistor on the reduced flow switch
(mounted inside the control enclosure) may
need adjustment until recirculation
temperature rise is obtained.
•
Return unit to normal operating conditions.
• Reconnect any wires that were removed for
adjustment.
7.
Maximum discharge temperature is 160° F
(71° C) for models approved to Z83.4 and
Z83.18 (see ETL Standard). For models
approved Z83.25 (see ETL Standard), the
maximum discharge temperature is 200° F
(93° C).
8. Low fire adjustment
•
NOTE: High fire gas pressure must be set
BEFORE adjusting low fire. There are three
critical items to consider before adjusting
low fire:
A. Low fire adjustment does not regulate
gas pressure.
B. If the low fire adjustment screw is set to
maximum, high fire regulation problems
will occur.
C. The burner control system must be
forced into low fire per the "Burner Mode
by Amplifier Type" table. See Page 65,
Table 17.
•
Low fire is set at the MR212 valve using the
adjustment screw under the low fire
adjustment cap screw (loosen locking screw
before adjustment), See Page 67 , Figure 35,
or on the M611 valve using the brass
adjusting screw on the front side, See Page
68, Figure 36. The burner must be forced
into low fire first. Then rotate the adjustment
screw until there is a continuous blue ribbon
across the entire burner. A counter
clockwise rotation increases the flame size.
Low fire temperature rise must not exceed
12° F (7° C). Tighten locking screw when
finished.
•
Reconnect any wires that were removed for
adjustment.
9. Once gas pressure and high/low fire adjust-
ments are made, the gas setup is completed.
All taps and instruments must be removed and
all caps and plugs must be replaced.
Table 17: Burner Mode by Amplifier Type
Amplifier Type
High Fire Mode
Remove wire from terminal
Series 14
#4 on the amplifier
Remove wires from termi-
Series 44
nals #2 and #4 on the
amplifier
SECTION 20: S
-
P
TART
UP
ROCEDURES
Low Fire Mode
Remove wire from ter-
minal #8 on the ampli-
fier
Remove from terminal
#9 on the amplifier
65
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