Johnson Controls York VERSECON YSWD 012, Installation Operation & Maintenance

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JOHNSON CONTROLS
FORM 145.05-NOM1 (708)
Compressor Low Pressure (Fault / Alarm)
The control monitors the low pressure input from the
suction pressure transducer for each compressor. Refer
to the “Faults and Alarms” section of this manual for a
description of how the control identifies and responds
to a Compressor Low Pressure situation.
Compressor Low Suction Pressure Control
The control monitors the low-pressure transducer analog
input for each compressor. If the pressure is below 45.0
psig (1.4 Volts DC) for five minutes, it will prevent
the compressor from operating or if the compressor
is operating will turn it off. When the pressure rises
above 48.0 psig (1.48 Volts DC) for ten minutes, the
control will energize the compressor if the demand is
still present.
High Pressure Switch
The high-pressure switch (HP# where # can be A, B,
C, or D depending on the compressor) is located in
the output circuit from the control to the compressor
contactor. The high-pressure switch is a manual reset
single pole pressure activated device that opens on a
pressure rise. When the switch opens, it de-energizes the
compressor circuit shutting down the compressor. The
control is attached to a Schrader fitting on the discharge
line at the compressor. To check the operation of the
pressure switch, shut off water flow to the condenser
and observe the cutout point on a high-pressure gauge.
The switch should open at 410 ±10 psig and close at
300 psig.
Compressor Motor Protector
All 15 horsepower and larger compressors use a solid-
state protection device with sensors embedded in the
windings. The solid-state motor protector (SSM# where
# can be A, B, C, or D depending on the compressor) is
located in the compressor junction box. Whenever the
protection system opens, the compressor is shut down
for a period of 36 minutes.
All 7, 10, and 12 horsepower compressors have in-line
thermal switches embedded in the windings of the
compressor. The control automatically resets when the
thermal switches close. The reset time will vary based
on the ambient temperature.
HEATING OPERATION
The following parameters must be programmed through
the “Setpoints” section of the Keypad / Display or by
a communicated input.
“HEAT- S/A TEMP EN” – The unit can control the
operation of the heating function by either the supply
air temperature or the return air temperature. If supply
air control is desired, this value must be turned ON. ON
is the default value.
“HEAT- S/A TMP SP” – This is the set point the
controller will control to if the unit is configured for
“HEAT-S/A TEMP EN” . The default value is 110.0°
F.
“HEAT- R/A TMP EN” – The unit can control the
operation of the heating function by either the supply
air temperature or the return air temperature or both. If
return air control is desired, this value must be turned
ON. ON is the default value.
It is strongly recommended that both
supply air and return air be used for
all heating applications.
In order to prevent simultaneous
operation of the heating and cooling
functions, the “COOL-R/A TMP SP”
should be set at least 3.0 °F above the
“HEAT-R/A TMP SP”.
“HEAT- R/A TMP SP” – This is the set point the
controller will control to if the unit is configured for
“HEAT- R/A TEMP EN”
. The default value is 72.0°
F.
Sequence of Operation
There is a one minute delay from the time the air
proving switch closes until the heating sequence can
be initiated.
Supply Air Temperature Control
There is a one minute delay from the time the air-
proving switch closes until heating operation is allowed.
Heating operation will be enabled when the supply air
temperature is 5.0° F less than the “HEAT- S/A TMP
SP” set point. Heating operation will be disabled
when the supply air temperature is 2.0° F greater than
the
“HEAT- S/A TMP SP”
set point. The control waits
one minute from the time the supply air temperature
increases 2.0° F above the set point before it disables
the Heating operation.
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