Furnace Components

1Combustion-air intake connection to ensure contami- nant-free air (right or left side).

2Burner sight glass for viewing burner flame.

3Burner assembly (inside). Operates with energy-saving inshot burners and hot surface igniter for safe, dependable heating.

4Redundant gas valve. Safe and efficient. Features 1 gas control with 2 internal shutoff valves. Valve appearance varies with furnace model.

5Vent outlet. Uses PVC pipe to carry flue gas from the fur- nace’s combustion system (right or left side).

6Inducer motor. Pulls hot flue gases through the heat ex- changers, maintaining negative pressure for added safety.

7Blower access panel safety interlock switch.

8Air filter and retainer (location in furnace may vary).

9Condensate drain connection. Collects moisture con- densed from burned gases for disposal into home drain system. (Location in furnace varies.)

10	Heavy-duty blower. Circulates air across the heat ex-
	changers to transfer heat into the home.

11	Secondary condensing heat exchanger (inside). Wrings
	out more heat through condensation. Constructed with
	polypropylene-laminated steel to ensure durability.

MODELS 58MCB, 58MXB, AND 58MTB

12	Primary serpentine heat exchanger (inside). Stretches fuel
	dollars with the S-shaped heat-flow design. Solid con-
	struction of corrosion-resistant aluminized steel means re-
	liability.

13	Furnace control board.

14	3-amp fuse provides electrical and component protection.

15	Light emitting diode (LED) on furnace control board.
	Status code light is for diagnosing furnace operation and
	service requirements.

16	Pressure switch(es) ensure adequate flow of flue gas
	through furnace and out vent system.

17	Rollout switch (manual reset) to prevent overtemperature.

18	Junction box for 115-v electrical power supply. (May be
	located on right or left side)

19	Transformer (24v) behind furnace control board pro-
	vides low-voltage power to furnace control board and
	thermostat.