Armstrong World Industries 242 Failed Flame Sense/Trial For Ignition, Low Voltage, “off” delay

SPECIFICATIONS

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8.The 24-volt signal will only be supplied to the limit switch circuit through pin 6 of the 6-pin ignition wire harness and to the pressure switch circuit through pin 2 of the 6-pin ignition wire harness.

9.The system will repeat this sequence until the pressure switch closes and the 24-volt signal is restored at pin 5 of the 6-pin ignition wire harness.

FAILED FLAME SENSE/TRIAL FOR IGNITION

When the pressure switch closes and a 24-volt signal is sent to pin 5 of the 6-pin ignition wire harness, the spark ignition cable terminal and pin 4 of the 6-pin ignition wire harness energize.

1.As spark voltage is supplied to the ignitor elec- trodes, the gas valve opens and this causes the burners to ignite.

2.The ignition control continues to energize spark voltage until a flame sense signal is supplied to the flame terminal on the ignition control.

3.If a flame sense signal is not received at the flame terminal on the ignition control, the spark igni- tion cable terminal remains energized for 10 seconds.

4.After the 10-second trial for ignition, the ignition control de-energizes the spark ignition cable terminal and pin 4 of the 6-pin ignition wire harness. This causes the gas valve to close and the elec- trode spark to stop.

5.Once the 24-volt signal is sent to pin 4 of the 6-pin ignition wire harness, a 30-second circulating air blower “on” delay starts. After the delay is timed out, the circulating air blower starts.

6.After the spark ignition cable terminal de-ener- gizes, the ignition control initiates a 30-second combustion blower inter-purge delay.

7.After 30-second inter-purge, the ignition control energizes the spark ignition cable terminal and pin 4 of the 6-pin ignition wire harness. If the flame sense signal is received at the flame terminal of the ignition control, the unit continues heat call.

8.If the flame sense signal is not received, the system goes through three trials following the above sequence.

9.After three trials, the system goes into lockout and only the high limit switch circuit and pressure switch circuit remain energized during the 60- minute lockout period.

10.If the flame sense is lost during the heat cycle, the gas valve de-energizes immediately and the system goes into the trial sequence.

Magic-Pak: HW/HWC

CALL FOR COOLING

Line Voltage

1.L2 power passes through the fixed closed L2-T2terminals on the contactor to the RUN terminal of the compressor and the COMMON terminal of the capacitor.

2.L1 power is sent to the L1 terminal of the contactor. When the Y signal energizes the contactor, the T2 terminal becomes energized. L1 power is sent to the compressor COMMON terminal and the condenser fan. This energizes the compressor and condenser fan motors.

3.When pin 1 (Y terminal) of the 5-pin thermostat harness receives a 24-volt signal from the thermo- stat, a 5-second circulating air blower delay starts.

4.After the 5-second delay, the ignition control energizes the cooling speed relay. This sends L1 power to the ACB COOL terminal of the ignition control.

5.L1 power is sent to the circulating air blower terminal block, energizing the circulating air blower motor.

6.When the R, Y and G circuit is interrupted by the thermostat, the contactor is immediately de- energized. This interrupts L1 power to the com- pressor and condenser fan motors, stopping both.

7.The ignition control starts a 90-secondcirculat- ing air blower “off” delay, after which the ACB COOL terminal de-energizes. This interrupts L1 power to the circulating air blower motor, causing it to stop.

Low Voltage

1.The thermostat energizes the R, Y and G circuit, sending a 24-volt signal to the contactor coil and to pin 1 of the 5-pin thermostat harness connected to the ignition control.

2.The contactor closes immediately upon receiving the 24-volt signal, causing the compressor and condenser fan motors to start.

3.The 24-volt signal is also sent to pin 1 of the 5-pin thermostat harness, initiating a 5-second circulat- ing air blower “on” delay.

4.After the 5-second delay, the ignition control energizes the cooling speed relay and the circulat- ing air blower starts.

5.When the cooling call is satisfied, the thermostat interrupts the R, Y and G circuit. The contactor de-energizes immediately, causing the compressor and the condenser fan to stop. The ignition control starts a 90-second circulating air blower

“off” delay.

SRM-HW/HWC

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