c. Drive 1 factory-supplied No. 6 X 3/4-in. LG screw through each hole and tighten until furnaces are secure and foam strips have sealed
gap between furnaces.
7. Insert 1 snap bushing through each adjoining unused condensate drain line hole of each furnace.
8. Connect return- and supply-air ducts to furnaces. Seal duct connections to prevent air leakage.
9. 115-V junction boxes JB must be located on right side of right-hand furnace and left side of left-hand furnace. Relocate as necessary. (See
Fig. 29.)
10. Follow individual furnace installation instructions for upflow/downflow applications. This includes, but not limited to: condensate trap,
condensate/inducer housing tubing, pressure switch tubing venting and electrical connections.
WARNING: UNIT DAMAGE AND FIRE HAZARD
Failure to follow this warning could result in unit damage, fire, personal injury or death.
DO NOT use the back of the furnace for return-air duct connections as limit cycling will occur.
B.
Upflow/Downflow, Back-to-Back Configuration
Refer to Fig. 21 and Table 4 for appearance and dimensional drawing of twinned furnaces and their connection locations.
1. Select 2 identical heating and airflow furnaces. (See Table 4.)
2. Remove bottom closure panels from both furnaces. (See Fig. 22.)
a. Remove main and blower access doors.
b. Remove 2 screws from front filler panel.
c. Rotate front filler panel downward to remove.
d. Remove bottom closure panel and discard.
e. Reinstall front filler panel.
3. Apply 2 factory-supplied foam strips to mating back of each furnace. Locate strips equal distance from top and bottom as shown in Fig.
23. Trim off excess material.
Fig. 23—Location of Foam Strips and Hole to be Used for Twinning Kit Wire Routing
A02236
FOAM
STRIPS
UNUSED
CONDENSATE
DRAIN HOLE
FOR BACK-TO-BACK
APPLICATIONS, APPLY
FOAM STRIPS AT THIS
HEIGHT, ALONG BACK
OF FURNACE
Fig. 24—Attaching Furnaces Together
A93539
SCREW DISCHARGE
OPENINGS TOGETHER
—27—
