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DIFFERENTIAL ENTHALPY CONTROL (Fig. 29) --
Diffemntifd enthalpy control mquiles both fin enthalpy switch/
receiver (33CSENTHSW) and fin enthalpy sensor
(33CSENTSEN). The enthalpy switchkeceiver is mounted in
the outdoor air inlet and calculates outdoor air enthalpy. Tile
enthalpy sensor is mounted in the return airstream and cfflcu-
lates the enthalpy of the indoor all:
The enthalpy switclffleceiver energizes the HI Enthalpy re-
lay output when the outdoor enthalpy is greater than file 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 fl 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 fred should be mounted in a location that is not exposed to
outdoor elements such as rain, snow. or dilect sunlight. Use
two field-supplied no. 8 x 3/4-in. TEK screws. Insert the screws
through the holes in the sides of the enthalpy switclffreceivel:
Mount the enthalpy sensor in a location whele the indoor air
can be smnpled (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 3/4-in. TEK screws. Insert
the screws through the holes in the sides of the enthalpy sensol:
Wiring -- Carrier recommends the use of 18 to 22 AWG
twisted pair or shielded cable for all wiring. All connections
must be made with I/4-in. female spade connectors.
The PlemierLink TM board provides 24-vac to power the
enthfflpy switch/receivel: Connect the GND and 24 VAC termi-
nals on the enthfflpy switch/receiver to the terminals on
the transformer On some applications, the power from the
economizer hmness can be used to power the enthalpy switch/
leceivel: To power the enthalpy switchkeceiver from the
economizer harness, connect power of the enthalpy switch/
receiver to the led and brown wires (1 and 4) on the econo-
mizer harness.
Connect the LOW Enthalpy terminal on the enthalpy
switch/receiver to J4 -- pin 2 of the PlemierLink control on the
HVAC unit. The switch can be powered through the Premier-
Link control board if desired. Wire file 24VAC terminal on the
enthalpy switclffreceiver to J4 -- pin 1 on the PremierLink
control. Wire the GND terminal on the enthalpy switch/
receiver to Jl -- pin 2 on the PremierLink control. The HI
Enthalpy terminal is not used. See Fig. 28.
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 terminfd on the
enthalpy switch/leceiver to the 24-36 VDC IN terminal on the
return air enthalpy sensor. See Fig. 29.
Enthalpy Switch/Receiver Jumper Settings -- There are two
jumpers. One jumper determines the mode of the enthalpy
switch/receivel: The other jumper is not used. To access the
jumpers, lemove the 4 screws holding the cover on the
enthalpy switclffreceiver find then remove the covel: The fac-
tory settings for the jumpers me M I and OFE
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.
120 VAC
LINE VOLTAGE
_jk.jM.Z.__/
]
24 VAC OUTPUT FROM N/C CONTACT WHEN THE
OUTDOOR ENTHALPY IS LESS THAN THE f
INDOOR ENTHALPY ,i ORN
24 VAC OUTPUT FROM N/O CONTACT WHEN THE 4--
INDOOR ENTHALPY IS GREATER THAN THE
OUTDOOR ENTHALPY
HI LOW GND 24
ENTHALPY VAC
33CSENTHSW
4-20 24-36
mA VDC
IN OUT
f
j!
/
24-36 4-20
VDC mA
IN OUT
33CSENTSEN
J
LEGEND
N/C -- Normally Closed
N/O -- Normally Open
JUMPER SETTINGS FOR 33CSENTHSW JUMPER SETTINGS FOR 33CSENTSEN
O o on
[l°°°l
O0 000
Fig. 29 -- Differential Enthalpy Control Wiring
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