Nordyne AND M5S, SERIES M1B installation instructions Furnace Controls & Functions

4.When call for heat is satisfi ed, the thermostat contacts open and the gas valve shuts off gas fl ow.

WARNING:

Should overheating occur, or the gas supply fails to shut off, shut off the manual gas valve to the furnace before shutting off the electrical supply.

AVERTISSEMENT:

En case de température excessive, ou sail est impossible de cooper l’alimentation en gaz, fermer le robinet manuel d’alimentation en gaz du générateur d’sir chaud avant de cooper l’alimentation électrique.

FURNACE CONTROLS & FUNCTIONS

Furnace On-Off Switch

This switch turns electrical power to the furnace on and off. The switch must be set in the ON position for the furnace to operate. For M1G models, in warm weather there is a possibility of the blower turning on periodically or operating continuously due to a heat buildup within the furnace by a combination of warm weather and heat from the pilot. This is normal operation as long as there is power to the furnace and the furnace On-Off switch is in the ON position. If blower operation is not desired, the furnace On- Off switch may be set in the OFF position to cut the electrical power to the furnace.See Figure 35.

Limit Control

This furnace is protected by two high temperature safety limit switches. The auxiliary (upper) limit switch and the high temperature (lower) limit switch are automatic reset types. If either limit trips, the burner will shut off. If either limit switch trips off again soon after resetting, set the furnace furnace On-Off switch to the OFF position and call your authorized serviceman. See Figure 35.

Gas Valve

The gas valves for the gas furnaces are a 100% shut-off type and will fail safe, if for some reason the gas is turned off. The valve is a “step-open” type for M1G models and “slow-open” for M1M and M1B models which means it opens to a low-fire position, and after a few seconds, “steps- open” to high-fi re.

Roll Out Switch (M1G - 056 & 070)

The furnace is protected by a manual reset safety switch located on the bottom left hand side of the combustion pipe.

Oil Burner Primary Control

The primary control for oil gun furnaces starts the burner, monitors a safe operating cycle, and shuts the burner off at the end of a heating cycle. The control uses a light sensing transducer to determine if fuel ignition has been successfully attained. If ignition is not attained by the end of the safety ignition timing period, the control shuts the burner off and enters“lock-out.”See Figure 35.

Summer Cooling - (B, C, & D Series)

Your furnace is A/C ready, equipped with A/C relay and transformer. The unit is equipped to use a 4-wire thermostat. When using a 5-wire thermostat, RC and RH should be jumped (see instructions included with thermostat).

Upper
Limit	Lower
Switch	Limit
	Switch
Furnace	Fan
On-Off
	Control
Switch
	Oil
	Burner
	Control
Oil
Pump

Figure 35. Furnace Controls - Oil Furnace

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