Carrier 48TJD Specifications download pdf (Page 21)

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

24-36 4-20

VDC mA

IN OUT

33CSENTSEN

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

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 55 56

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Carrier 48TJD Specifications Page 21

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