Lennox International Inc Gas Units, G61MP Series Units Integrated Control Board, Unit Start−Up

Integrated Control Board

G61MP units are equipped with a two−stage integrated control. This control manages ignition timing and fan off delays based on selections made using the control DIP switches and jumpers. The control includes an internal watchguard feature which automatically resets the ignition control when it has been locked out. After one hour of con- tinuous thermostat demand for heat, the watchguard will break and remake thermostat demand to the furnace and automatically reset the control to relight the furnace.

DIP Switch Settings −− Figure 53

Switch 1 −− Thermostat Selection −− This unit may be used with either a single−stage or two−stage thermostat. The thermostat selection is made using a DIP switch which must be properly positioned for the particular application. The DIP switch is factory−positioned for use with a two− stage thermostat. If a single−stage thermostat is to be used, the DIP switch must be repositioned.

a − Select " for two−stage heating operation con- trolled by a two−stage heating thermostat (factory set- ting);

b − Select " for two−stage heating operation con- trolled by a single−stage heating thermostat. This set- ting provides a timed delay before second−stage heat is initiated.

Switch 2 −− Second Stage Delay (Used with Single− Stage Thermostat Only) −− This switch is used to deter- mine the second stage on delay when a single−stage ther- mostat is being used. The switch is factory−set in the OFF position, which provides a 10−minute delay before second− stage heat is initiated. If the switch is toggled to the ON position, it will provide a 15−minute delay before second− stage heat is initiated. This switch is only activated when the thermostat selector jumper is positioned for SINGLE− stage thermostat use.

Switches 3 and 4 −− Heating Blower−Off Delay −− The heating blower−on delay of 45 seconds is not adjustable. The heating blower−off delay (time that the blower operates after the heating demand has been satisfied) can be ad- justed by moving switches 3 and 4 on the integrated control board. The unit is shipped from the factory with a heating blower−off delay of 90 seconds. The heating blower off delay affects comfort and is adjustable to satisfy individual applications. Adjust the blower off delay to achieve a sup- ply air temperature between 90° and 110°F at the exact moment that the blower is de−energized. Longer off delay settings provide lower supply air temperatures; shorter set- tings provide higher supply air temperatures.Table 11 pro- vides the blower off timings that will result from different switch settings.

TABLE 11

Heating Blower−Off Delay Switch Settings

Blower Off Delay	Switch 3	Switch 4
(Seconds)
60	Off	On
90	Off	Off
120	On	Off
180	On	On

Switch 5 −− Cooling Blower−Off Delay −− The cooling blower−off delay (time that the blower operates after the cooling demand has been satisfied) can be adjusted by moving switch 5 on the integrated control board. The switch is factory−set in the OFF position, which provides a cooling blower−off delay of 45 seconds. If the switch is toggled to the ON position, it will provide a 2−second cool- ing blower−off delay

On−Board Jumper W951 −− Figure 53

On−board jumper W951, which connects terminals R and O on the integrated control board, must be cut when the fur- nace is installed in applications which include a heat pump unit and a thermostat which features dual fuel use. If the jumper is left intact, terminal

inating the HEAT MODE in the heat pump. On−Board Jumper W915 −− Figure 53

On−board jumper W915, which connects terminals Y1 and Y2 on the integrated control board, must be cut if two−stage cooling will be used. If the jumper is not cut the outdoor unit will operate in first−stage cooling only.

Unit Start−Up

FOR YOUR SAFETY READ BEFORE OPERATING

WARNING

Do not use this furnace if any part has been under- water. A flood−damaged furnace is extremely dan- gerous. Attempts to use the furnace can result in fire or explosion. Immediately call a qualified ser- vice technician to inspect the furnace and to replace all gas controls, control system parts, and electrical parts that have been wet or to replace the furnace, if deemed necessary.

WARNING

Danger of explosion. Can cause injury or product or property damage. Should the gas supply fail to shut off or if overheating occurs, shut off the gas valve to the furnace before shutting off the electrical supply.

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