Issue:
Are flow switches required for both the evaporator and condenser water loops?
Resolution:
RTHD Chillers: Flow Sensing Devices
The installer must provide flow switches or differential pressure switches with pump interlocks to sense system water flow. Flow switch locations are schematically shown in Figure 15. To provide chiller protection, install and wire flow switches in series with the water pump interlocks, for both chilled water and condenser water circuits (refer to the Installation Electrical section). Specific connections and schematic wiring diagrams are shipped with the unit.
Flow switches must stop or prevent compressor operation if either system water flow drops off below the required minimum shown on the pressure drop curves. Follow the manufacturers recommendations for selection and installation procedures. General guidelines for flow switch installation are outlined below.
Mount the switch upright, with a minimum of 5 pipe diameters 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 the water flow.
To prevent switch fluttering, remove all air from the water system
NOTE: The CH530 provides a 6-second time delay on the flow switch input before shutting down the unit on a loss-of-flow diagnostic. Contact a qualified service organization if nuisance machine shutdowns persist.
Adjust the switch to open when water flow falls below nominal. Refer to the General Data table in Section 1 for minimum flow recommendations for specific water pass arrangements. Flow switch contacts are closed on proof of water flow.
Evaporator
- The evaporator requires a flow proving device (flow switch or DP switch) AND pump AUX contacts for flow verification.
- Translated...flow proving on the evaporator requires both types of flow proving tied in series on the flow switch input.
Condenser
- The condenser requires a flow proving device (flow switch or DP switch) AND/OR pump AUX contacts for flow verification.
- Translated...flow proving on the condenser requires one or the other, or both types of flow proving tied in series on the flow switch input.
Notes:
In December of 2009, Trane-Pueblo introduced an optional factory installed IFM efector flow switch on the RTWD chiller.
Changes:
Other Question/Problem/Cause Statements:
- Are flow switches required for both the evaporator and condenser water loops?
- Condenser Flow Proving?
- Evaporator Flow Proving?
- Condenser Flow Switch?
- Evaporator Flow Switch?
Facts:
- Water-Cooled Chiller (Pueblo) (RTHD)
- Water-Cooled Chiller (Pueblo) (RTWD)
Document Identifier: DOC-80507
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.