Evaporator Pump Control And York Hydro Kit Pump Control - York YCAL0019 Installation, Operation And Maintenance Manual

FORM 150.67-NM1
ISSUE DATE: 4/28/2017
start simultaneously. The anti-coincidence timer as-
sures there is at least a one minute delay between sys-
tem starts on 2-circuit systems. This timer is NOT pro-
grammable. The load timers further assure that there
is a minimum time between compressor starts within
a system.
EVAPORATOR PUMP CONTROL AND YORK
HYDRO KIT PUMP CONTROL
The evaporator pump dry contacts (CTB2 – terminals
23 and 24) are energized when any of the following
conditions are true:
1. Low Leaving Chilled Liquid Fault.
2. Any compressor is running.
3. Daily Schedule is ON, Unit Switch is ON and Re-
mote Stop is closed.
The pump will not run if the micro panel has been pow-
ered up for less than 30 seconds or if the pump has run in
the last 30 seconds to prevent pump motor overheating.
Whenever the option "YORK HYDRO KIT PUMPS =
1" is selected under the OPTIONS key, the pump con-
trol will be as described above. DO NOT SELECT the
option "YORK HYDRO KIT PUMPS = 2" under the
OPTIONS key. If a dual pump option is installed, the
active pump is selected by the selector switch.
EVAPORATOR HEATER CONTROL
The evaporator heater is controlled by ambient air tem-
perature. When the ambient temperature drops below
40 °F (4.4 °C) the heater is turned ON. When the tem-
perature rises above 45 °F (7.2 °C) the heater is turned
OFF. An under voltage condition will keep the heater
OFF until full voltage is restored to the system.
PUMPDOWN CONTROL
Each system has a pump-down feature upon shut-off.
Manual pumpdown from the keypad is not possible. On
a non-safety, non-unit switch shutdown, all compres-
sors but one in the system will be shut OFF. The LLSV
will also be turned OFF. The final compressor will be
allowed to run until the suction pressure falls below the
cutout, or for 180 seconds, whichever comes first.
JOHNSON CONTROLS
STANDARD CONDENSER FAN CONTROL
Condenser fan operation must be programmed with the
OPTIONS key under "Fan Control." Condenser fan
control can be selected for Ambient Temperature and
Discharge Pressure, or Discharge Pressure only.
The condenser fan control by "Ambient Temperature
and Discharge Pressure" is a feature that is integral to
the standard software control. If the optional discharge
transducer is not installed, the condenser fans will op-
erate based on outdoor ambient temperature only. Re-
fer to the following pages for model specific details.
The condenser fan control by "Discharge Pressure" is
a feature that can be selected if the discharge pressure
transducer is installed and fan cycling is not a concern.
Fan control by discharge pressure will work according
to the tables on the following pages. The fan control
on-pressure and fan differential off-pressure are pro-
grammable under the PROGRAM key.
The delay between turning ON and OFF fan stages is
always fixed at 5 seconds.
When a fan stage is turned ON by pressure, the on
pressure for the next stage is increased 20 PSIG and
ramped back to the programmed on pressure over the
next 20 seconds. Typically, standard ambient control
on pressure should be programmed at 385 PSIG with a
differential of 125 PSIG.
When a fan stage is turned OFF (programmed on pres-
sure minus programmed differential), the off pressure
for the next stage is decreased 20 PSIG and ramped
back to the programmed off pressure minus the differ-
ential over the next 20 seconds.
A low ambient kit MUST be installed
when "AMBIENT CONTROL LOW
AMBIENT" is selected under the OP-
TIONS key.
Compressor damage could occur if
programming does not match installed
hardware.
Detailed Standard Fan Control operation is shown in
Table 20 and 21.
SECTION 8 – UNIT OPERATION
187
8