Differential Enthalpy Control; Enthalpy Sensors And Control - Carrier 50HJQ014 Installation, Start-Up And Service Instructions Manual

DIFFERENTIAL ENTHALPY CONTROL (Fig. 25) —
Differential enthalpy control requires both an enthalpy switch/
receiver (33CSENTHSW)
(33CSENTSEN). The enthalpy switch/receiver is mounted in
the outdoor air inlet and calculates outdoor air enthalpy. The
enthalpy sensor is mounted in the return airstream and calcu-
lates the enthalpy of the indoor air.
The enthalpy switch/receiver energizes the HI Enthalpy re-
lay output when the outdoor enthalpy is greater than the indoor
enthalpy. The LOW Enthalpy terminal is energized when the
outdoor enthalpy is lower than the indoor enthalpy. The relay
output is wired to the unit economizer which will open or close
depending on the output of the switch.
NOTE: The enthalpy calculation is done using an average alti-
tude of 1000 ft above sea level.
Mounting — Mount the enthalpy switch/receiver in a location
where the outdoor air can be sampled (such as the outdoor air
intake). The enthalpy switch/receiver is not a NEMA 4 enclo-
sure and should be mounted in a location that is not exposed to
outdoor elements such as rain, snow, or direct sunlight. Use
two field-supplied no. 8 x 3 / -in. TEK screws. Insert the screws
4
through the holes in the sides of the enthalpy switch/receiver.
Mount the enthalpy sensor in a location where the indoor air
can be sampled (such as the return air duct). The enthalpy
sensor is not a NEMA 4 enclosure and should be mounted in a
location that is not exposed to outdoor elements such as rain or
snow. Use two field-supplied no. 8 x
the screws through the holes in the sides of the enthalpy sensor.
Wiring — Carrier recommends the use of 18 to 22 AWG
twisted pair or shielded cable for all wiring. All connections
1
must be made with / -in. female spade connectors.
4
The PremierLink™ board provides 24-vac to power the en-
thalpy switch/receiver. Connect the GND and 24 VAC termi-
nals on the enthalpy switch/receiver to the terminals on the
transformer. On some applications, the power from the econo-
mizer harness can be used to power the enthalpy switch/receiv-
er. To power the enthalpy switch/receiver from the economizer
harness, connect power of the enthalpy switch/receiver to the
red and brown wires (1 and 4) on the economizer harness.
Connect the LOW Enthalpy terminal on the enthalpy
switch/receiver to J4 — pin 2 of the PremierLink control on the
HVAC unit. The switch can be powered through the Premier-
Link control board if desired. Wire the 24 VAC terminal on the
enthalpy switch/receiver to J4 — pin 1 on the PremierLink
control. Wire the GND terminal on the enthalpy switch/
receiver to J1 — pin 2 on the PremierLink control. The HI
Enthalpy terminal is not used. See Fig. 24.
Connect the 4-20 mA IN terminal on the enthalpy switch/
receiver to the 4-20 mA OUT terminal on the return air en-
thalpy sensor. Connect the 24-36 VDC OUT terminal on the
enthalpy switch/receiver to the 24-36 VDC IN terminal on the
return air enthalpy sensor. See Fig. 25.
Enthalpy Switch/Receiver Jumper Settings — There are two
jumpers. One jumper determines the mode of the enthalpy
switch/receiver. The other jumper is not used. To access the
jumpers, remove the 4 screws holding the cover on the
enthalpy switch/receiver and then remove the cover. The fac-
tory settings for the jumpers are M1 and OFF.
The mode jumper should be set to M2 for differential en-
thalpy control. The factory test jumper should remain on OFF
or the enthalpy switch/receiver will not calculate enthalpy.
Enthalpy Sensor Jumper Settings — There are two jumpers.
One jumper determines the mode of the enthalpy sensor. The
other jumper is not used. To access the jumpers, remove the
and an enthalpy sensor
3 / -in. TEK screws. Insert
4
4 screws holding the cover on the enthalpy sensor and then re-
move the cover. The factory settings for the jumpers are M3
and OFF.
The mode jumper should be set to M3 for 4 to 20 mA
output. The factory test jumper should remain on OFF or the
enthalpy sensor will not calculate enthalpy.
ENTHALPY SENSORS AND CONTROL — The enthalpy
control (HH57AC077) is supplied as a field-installed accessory
to be used with the EconoMi$er2 damper control option. The
outdoor air enthalpy sensor is part of the enthalpy control. The
separate field-installed accessory return air enthalpy sensor
(HH57AC078) is required for differential enthalpy control.
NOTE: The enthalpy control must be set to the "D" setting for
differential enthalpy control to work properly.
The enthalpy control receives the indoor and return
enthalpy from the outdoor and return air enthalpy sensors and
provides a dry contact switch input to the PremierLink™
controller. Locate the controller in place of an existing econo-
mizer controller or near the actuator. The mounting plate may
not be needed if existing bracket is used.
A closed contact indicates that outside air is preferred to the
return air. An open contact indicates that the economizer
should remain at minimum position.
Outdoor Air Enthalpy
(HH57AC077) — To wire the outdoor air enthalpy sensor,
perform the following (see Fig. 26 and 27):
NOTE: The outdoor air sensor can be removed from the back
of the enthalpy controller and mounted remotely.
1. Use a 4-conductor, 18 or 20 AWG cable to connect the
enthalpy control to the PremierLink controller and power
transformer.
2. Connect the following 4 wires from the wire harness
located in rooftop unit to the enthalpy controller:
a. Connect the BRN wire to the 24 vac terminal (TR1)
on enthalpy control and to pin 1 on 12-pin harness.
b. Connect the RED wire to the 24 vac GND terminal
(TR) on enthalpy sensor and to pin 4 on 12-pin
harness.
c. Connect the GRAY/ORN wire to J4-2 on Premier-
Link controller and to terminal (3) on enthalpy
sensor.
d. Connect the GRAY/RED wire to J4-1 on Premier-
Link controller and to terminal (2) on enthalpy sensor.
NOTE: If installing in a Carrier rooftop, use the two gray wires
provided from the control section to the economizer to connect
PremierLink controller to terminals 2 and 3 on enthalpy sensor.
Return Air Enthalpy Sensor — Mount the return-air enthalpy
sensor (HH57AC078) in the return-air duct. The return air
sensor is wired to the enthalpy controller (HH57AC077). The
outdoor enthalpy changeover set point is set at the controller.
To wire the return air enthalpy sensor, perform the follow-
ing (see Fig. 26):
1. Use a 2-conductor, 18 or 20 AWG, twisted pair cable to
connect the return air enthalpy sensor to the enthalpy
controller.
2. At the enthalpy control remove the factory-installed
resistor from the (SR) and (+) terminals.
3. Connect the field-supplied RED wire to (+) spade
connector on the return air enthalpy sensor and the (SR+)
terminal on the enthalpy controller. Connect the BLK
wire to (S) spade connector on the return air enthalpy
sensor and the (SR) terminal on the enthalpy controller.
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Sensor/Enthalpy Controller