Lennox International Inc G27M manual Filters, Two-StageOperation

6 - White Rodgers 36E Gas Valve - Turn knob on gas valve 180° either way to OFF. See figure 1.

7 - Wait five minutes to clear out any gas. If you then smell gas, STOP! Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instructions. If you do not smell gas go to next step.

WHITE RODGERS 36E SERIES GAS VALVE

p M

HI C

GAS VALVE SHOWN IN OFF POSITION

FIGURE 2

8 - White Rodgers 36E Gas Valve - Turn knob on gas valve 180° either way to ON.

9 - Replace the access panel.

10 - Turn on all electrical power to to the unit.

11 - Set the thermostat to desired setting.

NOTE – When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.

12 - If the appliance will not operate, follow the instruc& tions •Turning Off Gas to Unit" and call your service technician or gas supplier.

Turning Off Gas to Unit

1 - Set the thermostat to the lowest setting.

2 - Turn off all electrical power to the unit if service is to be performed.

3 - Remove the access panel.

4 - White Rodgers 36E Gas Valve - Turn knob on gas valve 180° either way to ON.

5 - Replace access panel.

Two–Stage Operation

The G27M is a two-stage gas-fired furnace, which can be controlled by either a two-stage or single-stage room thermostat.

The two-stage thermostat monitors the room temperature and sends a signal to the G27M furnace when the temper& ature falls below the desired setpoint. The furnace is then turned on at low fire (first stage). If the room temperatures continues to fall, the thermostat sends a signal to turn on the unit at high fire (second stage).

When a single-stage thermostat is being used to control the operation of the G27M furnace, the unit can either op& erate on high fire (second stage) at all times or the unit can be made to start on low fire (first stage) and automatically switch to high fire (second stage) after a time delay, if the demand is not satisfied on low fire (first stage).

NOTE – For more details on available options and for unit

adjustment, contact the Lennox Technical Support De-

partment.

Filters

G27M series units are equipped with external filters which should be inspected monthly and replaced when necessary to assure proper furnace operation. See table 1 for filter sizes. Replacement filters used with G27M-60/75 units must have a minimum velocity rat& ing of 400 FPM. Replacement filters used with G27M-100/120 units require a minimum velocity rating of 625 FPM. Figures 3, 4, and 5 show possible filter locations.

TABLE 1

	FILTER SIZE
MODEL NUMBER	UPFLOW	DOWNFLOW
	1 FILTER	2 FILTERS
G27M-45/60/75	16 in. X 20 in. X 1 in.	16 in. X 20 in. X 1 in.
G27M-100/120/140	20 in. X 20 in. X 1 in.	16 in. X 20 in. X 1 in.

UPFLOW FURNACE BOTTOM RETURN AIR

FIGURE 3

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