Main Burner Adjustment; Safety Controls Functions & Check Out Procedures - Goodman GMN SERIES Installation & Operating Instructions Manual

Gas furnaces

Table of Contents

MAIN BURNER

After furnace has been in operation for approximately five minutes, close the air shutters until yellow tips appear on the flames.

Now open the air shutter until yellow tips just disappear and the flames have soft blue cones. Repeat this procedure on all

burners. Lock the air shutters by means of the lock screw.

AIR SHUTTER

LOCKING SCREW

SAFETY CONTROLS FUNCTIONS AND CHECKOUT PROCEDURE

GENERAL

In most cases all safety switches used on this furnace are wired in series through the furnace "W" leg. It is important never

to bypass, alter or tamper with any safety control on this furnace. Safety features of this furnace must be checked at time

of installation to assure proper operation of the furnace.

MAIN LIMIT SWITCH

High limit switch used is a 1/2" dia. disk switch, designed to shut off the gas to the burners if the outlet air exceeds the max.

design outlet temperature. High limit cut-off is non-adjustable. To check the control operation, block the air flow through the

unit temporarily. The limit switch should function to turn off the automatic gas valve within a few minutes. Remove blockage

immediately after switch operates.

VENT PRESSURE SWITCH

This furnace uses a vent pressure switch to prevent the furnace from operating if the vent blower should fail to operate or a

restriction in the venting system occurs. DO NOT tamper with or bypass this switch. For more details of the venting

installation see the section titled "VENTING". To check this switch remove the hose from the vent motor with the burners

ignited. The switch should function and turn off the burners immediately. Reinstall the rubber hose and the burners should

ignite.

FLAME ROLL-OUT SWITCH

This furnace is equipped with (2) flame roll-out switches. These 1/2" dia., manual reset switches are located in the burner

vestibule. These switches are designed to shut down the burners in event presence of flame is detected outside the heat

exchanger. To reset the switch you must depress the button on the top of the switch. With the furnace in operation place

an open flame (candle, match, cigarette lighter etc.) under this switch with the flame touching the sensing element. The

switch should function in a short time and the burners should extinguish. Reset the switch.

FLAME SENSOR

Main burner ignition is provided by a Hot Surface ignition system. The main burners should extinguish if the flame sensor

fails to detect burner flame. Disconnect the sensor lead to the module. Place the furnace into operation. The ignitor should

glow, the burners ignite; however the burners should shut off after a few seconds of operation. Reconnect the sensor lead

and follow the lighting instructions to restore the furnace to its operational condition.

BLOWER DOOR INTERLOCK SWITCH