Power Exhaust - York J ZJ Series Instruction Manual

5803641-JIM-B-0620
In free cooling, with a thermostat input to Y1, the dampers
modulate to control the supply air temperature to the
Economizer Setpoint +/- 1°F (default 55°F).
If the thermostat provides an input to Y2 and the parameter
Compressors Off in Free Cooling is turned OFF a compressor
output energizes. The economizer dampers continue to
modulate to control the supply air temperature to the
Economizer Setpoint.
If the supply air temperature cannot be maintained within 5°F of
the economizer setpoint, the first stage compressor (C1) will be
turned on. Second stage compressor (C2) will be added as
needed to keep the supply air temperature within the 5°F of the
economizer setpoint.
Sensor
In free cooling, with a demand from the zone/return sensor for
the first stage of cooling, the dampers modulate to control the
supply air temperature to the Economizer Setpoint +/- 1°F.
If the economizer output is at 100% and the SAT is greater than
the Economizer setpoint + 1°F, the control starts a 12-minute
timer to energize a compressor output.
If at any time the economizer output drops below 100% the
timer stops and resets when the economizer output returns to
100%.
Once a compressor output is turned ON, the economizer
dampers continue to modulate to control the supply air
temperature to the Economizer Setpoint.
At no time will a compressor output be turned ON if the
economizer output is less than 100%, even if the differential
between zone (or return) temperature and the current cooling
setpoint is great enough to demand more than one stage of
cooling.
If the economizer output goes to minimum position and the SAT
is less than Economizer Setpoint -1°F, the control starts a 12-
minute timer to de-energize a compressor output.
30
If at any time the economizer output goes above the minimum
position the timer stops and resets when the economizer output
returns to minimum position.
If the demand for cooling from the space/return is satisfied, the
economizer output will modulate to minimum position and the
compressor outputs will be de-energized as long as their
minimum run timers have expired.

Power Exhaust

Setpoints
a. Economizer Enable
b. Power Exhaust Enable
c. Modulating Power Exhaust
d. Exhaust VFD Installed
e. Building Pressure Sensor Enabled
f. Econo Damper Position For Exh Fan
g. Econo Damper Position For Exh Fan OFF Percent
Inputs
No inputs are present for non-modulating power exhaust.
Outputs
a. 2-10 VDC from ECON on Economizer Expansion module
b. 24 VAC from EX-FAN to energize exhaust fan on
Economizer Expansion module
Operation
Operation details include:
a. Compares economizer output to the Economizer Damper
Position For Exhaust Fan On and OFF.
b. Energizes exhaust fan when economizer output is above
Economizer Damper Position For Exhaust Fan On.
c. De-energizes exhaust fan when economizer output is
below the Economizer Damper Position for Exhaust Fan
OFF
ON
ON
OFF
OFF
OFF
ON Percent
Johnson Controls Ducted Systems