Checks And Adjustments - International comfort products N9MP1 Installation Instructions Manual

The Subbase for Combustible Floors MUST be used when a
downflow furnace is set on a combustible floor, even when the
furnace is installed on a coil box.
1. Cut the opening in the floor according to Table 13. The hole
in the floor must be cut to the dimensions listed in Table 13
since the base is equipped with locating tabs that center the
base over the opening.
The opening in the base is 1
(28.6mm) narrower than the recommended size of the opening in
the floor. This is done to maintain clearance between the floor and
the plenum.
2. Fabricate the plenum to the dimensions given in Table 13.
Note that the dimensions given are outside dimensions.
3. Set the base over the opening in the floor, centering it over
the opening. Fasten the base to the floor with screws or
nails. See Figure 41, Figure 42 and Figure 43.
4. Drop the plenum through the opening in the base. The
flange of the plenum should rest on top of the subbase.
5. Position furnace or coil cabinet and furnace on subbase so it
aligns between the locating tabs.
This subbase for combustible floors has been designed so that the
height of the subbase raises the downflow coil off the floor to allow
easy installation of the condensate drain. See Figure 44.
Exploded View of Sub−Base for
Figure 41
Furnace ONLY
T
Plenum
H
K
R
P
2"
L
(50.8mm)
M
N
Hole in
Floor
A
A = 4 1/4" (108mm) Minimum clearance from back of hole to wall or other
obstruction.

Checks and Adjustments

Verify the input rate of the furnace.
NOTE:
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in
personal injury, death and/or property damage.
Turn OFF gas at shut off before connecting
manometer.
42
1
/ " (31.8mm) shorter and 1
4
S
Combustible
Floor Base
J 2"
(50.8mm)
1"
(25.4mm)
25-20-46
Specifications are subject to change without notice
Figure 42
1
/ "
8
Figure 43
Furnace/Coil Box
Installation of
Combustible
Floor Base
Wood Screw
Figure 44
Startup
NOTE: Refer to the start−up procedures in the "User's Information
Manual" or to the "Operating Instructions Label" on the furnace.
Gas Supply Pressure
Gas supply pressure should be within minimum and maximum
values listed on rating plate. Pressures are usually set by gas
suppliers.
Exploded View of Base for
Downflow Cased Coil
2
1
Setting the Subbase
Wood Floor
Plenum
Condensate Line Raised by Base
25−20−52
1 "
/ (63.5mm)
2
1 "
/ (38.1mm)
2
25−20−46a
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