RT-SVX23D-EN 7
General Information
RTOM – ReliaTel™ Options Module (Optional)
The RTOM monitors the supply fan proving, clogged filter, supply air temperature, exhaust fan
setpoint, supply air tempering, Frostat™ and smoke detector. Refer to system input devices and
functions for operation.
System Input Devices & Functions
The RTRM must have a zone sensor or thermostat input in order to operate the rooftop unit. The
flexibility of having several mode capabilities depends upon the type of zone sensor thermostat
selected to interface with the RTRM.
The descriptions of the following basic Input Devices used within the RTRM network are to acquaint
the operator with their function as they interface with the various modules. Refer to the unit’s
electrical schematic for the specific module connections.
The following controls are available from the factory for field installation.
Supply Fan Failure Input (Optional)
The Fan Failure Switch can be connected to sense indoor fan operation:
FFS (Fan Failure Switch) If air flow through the unit is not proven by the differential pressure switch
connected to the RTRM (factory set point 0.07 “ w.c.) within 40 seconds nominally, the RTRM will
shut off all mechanical operations, lock the system out, send a diagnostic to ICS, and the SERVICE
output will flash. The system will remain locked out until a reset is initiated either manually or
through ICS.
Clogged Filter Switch (Optional)
The unit mounted clogged filter switch monitors the pressure differential across the return air
filters. It is mounted in the filter section and is connected to the RTOM. A diagnostic SERVICE signal
is sent to the remote panel if the pressure differential across the filters is at least 0.5" w.c. The
contacts will automatically open when the pressure differential across the filters decreases to
approximately 0.4" w.c. The clogged filter output is energized when the supply fan is operating and
the clogged filter switch has been closed for at least 2 minutes. The system will continue to operate
regardless of the status of the filter switch.
Note: On units equiped with factory installed MERV 13 filters, a clogged filter switch with different
pressure settings will be installed. This switch will close when the differential pressure is
approximately 0.8' w.c. and open when the differential falls to 0.7" w.c.
Compressor Disable (CPR1/2)
This input incorporates the low pressure control (LPC) of each refrigeration circuit and can be
activated by opening a field supplied contact installed on the LTB.
If this circuit is open before the compressor is started, the compressor will not be allowed to
operate. Anytime this circuit is opened for 1 continuous second during compressor operation, the
compressor for that circuit is immediately turned “Off”. The compressor will not be allowed to
restart for a minimum of 3 minutes should the contacts close.
If four consecutive open conditions occur during the first three minutes of operation, the
compressor for that circuit will be locked out, a diagnostic communicated to the remote panel (if
installed), and a manual reset will be required to restart the compressor.
Low Pressure Control
When the LPC is opened for 1 continuous second, the compressor for that circuit is turned off
immediately. The compressor will not be allowed to restart for a minimum of 3 minutes.
If four consecutive open conditions occur during an active call for cooling, the compressor will be
locked out, a diganostic communicated to ICS™, if applicable, and a manual reset required to
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