Specifications

Loop Pump Circuit Breakers
(Single Compressor Units)
The loop pump(s) and desuperheater pump
are protected by control box mounted circuit
breakers for easy wiring of pumps during
installation. Circuit breakers eliminate the need
to replace fuses.
Safety Controls
The control receives separate signals for
high pressure, low pressure, low water ow,
and condensate overow faults. Upon a
continuous 30-second measurement of the
fault (immediate for high pressure), compressor
operation is suspended (see Fault Retry below),
and the appropriate LED ashes. Once the unit
is locked out (see Fault Retry below), an output
(terminal “L”) is made available to a fault LED
at the thermostat (water-to-water unit has fault
LED on the corner post).
Low Pressure: If the low pressure switch is open
for 30 continuous seconds, the compressor
operation will be interrupted, and the control
will go into fault retry mode. At startup, the low
pressure switch is not monitored for 90 seconds
to avoid nuisance faults.
High Pressure: If the high pressure switch
opens, the compressor operation will be
interrupted, and the control will go into fault
retry mode. There is no delay from the time the
switch opens and the board goes into fault
retry mode. There is also no delay of switch
monitoring at startup.
Flow Switch: If the ow switch is open for 30
continuous seconds, the compressor operation
will be interrupted, and the control will go into
fault retry mode. At startup, the ow switch
is not monitored for 30 seconds to avoid
nuisance faults.
Condensate Overow: If water touches the
condensate overow sensor for 30 continuous
seconds, the compressor operation will be
interrupted, and the control will go into
fault retry mode. There is no delay of switch
monitoring at startup.
FAULT RETRY
All faults are retried twice before nally locking
the unit out. The fault retry feature is designed to
prevent nuisance service calls. There is an anti-
short cycle period between fault retries. On the
third fault, the board will go into lockout mode.
Over/Under Voltage Shutdown
The lockout board protects the compressor
from operating when an over/under voltage
condition exists. The control monitors secondary
voltage (24VAC) to determine if an over/
under voltage condition is occurring on the
primary side of the transformer. For example, if
the secondary voltage is 19 VAC, the primary
voltage for a 240V unit would be approximately
190V, which is below the minimum voltage
(197V) recommended by the compressor
manufacturer. This feature is self-resetting. If
the voltage comes back within range, normal
operation is restored. Therefore, over/under
voltage is not a lockout.
Under voltage (18 VAC) causes the compressor
to disengage and restart when the voltage
returns to 20 VAC. Over voltage (31 VAC)
causes the compressor to disengage and
restart when the voltage returns to 29 VAC.
During an over or under voltage condition,
all ve fault LEDs will blink (HP + LP + FS + CO
+ Status). When voltage returns to normal
operation, the four fault LED’s will stop blinking,
but the status LED will continue to ash. While
the board LEDs are ashing, the thermostat
fault light will be illuminated.
O/B Y1 G W1 R ODD W2 Y2 C
W1
COM
24VAC
COM2
XFMR
SEC
CFM
ECM
Board
ECM Board Layout
20
Roth RXT Series Catalog - August 2010
Controls