Trane RTAA-100, Installation & Maintenance Manual

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28 RTAA-SVX01A-EN
Installation — Mechanical
CAUTION
Evaporator Damage!
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.
Chilled Water 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 discre-
tionary but if not installed, a signal must be sent to the chiller to indicate that
water flow has been established, eg. chilled water pump motor starter
auxiliary contacts, building automation system, etc.
If additional chilled water flow protection is desired, use a field-installed flow
switch or differential pressure switch with the pump motor starter auxiliary
contacts to sense system water flow. Install and wire the flow switch in
series with the chilled water pump motor starter auxiliaries (refer to
“Interlock 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.
3. Adjust the switch to open when water flow falls below nominal. Evapora-
tor data is shown in
Figure 16 Refer to Table 1 for minimum flow recom-
mendations. Flow switch contacts are closed on proof of water flow.
4. Install a pipe strainer in the entering evaporator water line to protect
components from water-borne debr‘is.