5322625-UIM-A-0417
Johnson Controls Unitary Products
25
5.
Once the correct BTU (kW) input has been established, turn the
gas valve to OFF, and turn the electrical supply switch to OFF. Then
remove the flexible tubing from the gas valve pressure port, and
tighten the pressure port plug using the 3/32” (2.4 mm) hex head
wrench.
6.
Turn the electrical and gas supplies back on. With the burners in
operation, check for gas leakage around the gas valve pressure
port. Use an approved non-corrosive gas leak detection fluid or
other non-flammable leak detection methods to accomplish the leak
check.
Adjust as follows:
1.
Remove the cap from the valve body. See Figure 11 for location.
2.
To decrease the gas pressure, turn the adjusting screw counter-
clockwise.
3.
To increase the gas pressure, turn the adjusting screw clockwise.
Adjustment Of Temperature Rise
After about 20 minutes of operation, determine the furnace temperature
rise. Take readings of both the return air and the heated air in the ducts
about six feet from the furnace where they will not be affected by radi-
ant heat.
The temperature rise (or temperature difference between the return air
and the heated air from the furnace) must lie within the range shown on
the rating plate and the data in Table 6.
After the temperature rise has been determined, the CFM can be calcu-
lated as follows:
Direct Drive Blower
All units have direct drive, enhanced ECM blower motors.
MANIFOLD PRESSURE “U” TUBE CONNECTION
FIGURE 12:
Reading Gas Pressure
NOTICE
The correct manifold pressure for natural gas furnaces is 3.5 IWG.
The correct manifold pressure for propane (LP) is 10.0 IWG.
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*$6
35(6685(
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287/(735(6685(7$3
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6(1625
$
DANGER
The temperature rise, or temperature difference between the return
air and the supply (heated) air from the furnace, must be within the
range shown on the furnace rating plate and within the application
limitations shown in Table 7 “RATINGS & PHYSICAL / ELECTRICAL
DATA”.
The supply air temperature cannot exceed the “Maximum Supply
Air Temperature” specified in these instructions and on the furnace
rating plate. Under NO circumstances can the furnace be allowed to
operate above the Maximum Supply Air Temperature. Operating the
furnace above the Maximum Supply Air Temperature will cause pre-
mature heat exchanger failure, high levels of Carbon Monoxide, a fire
hazard, personal injury, property damage, and/or death.
!
BTUH Output
1.08 x CFM
OR
CFM =
BTUH Output
Degrees F Temp Rise =
1.08 x Degrees F Temp Rise
