Carrier JK034-074 Specifications download pdf

Installation Instructions

Part No. 50DJ900021

SAFETY CONSIDERATIONS

Before beginning any modiﬁcation, be certain that the

main line electrical disconnect switch is in the OFF

position. Electric shock could result. Tag disconnect switch

with suitable warning labels.

Installation and servicing of air-conditioning equip-

ment can be hazardous due to system pressure, ﬂammable

gases, and electrical components. Only trained and qualiﬁed

personnel should install, repair, or service air-conditioning

equipment.

Untrained personnel can perform the basic maintenance

functions of cleaning coils and replacing ﬁlters. All other

operations should be performed by trained service person-

nel. When working on air-conditioning equipment, observe

precautions in literature, tags and labels attached to unit, and

other safety precautions that may apply. Follow all safety

codes.

GENERAL

This accessory space temperature reset package consists

of a thermistor and potentiometer. See Table 1. It is used to

elevate the supply-air temperature in 48DK,FK,JK and

50DK,DY,FK,FY,JK,JY variable air volume units in order

to avoid over-cooling of the space while maintaining occu-

pied space air motion and ventilation.

Table 1 — Package Contents

ITEM QUANTITY PART NO.

Thermistor Sensor with

35-ft Leads

1 HH79NZ014

Temperature Reset

Potentiometer

1 32GB500574

INSTALLATION

Thermistor (T10) must be wired in series with poten-

tiometer (P7). The two of them must then be wired to the

appropriate terminal block in the unit control box. All wir-

ing must conform to NEC (National Electrical Code) and

local codes. To install the accessory space temperature reset

package:

1. Turn off all power to unit.

2. Install thermistor T10 in the occupied space to be con-

trolled. Locate the thermistor in the space with the great-

est cooling load, so that the leaving-air temperature is not

reset too much to cool the space with the most demand-

ing cooling load.

3. Mount potentiometer in the unit control box or some other

secure indoor location. Set the potentiometer for the tem-

perature at which reset is to begin. When the occupied

space temperature drops below this setting, reset will

occur.

4. Wire thermistor and potentiometer as shown in Fig. 1.

The thermistor has 35-ft leads, but additional wire may

be spliced in to make the leads longer.

NOTE: When splicing additional wires, solder the wires

at the splices to achieve maximum continuity.

5. Set DIP (dual in-line package) switch no. 2 on the main

VAV (variable air volume) control board to the ON

position to enable the reset function. See Fig. 2.

6. Find potentiometer P3 in the center of the accessory reset

board in the unit control box, and set it for the maximum

reset temperature to be allowed when the unit is in the

Reset mode. See Fig. 3.

7. Multiple T10 space sensors may be used. Multiple (4

or 9) sensors (part no. HH79NZ014) may be wired as

shown in Fig. 4 with total wiring not to exceed 1000 ft.

TB3

TB1

32GB500574

TB2

POTENTIOMETER

THERMISTOR

T10

TB4

TB1

32GB500574

TB2

POTENTIOMETER

THERMISTOR

T10

SIZES 034-048

SIZES 054-074

LEGEND

TB — Terminal Block

Fig. 1 — Accessory Wiring Detail

48/50DK,FK,JK034-074

50DY,FY,JY034-074

Accessory Space Temperature Reset Package

Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations.

Book 1 1

Tab 1a 1b

PC 111 Catalog No. 564-976 Printed in U.S.A. Form 48/50D,F,J-3SI Pg 1 9-98 Replaces: 48/50D-4SI

1 2 3 4

Summary of Contents

Page 1

Installation InstructionsPart No. 50DJ900021SAFETY CONSIDERATIONSBefore beginning any modiﬁcation, be certain that themain line electrical disconnect

Page 2 - VAV — Variable Air Volume

Fig. 2 — Main Variable Air Volume Control BoardLEGENDP—PotentiometerVAV — Variable Air VolumeFig. 3 — Accessory Reset Board2

Page 3 - OPERATION

OPERATIONIf space temperature is equal or less than the reset set point(T10 < P7), the LED (light-emitting diode) 2-digit displayon the unit displa

Page 4 - Tab 1a 1b

Outdoor-Air Temperature Reset — Space tempera-ture is the recommended means of initiating reset because itensures that the space is adequately cooled

Carrier JK034-074 Specifications

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