Bulletin 30-015.003
Copyright © 2017 Unico Inc.
Page 6
Figure 4 Supply plenum adapter, square duct
To attach the plenum adapter to the unit, align the
holes on the adapter with the holes located around the
supply outlet on the unit. Mount the adapter with eight
(8) sheet metal screws.
For metal duct, attach the plenum to the adapter by
inserting it over the collar. Use three (3) or four (4)
equally spaced sheet metal screws to secure the duct to
the collar and then tape around the seam with UL 181A
aluminum tape. Then wrap the 1-in fiberglass blanket
duct insulation around the adapter and seal with UL
181A aluminum tape.
Other size plenum may be used provided it is similar in
cross-sectional area. Refer to the design manual for
alternate sizes.
Return Duct
The Unico return air system typically has a single return
that includes the return air box with filter, the acoustical
flex return duct, and the return air adapter. Multiple
returns or extra-long returns are possible so long as the
maximum pressure loss is not exceeded. The return
system is designed for a maximum static pressure drop
of 0.15 inches of water (37 Pa) including the filter. The
return duct should have at least one 90 degree bend
between the unit and filter box to reduce sound
transmission directly from the unit.
The return air must always enter the unit from the
bottom. Set the unit on a field fabricated duct (figure 5)
or use a field supplied plenum base. If using a duct, be
sure that the inside of the duct is insulated with
acoustical insulation (typically duct liner). The
minimum height of the plenum duct is shown in figure
5.
Figure 5 Minimum duct return
Although Unico only supplies a single return system,
the return system can be redesigned for multiple
returns. The return duct system is not high velocity.
Therefore, the return system static pressure should not
exceed 0.15 inches of water column. Generally, this
means sizing the duct for a pressure loss of 0.05 inches
of water column at the required airflow and sizing the
filter for a pressure drop of 0.10 inches of water
column at the required airflow.
It should also have some form of sound attenuation.
Sound attenuation can be accomplished with fabricated
duct board, lined sheet metal, or acoustical flex. For
best attenuation, always have at least one 90 degree
bend to eliminate direct line-of-site from the unit to the
return opening.
AIR FILTRATION
The unit includes a 1 inch (25 mm) thick pleated filter
(Table 2). You can remove this filter (Figure 6) and
replace it with a 2” filter or install another filter
elsewhere in the system. See figure 7 and table 3 for a
plenum base concept and filter size.
Table 2 Unit Filter Size, 1 inch (25 mm)
Model
Filter Part No.
Dimensions, inch (mm)
2430
A00558-005
18 x 18 (457 x 457)
3036
A00558-008
18 x 22 (457 x 559)
3642
A00558-009
21 x 22 (533 x 584)
IL00545.cvx
Part No.
UPC-62-2430
UPC-62-3036
UPC-62-3642
A
8.5 (216)
10.5 (267)
10.5 (267)
Part No. (R-6)
UPC-62R6-2430
UPC-62R6-3036
UPC-62R6-3642
A
9.5 (241)
11.5 (292)
11.5 (292)
Model
V2430
V3036
V3642
Airflow
Note: UPC-62-3036 and UPC-62-3642 are identical.
A
1 (25)
2
(52)
A
H (min.)
IL0546.cvx
Model
H, inch (mm)
2430
8 (200)
3036
8 (200)
3642
10 (250)
Area, in
2
(m
2
)
150 (0.10)
180 (0.12)
240 (0.15)
Area (min.)
