RTHC-SVN02C-EN
7
Mounting the 4U1 (ASM) Module
UCP2 does not have software capabilities to operate a water regulating valve;
therefore an additional controller is required to monitor the system pressures and
adjust the position of the water valve accordingly. The 4U1 controller is the additional
controller required. It is an adder subtractor module (ASM) manufactured by
Moore
Industries Inc.
and is a special design for Trane. It is not Moore’s standard ASM
module.
On factory installations, the 4U1 controller is mounted on the bracket between the
evaporator and condenser, above the system differential pressure switch.
This module is mounted in a sheet metal box and is labeled “
ASM Adder Subtractor
Module
”. The module will accept the input from two pressure transmitters, one on the
evaporator and one on the condenser. It subtracts the two values to determine the
system differential. The module will then produce either a 4-20 mA or 1-5 VDC signal
output to be wired to the actuator on the water valve.
If the controller is not factory installed, use the procedure below to mount the
controller.
Installation
1.
Locate the factory mounted pressure differential switch for detecting low
system differential. It is located on the left side of the unit while facing the
control panel, between the evaporator and condenser.
2.
Above the switch, mount the 4U1 module to the bracket, facing outward. Use
four 10-32 x 1" screws and four 10-32 nuts.
3.
On the left side of the 4U1 box, press out one of the electrical knock-outs and
install one of the bushing strain reliefs (X1910-0028-350) in the opening.
4.
On the right side of the 4U1 box, press out one of the electrical knock-outs and
install one of the bushing strain reliefs (X1910-0028-350) in the opening. This
should be level with the knock-out on the left side.
5.
On the right side of the 4U1 box, above the strain relief already installed, press
out one of the electrical knock-outs and install the final bushing strain relief
(X1906-0094-010) in the opening.
6.
The module is shipped with a resistor between (+) Out and (-) Out terminals to
supply a 1 to 5 VDC output signal. If a 4-20 mA output signal is required, the
resistor between (+) Out and (-) Out must be removed and discarded.
