Performing Routine Maintenance, For 58MTB and 58MVB

After the hot surface igniter is heated for 17 seconds, the gas valve permits gas to ﬂow to the main burners. After ignition and a time delay of about 60 sec, the furnace blower will start. Variable-capacity furnaces start at low speed until the control makes the necessary adjustments to operate the blower at either the low- or high-heat speed.

NOTE: If the burners fail to ignite after 4 attempts, the fur- nace control system will lock out. If lockout occurs, main burners fail to light, or blower does not come on, shut down the furnace and call your dealer for service.

12.Set your thermostat to the temperature that satisﬁes your comfort requirements.

SUGGESTION: Setting the thermostat back a few degrees—and compensating for the difference with warmer clothing—can make a big difference in your fuel consumption. The few degrees at the top of your thermo- stat “comfort level’’ are the most costly degrees to obtain.

When the room temperature drops below the temperature selected on the thermostat, the furnace will switch on auto- matically. When the room temperature reaches the tempera- ture selected on the thermostat, the furnace will be switched off automatically.

	22
OFF	ON

Some thermostats have a FAN mode with 2 selections:AUTO and ON. When set on AUTO, the furnace blower cycles on and off. In the ON mode, the furnace blower runs continu- ously. Continuous fan keeps the temperature level in your home more evenly balanced. It also permits the indoor air to be continuously ﬁltered. ComfortFan™ –On all but the 58MCB, the blower speed can be increased or decreased if desired due to change of seasons, large gatherings in your home, etc. Simply change your FAN from ON to OFF for 1 to 3 seconds (or AUTO depending on your thermostat), and then return to ON. The blower will switch to the next higher speed. There are at least 3 speeds to choose from. If the blower is running on its highest speed, a request to change will direct the blower to return to its lowest speed.

SHUTTING DOWN YOUR FURNACE

Should you ever need to shut down your furnace for service or maintenance, you will need to turn the furnace off. The following procedures must be followed:

1.Set your room thermostat to the lowest temperature setting. (See Fig. 21.)

2.Close the external manual gas valve (See Fig. 11.)

3.Turn off electrical supply to the furnace. (See Fig. 22.)

4.Remove main furnace door. (See Fig. 13.)

5.Turn the switch on the gas control to the OFF position. (See Fig. 23 or 24.)

For 58MTB and 58MVB

	M	1
O	P	3
F	C	2
F	C	2

For 58MCB and 58MXB

6.Replace the main furnace door. (See Fig. 18.)

7.If the furnace is being shut down because of a malfunc- tion, call your dealer as soon as possible.

! CAUTION

UNIT AND PROPERTY DAMAGE

Failure to follow this caution may result in damage to the furnace and other property damage. Furnace is not to be installed, operated, and then turned off and left turned off in an unoccupied structure during winter. (See “Heading South for the Winter” procedures in maintenance section on page 10).