Lennox International Inc R/LBR, R/LUF Lubrication, Combustion and Ventilation Air, Return Air

airflow. This can cause heat exchanger failure or cooling coil freeze-up along with the accompanying costly service calls.

The dealer may have changed the filter size, so the information provided in Table 1 may not apply to your installation.

Always measure the original filter and replace with the same size and type.

Factory-Supplied Filters

Models	Size
R/LUF	16" x 25"
R/LBF, R/LBR (57/72, 84/95)	18" x 19"
R/LBF, R/LBR (112/125)	19" x 21"
R/LBR (140/168)	20-1/8" x 22-7/16"
R/LBR (168/196)	24-5/8" x 24-3/8"

Models R/LHF and R/LHR are not equipped with factory- supplied filters. The filters for these units are supplied in the field.

Table 1

Upflow Units

To replace the filter in an upflow unit, refer to the following directions and Figure 2.

Side Return

To replace the filter in a furnace with an external filter rack or cabinet on either side of the furnace cabinet:

1.Turn off the power to unit.

2.The filter(s) may be removed by sliding toward the front. Replace in a reverse procedure.

Bottom Return

To replace the filter in a furnace with a bottom return air:

1.Turn off the power to unit.

2.Remove lower front panel by lifting up and pulling out.

3.The filter(s) may be removed by sliding toward the front. Replace in a reverse procedure.

Upflow Units: Filter Replacement

Front

Panel

Side

Panel

R/A

Duct

Base

Filter	Filter Rack	Filter
(slides in from front of unit)
	Side Return	Bottom Return

Basement Units

To replace the filter in a basement unit (see Figure 3):

1.Turn off power to unit.

2.Remove lower rear panel by lifting up and pulling out.

3.The filter(s) may be removed by sliding out through the rear of the furnace. To reinsert, place filter on the two filter supports and slide into unit.

Basement Units: Filter Replacement

Filter

Supports

Filter	Rear
	Of
	Furnace

Figure 3

Restore power to the furnace after the door or panel has been replaced and check furnace for proper operation. If the unit does not operate, call your dealer for service.

Lubrication

Lubrication of the bearings in the circulating air blower motor and the combustion blower motor is not recommended.

Combustion and Ventilation Air

Adequate air must reach your furnace to provide for proper and safe operation. Any obstruction of this airflow can cause an unsafe condition which may result in death or permanent injury. Lethal carbon monoxide gas can be produced if combustion air is restricted.

Furnaces located in a closet, alcove, or utility room must have provision for adequate air supply by means of upper and lower grilles in the door, or by the introduction of outside air, or both.

National codes and local code requirements are generally alike. However, local codes take precedence.

Venting and Furnace Support

Venting of this furnace must comply with our published instruc- tions. If the installer has not followed these requirements, you should request the installer to comply as soon as possible.

Make sure all flue product materials external to the furnace are clear and free of any obstruction, slope upward, and have no holes or leaks.

It is important that the outside area where the vent terminates is kept clear of any obstructions which might block or impede the venting of the furnace.

Should any unusual conditions be observed during your inspections, call your authorized service dealer at once.

Return Air

Check that all return air duct connections are tight and sealed to the furnace cabinet and that all return air grilles or registers are located outside the space containing the furnace.

# 44886B001

Figure 2

Page 3