Furnace Controls & Functions; Furnace On / Off Switch; Limit Control; Gas Valve - Nordyne M1MB 056 Installation Instructions Manual

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 Furnaces (M1B 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.
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. 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 33.

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 33.

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 "slow-open" for M1M and M1B models
which means it opens to a low-fi re position, and after a
few seconds, "steps-open" to high-fi re.

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 33.
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
Switch
Furnace
On-Off
Switch
Oil
Pump
Figure 33. Furnace Controls - Oil Furnace
Lower
Limit
Switch
Fan
Control
Oil
Burner
Control
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