(10B): 2-Pipe Mode - Lutron Electronics PALLADIOM Configuration Manual

Step 4: Set the SMC55-HWQS Basic Parameters for System
Compatibility
(continued)

(10b): 2-Pipe Mode

Applicable System: 2-pipe Fan Coil Units.
Use this parameter to select the type of 2-pipe mode. Heat only mode is used only for heating, Cool only mode is used only
for cooling. Changeover mode is used to either heat or cool depending on the temperature of the water in the pipes. In the
changeover mode, a changeover sensor must be connected to the SMC55-HWQS. Refer to the Thermostat installation guide to
install the changeover sensor.
When the water temperature is above the value selected for the advanced parameter 'ChangeOverToHeatTemperature',
the SMC55-HWQS switches to the heating mode. It stays in the heating mode until the water temperature falls below the
value selected for the advanced parameter 'ChangeOverToCoolTemperature'. When the water temperature is below the
value selected for the advanced parameter 'ChangeOverToCoolTemperature', the SMC55-HWQS changes over to cooling
mode. It stays in the cooling mode until the water temperature rises above the value selected for the advanced parameter
'ChangeOverToHeatTemperature'.
If the water temperature is between the two changeover points immediately after power up, the operating mode starts in the
previous mode as per the value in the advanced parameter '2PipePreviousOperatingMode'. The water temperature is measured
at 30 second intervals and the operating mode is updated accordingly.
This parameter will be skipped in the menu if you select any option other than 02: 2-Pipe for the previous parameter (01b). Refer
to HVAC equipment manual to identify the type of 2-pipe FCU. The different options available for this parameter are listed in the
table below:
Table 13: Values for 2-pipe Mode
2-Pipe Mode (10b) Default Value
01: Heat only
02: Cool only 03: Changeover
03: Changeover
Continued on next page...
15
P/N 032498h