DUCTING
The proper sizing of warm air ducts is necessary to insure satisfactory heating operation. Ductwork should be in accordance with the latest editions of (U.S.)
Ductwork Recommendation:
The supply duct work should be attached to the flanged opening provided at the discharge end of the furnace. See page 3 "Furnace Specificatons" for the dimensions of this opening.
A left, right, or bottom return air opening must be used as determined by the layout of the installation. The
back must not be cut out for return connections. An externally mounted air filter is required.
This furnace has a two piece bottom panel. For bottom or end duct return, remove the back portion of the bottom panel by removing the four (4) screws - two (2) on each side toward the back of the furnace (See Figure 7). Tilt furnace toward the front, the back portion of the panel will drop down. Then the back portion can be removed by pulling toward the back of the furnace.
Figure 7
BOTTOM PANEL REMOVAL
Knockouts are provided on both sides of the furnace to facilitate the cutout required to the return air ductwork.
Furnace cutouts must be the full size specified by the corner markers. Undersized cutouts will adversely affect the airflow capability of the furnace and could cause overheating of the heat exchanger.
The following recommendations should be followed when installing the ductwork:
1.Install
2.Noncombustible flexible duct connectors are recommended to connect both the supply and return ducts to the furnace.
3.In cases where the return air grille is located close to the blower inlet, there should be at least one 90° air turn between blower and return grille. Further reduction in sound can be accomplished by installing acoustical air turning vanes and/or lining the inside of the duct with acoustical material.
4.It is recommended that the supply duct be provided with a removable access panel. This opening shall be accessible when the furnace is installed and shall
be of such a size that the heat exchanger can be viewed for possible openings using light assistance or a probe can be inserted by sampling the air stream. The access panel shall be designed so as to prevent leaks when locked in position. If an air conditioning coil is installed, the access panel to the coil can be used for this purpose.
When supply ducts carry air circulated by the furnace to areas outside the spaces containing the furnace, the return air shall also be handled by a duct sealed to the furnace casing and terminating outside the space containing the furnace. Incorrect ductwork termination and sealing will create a hazardous condition that could lead to bodily harm.
Air openings, intake and outlet pipes, return air grilles and warm air registers must not be obstructed.
To Convert to Downflow Position:
1.Convert the combustion blower to side flue exit, as outlined on page 14.
2.Install proper special base per Table 2 for installation on combustible flooring (follow instructions supplied with special base).
3.It is recommended that the return air be connected to the bottom panel of the furnace when it is installed in the downflow position.
NOTE: SPECIAL
Table 2
SPECIAL BASE INSTALLATION
MODEL | SPECIAL BASE | CAT. NO. | |
NUMBER | |||
|
| ||
|
|
| |
AV050B3 | 20066501 | 68L77 | |
AV075B3 | |||
|
| ||
|
|
| |
AV100B4 | 20066502 | 68L78 | |
|
|
| |
AV125B5 | 20066503 | 68L79 | |
|
|
|
NOTE: Installation on combustible flooring only when installed on one of the above listed special bases or as identified on the furnace model and rating label.
20571201 | Issue 0527 | Page 11 of 28 |