Operating Sequence, Standing Pilot | Nordyne SERIES M1B, AND M5S

OPERATING SEQUENCE

Standing Pilot

1 On a call for heat, the thermostat contacts close, supplying 24VAC to the gas valve.When energized, the valve steps open at a reduced

ﬂ ow and opens fully within 14 seconds.

2.When the call for heat is satisfied, the thermostat contacts open, shutting off gas ﬂow.

Standing Pilot w/Induced Draft Blowers

1.On a call for heat, the thermostat contacts close, supplying 24 VAC to the relay.

2.The relay contacts close and the induced draft motor energizes.

3.When the inducer starts, the air pressure switch closes at -0.20W.C.differential pressure and energizes the gas valve. The valve steps open at a reduced ﬂ ow and opens fully after approximately 14 seconds.

4.When the call for heat is satisfied, the thermostat contacts open, the gas valve shuts off gas ﬂow, and the induced draft blower stops.

M1M Models with Direct Ignition

1.On a call for heat, the thermostat contacts close, supplying 24 VAC between terminals C and W of the control module.

2.When the inducer starts, the air pressure switch closes at -0.20 W.C. differential pressure and energizes the gas valve.

3.After a 45 second purge, the ignitor is energized for a 30 second warm-up period. After warm up, the gas valve opens. NOTE: The time for ignition is approximately 6 seconds, after which

the gas valve either remains open if ﬂ ame is sensed, or closes if ﬂ ame is not sensed.

5.If ﬂ ame is not sensed, the sequence repeats four more times before a lockout occurs. To reset, wait 30 seconds and then interrupt the

24VAC power by turning the room thermostat below room temperature, then returning it to the original set point.

6.If ﬂ ame does not establish on the 5th attempt (initial ﬁre + 4 re-tries), the control de-energizes the gas valve, the red LED ﬂ ashes 4 times, and the furnace locks out heat operation for

1hour. See Table 9 (page 29).

7.If a ﬂ ame is present, the control energizes the main blower on heat speed 30 seconds after the gas valve opens.

8.When call for heat is satisﬁ ed the thermostat contacts open, the gas valve shuts off gas ﬂ ow and the combustion blower remains on for a

30second post-purge period.

9.The main blower is de-energized after a 120 second blower off delay.

Oil Gun Furnace with Honeywell R7184 / Beckett 7505 Control - M5S Models

1.When a call for heat is initiated, there is a 2 to 6 second delay while the control performs a safe start check.

2.The ignition and motor are turned on and a ﬂ ame should establish within a 15-second lockout time.NOTE:Burner will prepurge for 15 seconds if equipped with Honeywell R7184B or Beckett 7505B Control.

3.If ﬂ ame is not sensed within the 15-second lockout time, the control shuts down on safety lockout and must be manually reset by pushing the reset button on the control. If control locks over three times in a row, the control enters restricted lockout. To reset Honeywell R7184: Hold down the reset button for 45 seconds until the LED ﬂ ashes once. Beckett 7505: Hold down reset button for 15 seconds until the red LED turns off and the yellow LED turns on.

WARNING:

If furnace still doesn’t light, turn the furnace off as described above and call your technician. In the event of ﬂashback or explosion, immediately shut off furnace and call your service technician.

4.After ﬂ ame is established, the ignition remains on for 10 seconds to ensure ﬂ ame stability. It then turns off.

5.The circulating air blower will energize after the temperature fan switch closes.

6.The furnace runs until the call for heat is satisﬁ ed.

7.The circulating air blower will de-energize when the temperature fan switch opens.

Gas Gun Models

1.On a call for heat, the furnace control begins an ignition sequence which lasts approximately 45 seconds.

2.After this sequence, the control module tests to see if ﬂ ame is sensed. If it has, the furnace continues to heat until the thermostat is satisﬁ ed.

3.If the burner has not lit, the ignition sequence is repeated a maximum of two more times. If ﬂ ame is not sensed after three attempts, the control enters Lockout and no further attempts to light the burner will occur. If Lockout occurs, contact a qualiﬁ ed service technician for assistance.