Engineering Manual

Installing the Ducts
• Use more than ten (10) screws to securely attach the supply ducts to the
unit. To prevent air leaks, seal around the duct opening before the duct is
secure.
• To prevent vibration transmission, install flexible connectors between ducts
and the unit. The flexible connectors must be made of a heat-resistant
material at the discharge connection if an electric heater is installed.
• Duct work must be insulated and covered with vapor barrier when routed
through unconditioned spaces. Include enough insulation to prevent
condensate from forming on the ducts.
• It may be necessary to add internal acoustical insulation lining for a metal
duct system if it does not include a 90° elbow and ten (10) feet between the
main duct and the first branch.
• Fibrous glass ducts could be used as a substitute if built and installed in accordance with the most recent edition of the Sheet Metal and
Air-Conditioning Contractors’ National Associate (SMACNA) standard.
• Also, fibrous duct work and acoustical insulation lining must also follow National Fire Protection Standard 90A or B as tested by UL
Standard 181 for Class 1 air ducts.
VERTICAL-HORIZONTAL INDOOR UNITS
Installation and Best Layout Practices
>10 Screws
(M4*25L)
Figure 230:Securing the Ducts to the Unit.
Installing the Drain System
General Specifications
• To prevent property damage, optimize drain system performance by installing both a primary and secondary drain line, and properly size
the condensate traps.
• The primary and secondary drain line must be trapped to allow proper drainage of condensate water. If the secondary drain line is not used,
it must be capped.
• Do not block the filter access panel when installing the condensate drain piping. Prime the primary and secondary condensate traps after
running both to the drain pan.
• If the unit is installed above an inhabited space, add a field-supplied external condensate pan that runs underneath the entire frame (to
prevent damage from overflow). The additional external condensate line should run from the unit to the external condensate pan.
• Drain all generated condensate from the external condensate pan to an appropriate area. Install a trap in the condensate lines as near to
the indoor unit coil as possible.
• All condensate should be drained from the external condensate pan to some noticeable area.
• To prevent overflow, the outlet of each trap should be positioned below its connection to the condensate pan.
• All traps should be primed, insulated, and leak
tested if located above an inhabited space.
• Use a 3/4-inch PVC male pipe thread fitting at
the condensate pan connection. Tighten gently.
• Point the drain hose down for easier flow.
• Do not just use the pipe joint or PVC / CPVC
piping on the indoor unit drain line connections.
Use only Teflon tape.
• Design the drain system to plan for winter opera-
tion (condensate line may freeze up if conden-
sate does not properly drain away).
Field-Supplied
Drain Pan
Drain Piping
Field-Supplied
Drain Pan
Drain Piping
Figure 231:Vertical Installation Drain System. Figure 232:Horizontal Installation Drain System.
VERTICAL-HORIZONTAL | 167
Vertical-Horizontal Air Handling
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