Figure 1. Flow Switch Installation; Flow-Sensing Devices - Trane CVHE Installation Manual

Required Flow-Sensing
Devices
Use either flow switches or
differential pressure switches in
conjunction with the pump interlocks
to verify evaporator and condenser
water flows.
To assure adequate chiller
protection, wire the chilled-water
and condenser-water flow switches
in series with the appropriate water
pump interlock. Refer to the wiring
diagrams that shipped with the unit
for specific electrical connections.
Unless stated otherwise, all flow
sensing devices must be field
supplied. Be sure to follow the
manufacturer's recommendations
for device selection and installation.

Figure 1. Flow switch installation

6
Water Piping
Also, review the general flow switch
installation guidelines listed below.
1. Mount the flow switch upright in
horizontal section of pipe. Allow at
least five pipe diameters of
straight, horizontal run on each
side of the switch.
2. To assure that the flow switch
operates as designed, adjust the
length of the flow switch paddle to
compensate for the pipe diameter
and the height of the coupling tee
used to install the switch.
3. Install the flow switch using a
coupling that is large enough to
allow the insertion of a bushing
one pipe diameter larger than the
flow switch base (Figure 1). This
will prevent interference with the
flow switch paddle.
4. Verify that the direction-of-flow
arrow on the switch points in the
same direction as actual water
flow through the piping circuit.
5. Remove all air from the piping
circuit to prevent possible flow
switch "fluttering."
6. Adjust the flow switch to open
when water flow is less than
normal.
CAUTION
Proof of Flow Switch!
Evaporator and condenser water
circuits require proof of flow
switches. Failure to provide flow
switches or jumping-out of switches
may result in severe equipment
damage.
Evaporator and condenser "proof of
flow" switches (either flow or Delta-
P) are required in series with the
pump contactor auxiliary shown on
wiring diagrams. These switches are
used with control logic to confirm
flow prior to starting a unit and to
stop a running unit if flow is lost. For
trouble shooting, a viewable
diagnostic is generated if a "proof of
flow" switch does not close when
flow is required. Failure to include
the condenser "proof of flow" switch
and "jumping out" this switch could
cause the unit to stop on a
secondary level of protection such as
high condenser pressure. Frequent
cycling on these higher level
diagnostic devices could cause
excessive thermal and pressure
cycling of unit components (O-rings,
gaskets, sensors, motors, controls,
etc.) resulting in premature failure.
CVHE-SVN02D-EN