Evaporator Piping Components; Entering Chilled Water Piping; Leaving Chilled Water Piping; Evaporator Drain - Trane RTAA-130 Installation, Operation And Maintenance Manual

RTAA-IOM-3
Evaporator Piping
Components
"Piping components" include all
devices and controls used to provide
proper water system operation and
unit operating safety. These
components and their general
locations are given below.

Entering Chilled Water Piping

[ ] Air vents (to bleed air from system).
[ ] Water pressure gauges with shutoff
valves.
[ ] Vibration eliminators.
[ ] Shutoff (isolation) valves.
Thermometers (if desired).
[ ] Clean-out tees.
[ ] Pipe strainer.
Caution: To prevent tube damage
install strainer in evaporator water
inlet piping.

Leaving Chilled Water Piping

[ ] Air vents (to bleed air from system).
[ ] Water pressure gauges with shutoff
valves. Vibration eliminators.
[ ] Shutoff (isolation) valves.
[ ] Thermometers.
[ ] Clean-out tees.
[ ] Balancing valve.
[ ] Flow Switch (If desired)
Caution: To prevent evaporator
damage, do not exceed 215 psig
(14.6 bar) evaporator water
pressure.

Evaporator Drain

A 3/4" drain connection is located
under the outlet end of the evaporator.
This may be connected to a suitable
drain to permit evaporator drainage
during unit servicing. A shutoff valve
must be installed on the drain line.
42

Evaporator Flow Switch

Chilled water flow protection is
provided by the UCM without the need
for a chilled water flow switch. A flow
switch for chilled water is strictly
discretionary but if not installed, a
signal still must be sent to the chiller to
indicate that water flow has been
established, e.g. chilled water pump
motor starter auxiliary contacts.
If additional chilled water flow
protection is desired, use a field-
installed flow switch or differential
pressure switch with the pump
interlock to sense system water flow.
Install and wire the flow switch in series
with the chilled water pump motor
starter auxiliaries (refer to "Electrical
Wiring").
Specific connection and schematic
wiring diagrams are shipped with the
unit. Some piping and control
schemes, particularly those using a
single water pump for both chilled and
hot water, must be analyzed to
determine how and or if a flow sensing
device will provide desired operation.
Follow the manufacturer's
recommendations for selection and
installation procedures. General
guidelines for flow switch installation
are outlined below
1. Mount the switch upright, with a
minimum of 5 pipe diameters of
straight horizontal run on each side.
Do not install close to elbows,
orifices or valves.
Note: The arrow on the switch must
point in the direction of flow.
2. To prevent switch fluttering, remove
all air from the water system.
Note: The UCM provides a 6-second
time delay after a "loss-of-flow"
diagnostic before shutting the unit
down. Contact a qualified service
representative if nuisance machine
shutdowns persist.