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2.4 Ductwork (cont'd)
Air balancing dampers are recommended for both supply and exhaust ducts to allow for adjustment of airfl ow. Also, fl exible canvas
connectors should be installed close to the unit in the supply duct to the building and the exhaust duct from the building to reduce
noise transmission from the unit to the building, see Appendix C.
All ports on the B6LC and B12LC units have 1" (25 mm) fl anges to facilitate the installation of the ductwork. Please note that the
"Fresh Air from Outdoors" port has a defrost damper incorporated with it.
Ensure that any mechanical fasteners used to connect the duct do not interfere with the operation of the damper. Screws can be
installed on the side of the cabinet rather than the fl ange for this port only. For port locations see Appendix B.
2.5 Internal Grilles and Diffusers
Locate exhaust grilles and supply diffusers to provide effective ventilation and avoid short circuiting of airfl ows. Adjustable dampers
should be provided at every grille and diffuser location to make balancing of the system possible.
A proper selection of style and size of grilles and diffusers is required to minimize pressure drop. The velocity of the airfl ow should not
exceed 400 ft./min. (2 m/sec.) for normal applications.
The duct system should be designed according to the high speed fl ow rate of the unit. In order to keep the noise and pressure drop
to a minimum, a maximum air velocity of 1100 ft./min. (5.6 m/sec.) should be used in calculations in duct design. The duct runs should
be kept as short as possible with the minimum amount of elbows and transitions.
The manufacturer recommends the use smooth radius elbows or square elbows with turning vanes to achieve maximum performance.
2.6 Exterior Hoods
It is important that the fresh air intake hood be positioned well away from any source of contamination. The exterior supply and
exhaust hoods must be separated enough to prevent cross-contamination and at an elevation that will prevent blockage by snow, dirt
and leaves.
NOTE: Consult local building code for restrictions in your area.
A rodent screen with 1/4" (6 mm) mesh must be installed to prevent the intake of large debris and animals. A backdraft damper may
need to be installed in the exhaust duct to prevent cold air entering the building if the unit is to be shut off for a long period of time.
To maintain optimum airfl ow performance, exterior hood selection must be such that the minimum free area of opening is as follows:
140 inches2 (0.09 m2).
2.7 Drains
The drain fi ttings provided with the unit will accept a 3/4" (19 mm) NPT coupler (supplied by others). The drain line for the unit must
be fabricated on-site and connected to the building main. A loop in the hose or trap in the copper or plastic pipe must be provided to
prevent sewer gases from entering the unit when connecting to a drain as illustrated in Appendix D.
NOTE: Consult local building code for plumbing requirements in your area. If copper pipe is to be used, ensure not to solder to the
3/4" (19 mm) coupler while it is attached to the plastic drain fi tting as deformation may occur. Ensure adequate slope is present
to allow good drainage (minimum 1/4" per foot or 6 mm per 305 mm).
2.8 Electrical Connections
P
OWER
A terminal block and strain relief bushing or a junction box is provided for line voltage to make the necessary power connections.
The electrical requirements are as follows:
2. Installation (cont'd)
B6LC
VOLTAGE
120 V
MCA
9.50 A
MOP
15.00 A
5
B12LC
120 V
14.30 A
20.00 A
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