26
441 01 2613 05
Specifications are subject to change without notice
Table 5
Sub
!
bases for Combustible Floors Dimensions in(mm)
Sub
!
base for
Combustible Floors
Part Number
Sub
!
base for Combustible
Floor Dimensions
Opening In Floor
Opening In
Base For Plenum
Typical Plenum
Dimensions
H
*
J*
K**
L
M
N
P
R
S
T
Subbase for Furnace Only
NAHH001SB
15
11
/
16
(398.5)
28
3
/
4
(730.3)
14
9
/
16
(369.9)
16(406.4)
16
1
/
4
(412.8)
14
5
/
8
(371.5)
15 (381)
13
1
/
2
(342.9)
15 (381)
13
1
/
2
(342.9)
NAHH002SB
19
5
/
16
(490.5)
28
3
/
4
(730.3)
18
3
/
16
(462)
16(406.4)
16
1
/
4
(412.8)
18
1
/
4
(463.6)
15 (381)
17
1
/
8
(435.6)
15 (381)
17
1
/
8
(435.6)
NAHH003SB
22
15
/
16
(582.6)
28
3
/
4
(730.3)
21
13
/
16
(554)
16(406.4)
16
1
/
4
(412.8)
21
7
/
8
(555.6)
15 (381)
19
3
/
4
(501.7)
15 (381)
19
3
/
4
(501.7)
Subbase for Coil Box
NAHH004SB
15
3
/
4
(25.4)
20
9
/
16
(522.3)
14
9
/
16
(369.9)
16
1
/
16
(408)
16
1
/
4
(412.8)
14
5
/
8
(371.5)
15 (381)
13
1
/
2
(342.9)
15 (381)
13
1
/
2
(
342.9)
NAHH005SB
19
3
/
8
(181.1)
20
9
/
16
(522.3)
18
3
/
16
(462)
16
1
/
16
(408)
16
1
/
4
(412.8)
18
1
/
4
(463.6)
15 (381)
17
1
/
8
(435.6)
15 (381)
17
1
/
8
(435.6)
NAHH006SB
23 (284.2)
20
9
/
16
(522.3)
21
13
/
16
(554)
16
1
/
16
(408)
16
1
/
4
(412.8)
21
7
/
8
(555.6)
15 (381)
19
3
/
4
(501.7)
15 (381)
19
3
/
4
(501.7)
*
Outside Dimension
**
Base Spacer Side To Side
Converstion: 1 in = 25.4 mm
Figure 29
Exploded View of Base for
Downflow Cased Coil
25-21-65n
2
1
/
2
″
1
1
/
2
″
Plenum
(63.5mm)
(38.1mm)
Sub-base for Combustible Floors - Downflow Coil
Adapter Box
The subbase for combustible floors is required when a downflow
furnace,
used with a downflow coil box
, is set on combustible
flooring.
1. Cut the opening in the floor according to the dimensions in
Table 5
because the base is equipped with locating tabs that
center the base over the opening.
The opening in the base is 1
1
/
4
″ 〈
31.8mm) shorter and 1
1
/
8
″
(28.6mm) narrower than the minimum required size of the
opening in the floor. This is done to maintain a 1” (25.4mm)
clearance between the floor and the plenum.
2. Fabricate the plenum to the dimensions given in
Table 5
.
Note that the dimensions given are outside dimensions.
3. Set the base over the opening in the floor, centering the
opening in the base over the opening in the floor. Fasten the
base to the floor with screws or nails. See
Figure 28.
4. Drop the plenum through the opening in the base. The flange
of the plenum should rest on top of the combustible floor base.
Consideration must be given to the height of the base to allow for
easy installation of the condensate drain. See
Figure 30
. 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
Condensate Line Raised by Base
Figure 30
25
!
20
!
52
Non-Combustible Floor
Set the furnace over the opening in the floor. If necessary, grout
around the base to seal air leaks between the base and the floor.
Duct Connections
In the downflow position, the return
!
air duct must be connected to
only the top of the furnace. Top return connections can be made by
removing the knockout panel in the furnace base. Return air
connection through the side(s) or back of the furnace is
NOT
allowed.
Duct Design and Duct Installation Requirements
See
Section 10
.
Internal Filter in Top Return Installation
When installing top
!
mounted filter inside the furnace, install the
filter clips on the edge of the top duct opening with the wider end of
the clips toward the blower as shown in
Figure 31
. Clips may be
obtained from
your distributor or fabricated from sheet metal
National Excelsior Company
www.excelsiorhvac.com
Subject to change without notice.
