Supply Air Variable Frequency Drive - Lennox LCH036 Installation Instructions Manual

SUPPLY AIR VARIABLE FREQUENCY DRIVE

OUTDOOR
AIR
SECTION
OPTIONAL
A34
VIEW SHOWN
FROM FRONT
SIDE OF UNIT
FIGURE 33
Pressure Transducer (A30)
The Unit Controller uses input from a pressure transducer
(A30) to maintain a 1.0" w.c. (default) supply duct static
pressure. Refer to the Unit Controller manual ECTO 0.04
and 0.05 to adjust the static pressure setpoint. Press the
Unit Controller menu navigation arrows and select button to
change the setpoint. See Settings - Control - ECTO menu
in the Unit Controller manual.
The pressure transducer is shipped in a box in the blower
compartment on the back side of the unit. Install the
transducer on the supply duct according to manufacturer's
instructions.
Note -Make sure the transducer is installed in the main
supply duct at least 2/3 of the distance away from the unit.
Two twisted pairs of shielded cable must be used to connect
the pressure transducer. See figure 34.
507232-02 9/2015
SUPPLY AIR
VFD (A96)
Page 37
PRESSURE TRANSDUCER WIRING
TWISTED
A30
PAIR
+
NOT
_
CONNECTED
NOT
CONNECTED
+
UNUSED WIRE
FIGURE 34
Excessive Duct Static
The Unit Controller will lock-out the unit for 5 minutes if
supply duct static pressure exceeds 2.0"w.c. (default) for 20
seconds. The Unit Controller will permanently shut down
the unit after three occurrences. See Unit Controller ECTO
5.02, 0.21, and 0.22 to adjust default values.
Optional field-installed high pressure switch (S155) will
de-energize the unit above supply duct static pressure
setpoint. Refer to 3B blower VFD wiring diagram. Set
cut-out pressure at 2"w.c. unless otherwise specified.
Switch must be manually reset.
Supply Air VFD By-Pass Plug (Optional)
The supply air VFD may be by-passed using jack/plug
connections. Locate J/P198 connectors in control box area
under the relays. Disconnect J198 from P198 and connect
J204 to P198. See figure 35. Blower will operate in constant
air volume mode.
SUPPLY AIR VFD BY-PASS CONNECTOR
CONNECTORS USED
FOR SUPPLY AIR
VFD OPERATION
J198
P198
FIGURE 35
UNIT
CONTROLLER
TB18
6
10
DRAIN
TWISTED
PAIR
TB24
1
CONNECTORS USED TO
BY-PASS VFD AND
OPERATE SUPPLY AIR
BLOWER AT MAXIMUM
SPEED
J204
P198