Armstrong World Industries 182, 243, 302, 242, 122, 123, 203, 183 manual Power

SPECIFICATIONS Magic-Pak: HW/HWC

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Detailed Sequence - HWC122, 182, 242, 302 (w/Fenwal 05-29 Ignition Control)

Refer to Figure 2-5

POWER

Line Voltage

When the service disconnect switch is closed, power is sent to the unit (unit in standby, no signal from the thermostat). Power (208 - 230 volts A/C) is supplied to both black wires located in the junction block on top of the unit.

Line voltage will be present at the following locations:

First black wire

1.L-1 on the ignition module

2.L-1 on the contactor

3.L-1 on the blower control board

4.Terminal on the transformer marked 208V or 240V (whichever is being used)

Second black wire

1.Supplies power to the induced draft blower

2.L-2 on the contactor

3.Common terminal on the transformer

4.T-2 on the contactor

5.Red wire on the R terminal of the compressor

6.Red wire to the common terminals on the capaci- tors

Low Voltage (24 VAC)

With the unit at rest (no call from the thermostat), 24 volts A/C will be found at these points:

1.Red wire exiting the top of the unit

2.Terminal marked 24VAC on the ignition control

3.Terminal R on the blower control board

CALL FOR HEAT

Line Voltage

The thermostat closes the circuit between R and W.

The following is the sequence of operation for the line voltage side of the unit:

1.Terminal TS (24-volt) energizes on the ignition control, causing a relay in the ignition control to close. This sends line voltage to the terminal marked IND, causing the induced draft blower to start.

2.When W is energized, a 24-volt signal is also sent to the W terminal on the blower control board. The 24-volt signal starts the timer on the blower con- trol board. After 60 seconds, the heat speed relay on the blower control board closes. This sends line voltage from the terminal marked HEAT to the circulating air blower, starting the blower. The induced draft blower and the circulating air blower continue to operate until the heat call is satisfied, interrupting the circuit between R and W. The W terminal de-energizes, causing the blower relay to open approximately 90 seconds later. This interrupts the line voltage to the circulating air blower and the blower shuts down.

Low Voltage

1.A call for heat closes the circuit in the thermostat between R and W, sending a 24-volt signal to the white wire on the unit.

2.The white wire goes to the C terminal on the limit switch, ignition control terminal TS and terminal W on the blower control board.

3.When W energizes, the timer starts a countdown to circulating air blower “on”. The blower starts in approximately 60 seconds.

4.The 24-volt signal sent to the TS terminal closes a relay in the ignition control. This starts the induced draft blower by energizing terminal IND on the ignition control.

5.As the induced draft blower comes up to speed and creates enough negative pressure, the pres- sure switch closes. The 24-volt signal is sent from the pressure switch to one side of the Normally Closed manual reset rollout switch. If the rollout switch is closed, the 24-volt signal is passed through the switch to the P.SW terminal on the ignition control. This initiates a 30-second pre- purge period.

6.After the 30-second pre-purge period, a trial for ignition starts by energizing the spark terminal and the V1 terminal simultaneously. The 24-volt signal from V1 energizes the gas valve solenoid, causing it to open. These actions cause the burners to light.

7.After the burners are lit, a flame sense is picked up by the flame sense rod located at the opposite end of the burner rack from the spark electrodes. The flame sense signal is sent to the S1 terminal of the ignition control. The unit continues to operate as long as W is energized.

8.When the call for heat is satisfied, the circuit be- tween R and W is interrupted, de-energizing W.

SRM-HW/HWC

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