Step 5 — Select and Install Ductwork
The design and installation of the duct system must be in accordance with the standards of the NFPA for installation of
Select and size ductwork,
!WARNING
PERSONAL INJURY AND ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury or death.
For vertical supply and return units, tools or parts could drop into ductwork Install a 90 degree turn in the return ductwork between the unit and the conditioned space. If a 90 degree elbow cannot be installed, then a grille of sufficient strength and density should be installed to prevent objects from falling into the conditioned space. Units with electric heaters require 90 degree elbow in supply duct.
When designing and installing ductwork, consider the following:
1.All units should have
2.Avoid abrupt duct size increases and reductions. Abrupt change in duct size adversely affects air performance.
IMPORTANT: Use flexible connectors between ductwork and unit to prevent transmission of vibration. Use suitable gaskets to ensure weather tight and airtight seal. When electric heat is installed, use fireproof canvas (or similar heat resistant material) connector between ductwork and unit discharge connection. If flexible duct is used, insert a sheet metal sleeve inside duct. Heat resistant duct connector (or sheet metal sleeve) must extend
3.Size ductwork for cooling air quantity (cfm). The minimum air quantity for proper electric heater operation is listed in Table 2. Heater limit switches may trip at air quantities below those recommended.
4.Seal, insulate, and weatherproof all external ductwork. Seal, insulate and cover with a vapor barrier all ductwork passing through conditioned spaces. Follow latest Sheet Metal and Air Conditioning Contractors National Association (SMACNA) and Air Conditioning Contractors Association (ACCA) minimum installation standards for residential heating and air conditioning systems.
5.Secure all ducts to building structure. Flash, weatherproof, and
CONFIGURING UNITS FOR DOWNFLOW (VERTICAL) DISCHARGE
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before performing service or maintenance operations on the system, turn off main power to unit and install lockout tag.
1.Open all electrical disconnects and install lockout tag before starting any service work.
2.Remove horizontal (metal) ductcovers to access vertical (downflow) discharge duct knockouts in unit basepan. (See Fig. 6.)
3.To remove downflow return and supply knockout covers, break front and right side connecting tabs with a screwdriver and hammer. Push cover down to break rear and left side tabs.
Horizontal Duct Covers
A09076
Basepan |
| |
Downflow |
| |
(Vertical) | Basepan | |
Supply | ||
Downflow | ||
Knockout | ||
(Vertical) | ||
| ||
| Return | |
| Knockout |
A09093
Fig. 6 - Supply and Return Duct Opening
NOTE: These panels are held in place with tabs similar to an electrical knockout. Reinstall horizontal duct covers (Fig. 6) shipped on unit from factory. Insure openings are air and watertight.
NOTE: The design and installation of the duct system must be in accordance with the standards of the NFPA for installation of
Adhere to the following criteria when selecting, sizing, and installing the duct system:
1.Units are shipped for side shot installation.
2.Select and size ductwork,
607C-- -- A
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