5168274-BIM-I-1121
22
Johnson Controls Ducted Systems
Field Installed Electric Heat Accessories
These field-installed heater accessories can be wired for single
point power supply.
These CSA approved heater accessories shall be located
within the central compartment of the unit with the heater
elements extending into the supply air chamber.
Fuses are supplied, where required. Some kW sizes require
fuses and others do not. Refer to Table 8 for minimum CFM
limitations and to Table 6 for electrical data.
Options/Accessories
Electric Heat
Electric heaters are available as a factory-installed option.
These heaters mount in the heat compartment with the
heating elements extending into the supply air chamber. All
electric heaters are fused and intended for use with single
point power supply.
Economizer/Motorized Outdoor Damper Rain Hood
The instruction for the optional economizer/motorized damper
rain hood can be found in the rain hood kit. Use these
instructions when field assembling an economizer rain hood
onto a unit. The outdoor and return air dampers, the damper
actuator, the damper linkage, the outdoor and return air divider
baffles, and all the control sensors are factory mounted as part
of the “Factory installed” economizer option.
Power Exhaust/Barometric Relief Damper and Rain Hood
The instructions for the power exhaust/barometric relief damper
and rain hood can be found in the rain hood kit. The exhaust
fan, all supporting brackets, angles, and the wiring are factory
installed as part of the power exhaust option.
Economizer Sequences
Several functions can drive the economizer, including: minimum
position, free cooling, economizer loading, and minimum
outdoor air supply.
Economizer Minimum Position
The economizer minimum position is set during occupied mode
when outside air is not suitable for free cooling. The position of
the damper is set proportionally between the "Economizer
Minimum Position and the Economizer Minimum Position Low
Speed Fan" set points, in relationship to the VFD output
percentage. On a constant volume single speed supply fan
system both set-points should be set to the same value.
Free Cooling
Four types of free cooling options are available: dry bulb
changeover, single enthalpy, dual enthalpy changeover, and
Auto.
Dry Bulb Changeover
For dry bulb economizer operation, the outside air is suitable for
free cooling if the outside air temperature is 1°F below the
Economizer OAT Enable Setpoint
and
1°F below the Return Air
Temperature.
Type
Centrifugal
Centrifugal
Motor Sheave
1VP60
1VP60
1VP60
1VP60
Blower Sheave
BK120
BK100
BK110
BK090
Belt
BX81
BX78
BX78
BX75
Motor HP each
5
7.5
7.5
10
RPM
1750
1750
1750
1760
Frame size
184T
213T
213T
215T
FILTERS
Quantity - Size
4 - (16 x 25 x 2),
12 - (12 x 24 x 2)
1,2
4 - (16 x 20 x 2)
1,2
4 - (16 x 25 x 4),
2 - (20 x 24 x 4),
12 - (12 x 24 x 4)
3
4 - (16 x 20 x 4)
3
1. 2 In. Throwaway, Standard, MERV (Minimum Efficiency Reporting Value) 3.
2. 2 In. Pleated, Optional, MERV 8.
3. 4 In. Pleated, Optional, MERV 13.
Table 7: XA-15, XA-20 Physical Data (Continued)
Component
Models
XA-15
XA-20
Nominal Tonnage
15
20
Table 8: Electric Heat Minimum Supply Air
Size
(Tons)
Voltage
Minimum Supply Air (CFM)
Heater kW
18
36
54
72
-15
(15)
208/230-3-60
4500
4500
5000
5000
460-3-60
4500
4500
5000
5000
600-3-60
4500
4500
4500
4500
-20
(20)
208/230-3-60
6000
6000
6000
6000
460-3-60
6000
6000
6000
6000
600-3-60
6000
6000
6000
6000
