Page 16
LGH/LCH420, 480, 540, 600
FIGURE 21
FIELD WIRING HOT GAS REHEAT UNITS
(Using A Humidity Sensor With More
Than 150 Ft. Wire Runs)
ISOLATED 24V
TRANSFORMER
9
8
P298
J298A
1
2
B
3
4
C
5
6
7
D
10
A91
VIN
VO
GND
R
C
AI-1
HUM
TMP
DO-1
C
DI-1
DO-2
NOT
CONNECTED
NOT
CONNECTED
DRAIN
A55 UNIT
CONTROLLER
VFD Supply Air Blower Start-Up
This section is used when the unit is equipped with an
optional variable frequency drive (VFD) supply air blower.
Install static pressure transducer before start-up; see
Optional Supply Air VFD section in this manual.
A-Set Static Pressure Setpoints
Refer to the Unit Controller manual provided with the unit.
1- Open all zone dampers and/or boxes.
2- Locate the Unit Controller in the control box. Refer to
the dimension illustration in the front of this manual.
Refer to the Unit Controller Installation and Setup Guide to
change the System Mode. Use the menu navigation arrows
and select button; see
Settings - Install
.
3- Apply power and use the Unit Controller to start the
blower. Press the menu navigation arrows and select
button to initiate the blower. Refer to the
Service - Test
menu in the Unit Controller manual. Allow blower
speed to stabilize.
4- Locate TB18 under Unit Controller. Read the DC
voltage at terminals 6 (+) and 10 (-). Divide reading by
2 to determine system static pressure.
TB18-6 & 10
Voltage
__
.
.
2
= System Static “w.c.
5- Static pressure setpoints are factory-set at 1”w.c.
Change the setpoints to match the static calculated in
the previous step or to design specifications. Refer to
the
Setting - Control - ECTO
menu in the Unit Controller
manual. In addition, reference tables 2 and 3. Record
new setpoints in table 4.
6- The Unit Controller is factory-set to shut the unit off if
duct pressure exceeds 2.0”w.c. longer than 20
seconds. This pressure can be changed using ECTO
parameter 0.21. Refer to the Unit Controller manual.
TABLE 2
VFD SUPPLY AIR STATIC PRESSURE SETPOINTS
ECTO
Changes Static Pressure Setpoint
0.02
Unit de-energized during smoke detection. See ECTO
5.01 to operate blower during smoke detection.
0.03
During ventilation
0.04
During heating
0.05
During cooling
TABLE 3
VFD SUPPLY AIR STATIC PRESSURE SETPOINTS
Pressure ”w.c.
DC Voltage
Display Setting
0.00
0.00
0
0.25
0.50
13
0.50
1.00
25
0.75
1.50
38
1.00
2.00
51
1.25
2.50
64
1.50
3.00
77
1.75
3.50
89
2.00
4.00
102
2.25
4.50
115
2.50
5.00
128
2.75
5.50
140
3.00
6.00
153
3.25
6.50
166
3.50
7.00
179
3.75
7.50
191
4.00
8.00
204
4.25
8.50
217
4.50
9.00
230
4.75
9.50
242
5.00
10.00
255
TABLE 4
RECORD ADJUSTED SETPOINTS
ECTO
Setpoint
Description
Setpoint
“w.c.
Display
Setting
0.02
Smoke
0.03
Ventilation
0.04
Heating
0.05
Cooling
B-Unit Operation
Use the Unit Controller to check unit mechanical operation.
See the
Service - Test
section of the Unit Controller manual.
