Nordyne M1S General-Direct Ignition Models, FURNACE IF YOU SMELL GAS Operating instructions for

e.When the call for heat is satisfied the thermo- stat contacts open, the gas valve shuts off gas flow, and the induced draft blower stops.

GENERAL-DIRECT IGNITION MODELS

Read safety information on front page of these installation instructions before operating fur- nace. DO NOT ATTEMPT TO OPERATE

FURNACE IF YOU SMELL GAS.

Operating instructions for

M1M — MODELS WITH DIRECT IGNITION:

a. STOP! Read the SAFETY INFORMATION. b. Set the thermostat to the lowest setting. c. Turn off all electric power to the appliance. d. This appliance is equipped with an ignition

device which automatically lights the burner. Do not try to light the burner by hand.

e.Honeywell - push in the gas control knob and turn clockwise to “OFF.” Robertshaw - push the gas control lever to “OFF.” NOTE: The lever cannot be placed in the “OFF” position unless it is pushed in slightly. DO NOT FORCE (See Figures 30 & 31).

GAS CONTROL KNOB

Figure 30. Direct Ignition

Gas Valve - Honeywell

Gas Control

Figure 31. Direct Ignition

Gas Valve - Robertshaw

f.Wait ten (10) minutes to clear out any gas. If you smell gas, STOP! and follow step “d” in the SAFETY INFORMATION section. If you do not smell gas, go to the next step.

g.Set the On-Off switch to the “ON” position.

h.Honeywell - turn knob on gas control counter clockwise to “ON.” Robertshaw - push the gas control lever to “ON.”

i.Turn on all electric power to the appliance.

j.Replace the furnace door.

k.Set the thermostat to “HEAT” and the desired temperature setting. The furnace should light after approximately 75 seconds. If the appli- ance will not operate, follow the instructions “To Turn Off Gas To Appliance” and call your service technician or gas supplier.

In the event of any flashback or explosion, immediately shut off the furnace and call your service technician.

TO TURN OFF GAS APPLIANCE:

a. Set the thermostat to the lowest setting.

b. Turn off all electric power to the appliance before servicing unit.

c. Set the ON-OFF switch to “OFF.”

d.Honeywell - push in the gas control knob and turn clockwise to “OFF.” Robertshaw - push the gas control lever to “OFF.”

e.Replace the furnace door.

SEQUENCE OF OPERATION FOR M1M MODELS WITH DIRECT IGNITION

Direct ignition model furnaces do not have a pilot. Ignition is accomplished automatically by a silicon carbide hot surface ignitor. A control module takes care of all timing functions. After lighting, the control module uses the ignitor as a flame sensor, shutting off gas should the flame go out. There are no external relays or timing devices.

Do not try to light this furnace manually. The control module is not field serviceable. a. On a call for heat, the thermostat contacts close, supplying 24 VAC between terminals “C” and “W” of the control module, which

starts combustion motor.

b. When the inducer starts, the air pressure switch closes at -0.20”WC differential pres- sure and energizes the control.

c. After a 45 second purge period, the ignitor is energized for a 30 second warm-up period, after which the gas valve opens.

d.The trial period for ignition is approximately 6 seconds, after which the gas valve either

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