Carrier 48DL Installation Manual download pdf (Page 64)

264975-BIM-B-1208

64 Johnson Controls Unitary Products

FLASH CODES

The UCB will initiate a flash code associated with errors

within the system. Refer to UNIT CONTROL BOARD FLASH

CODES Table 80.

RESET

Remove the call for heating by lowering the thermostat set-

ting lower than the conditioned space temperature.This

resets any flash codes.

ELECTRIC HEAT ANTICIPATOR SETPOINTS

It is important that the anticipator setpoint be correct. Too

high of a setting will result in longer heat cycles and a greater

temperature swing in the conditioned space. Reducing the

value below the correct setpoint will give shorter “ON” cycles

and may result in the lowering of the temperature within the

conditioned space. Refer to Table 66 for the required electric

heat anticipator setting.

GAS HEATING SEQUENCE OF OPERATIONS

When the thermostat calls for the first stage of heating, the

low-voltage control circuit from “R” to “W1” is completed. A

call for heat passes through the UCB to the Ignition Control

Board (ICB). The UCB monitors the “W1” call and acts upon

any call for heat by monitoring the Gas Valve (GV). Once

voltage has been sensed at the GV, the UCB will initiate the

fan on delay for heating, energizing the indoor blower the

specified delay has elapsed.

When the thermostat has been satisfied, heating calls are

ceased. The GV is immediately closed. The blower is de-

energized after the fan off delay for heating has elapsed. The

draft motor performs a 30-second post purge.

IGNITION CONTROL BOARD

FIRST STAGE OF HEATING

When the ICB receives a call for first stage of heating, “W1,”

the draft motor is energized. Once the draft motor has been

proven, a 30-second purge is initiated. At the end of the

purge, the GV is opened, and the spark ignitor is energized

for 10 seconds. The ICB then checks for the presence of

flame. If flame is detected, the ICB enters a flame stabiliza-

tion period. If flame was not detected, the GV closes, and a

retry operation begins.

During the flame stabilization period, a loss of the flame for 2

seconds will cause the GV to close and the retry operation to

begin. After the flame stabilization period, a loss of flame for

3/4 second will cause the GV to close and the retry operation

to begin.

At the conclusion of the flame stabilization period, the ICB will

operate the gas heat in high fire for an additional 60 seconds

(for a total for 120 seconds of high fire operation). After this

60 seconds, the ICB will then use the call for the second

stage of heat to control second stage operation of the GV.

When “W1” is satisfied, both valves are closed.

SECOND STAGE OF HEATING

When the ICB receives a call for the second stage of heating,

“W2,” the ICB conducts a complete first stage ignition

sequence. If this sequence is satisfied, the second main

valve of the GV is opened.

When “W2” is satisfied, the second main valve is closed.

RETRY OPERATION

When a flame is lost or is not detected during an attempt to

achieve ignition, a retry operation occurs. A 30-second purge

is performed between ignition attempts.

If the unit fails after three ignition attempts, the furnace is

locked-out for one hour. The furnace is monitored during this

one-hour period for unsafe conditions.

RECYCLE OPERATION

When a flame is lost after the flame stabilization period, a

recycle operation occurs. If the unit fails after five recycle

attempts, the furnace is locked-out for one hour.

GAS HEATING OPERATION ERRORS

LOCK-OUT

A one-hour lockout occurs following three retries or five recy-

cles. During the one-hour lockout, flame detection, limit con-

ditions, and main valves are tested. Any improper results will

cause the appropriate action to occur. Recycling the low volt-

age power cancels the lock-out.

TABLE 65: ELECTRIC HEAT LIMIT SETTING 42”

CABINET

UNIT (TONS) VOLTAGE

HEATER

LIMIT

SWITCH

OPENS °F

DL-07, -08 (7.5, 8.5)

DU-06, -07, -08 (6.5, 7.5, 8.5)

208/230

9135

18 150

24 165

34 190

DL-07, -08(7.5, 8.5)

DU-06, -07, -08 (6.5, 7.5, 8.5)

480

9 135

18 150

24 165

34 185

DL-07, -08 (7.5, 8.5)

DU-06, -07, -08 (6.5, 7.5, 8.5)

600

9 135

18 150

24 150

34 185

TABLE 66: ELECTRIC HEAT ANTICIPATOR

SETPOINTS

SETTING, AMPS

W1 W2

0.13 0.1

1 2 ... 59 60 61 62 63 64 65 66 67 68 69 ... 83 84

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Carrier 48DL Installation Manual Page 64

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