MG3P Installation Manual

22
Downflow Furnaces: a special mounting bracket is supplied with
the furnace for installation of the VentilAire™ supply air system.
The bracket is installed on the right hand side at the top of the
cabinet, as shown in Figure 33 (page 22). The bracket can be
secured to the unit using the self-drilling screws supplied with
the kit. Please follow the instructions provided with the kit.
Condensate Drain Lines
IMPORTANT NOTE:
If the furnace is installed in an area where temperatures
fall below freezing, special precautions must be made for
insulating condensate drain lines that drain to the outdoors.
If condensate freezes in the lines, this will cause improper
operation or damage to the furnace. It is recommended that
all drain lines on the outside of the residence be wrapped
with an industry approved insulation or material allowed
by local code.
The placement of the condensate drain lines will depend on
the configuration selected in Table 4 (page 18). The drain
lines can be routed out the left or right side of the furnace, but
must maintain a downward slope to ensure proper condensate
drainage. The J-trap may need to be rotated to the side that
matches your setup in Figure 53 (page 52) & Figure 54 (page
53). To rotate the J-trap, loosen the clamp on the drain tube,
rotate the J-trap to either side, and retighten the clamp
THREE GENERAL RULES APPLY:
• Each condensate drain line must be separately trapped using
a J-Trap or field supplied loop. After individually trapping the
condensate lines, it is acceptable to combine the drains.
• A drain must always be attached to the collector at the outlet
of the secondary heat exchanger.
• A drain must always be at the lowest point of the venting
system. NOTE: If using a condensate pump, the furnace drain
line must be installed above the pumps water line.
EXCEPTIONS & CLARIFICATIONS TO THE GENERAL
RULES:
• If venting out the left or right side of the cabinet, the vent must
be turned vertically with a tee. The drip leg formed by the tee,
reducer, and hose barb must be drained as shown in Options
2, 3, 5, 6, 8, 9, 11, & 12.
• In certain cases, the inducer may be drained back into the
collector pan (Options 1, 2, 4, 5, 7, 8, 10, & 11). Take care
that this drain tube does not sag in the middle.
• Sometimes the lowest point in the vent system is where it
connects to the inducer (Options 3, 6, 9, & 12). If the distance
between the exhaust pipe and the cabinet is 6 inches or less,
one drain at this location is sufficient. If the distance is more
than 6 inches, then another drain will need to be added to
the bottom of the tee.
Alternate Vent Pipe Installation
When running the 2” PVC pipe out through the top of the MG3S
upflow furnace, there may be possible clearance issues when
transitioning the PVC pipe from 2” to 3”.
• To increase the size of the PVC flue from 2” to 3”, you may use
two, 2” x 45° PVC elbows to achieve the clearances needed
between the coil box and the 2” x 3” neoprene coupling. See
Figure 34.
• Install the 2” x 3” neoprene coupling in the vertical run only.
If the coupling is installed horizontally, it will allow water to
build up inside the furnace and cause a lock out condition.
Filter Retainer Brack
ets
Furnace Flanges
Bent up 90°
(3 places)
Furnace Filter
NOTE: For downflow models only.
Figure 32. Filter Retainer Brackets
Figure 33. VentilAire™ Bracket
VentilAire™
Bracket
NOTE: For downflow models only.
2” PVC
Pipe
3” vent pipes
2” x 3”
Neoprene
Couplings
Coil Box
2” Neoprene
Couplings
2” x 45
0
PVC
Elbow
Figure 34. Alternate vent Pipe Installation