15619-2
GAS FIRED SEPARATED COMBUSTION AIR HANDLING UNITS
blower assembly, and electrical control unit with all specified components and
internal accessories factory installed and tested and prepared for single-point high
voltage connection.
2.3 CABINET
A. Materials: Formed, double wall insulated metal cabinet, fabricated to permit access
to internal components for maintenance.
1. Outside casing: 18 gauge, galvanized steel meeting ASTM A653 for
components that do not receive a painted finish. Pre-painted components as
supplied by the factory shall have polyester urethane paint on 18 gauge
galvanized steel. Base rail is 12 gauge, galvanized steel.
2. Internal Assemblies: 24 gauge galvanized steel except for motor supports which
shall be minimum 14 gauge galvanized steel.
B. Comply with NFPA 90A and NFPA 90B and erosion requirements of UL 181.
1. Materials: Fiberglass insulation. If insulation other than fiberglass is used, it
must also meet the Fire Hazard Classification shown below.
a. Thickness: 1 inch
b. Fire Hazard Classification: Maximum flame spread of 25 and smoke
developed of 50, when tested in accordance with ASTM C 411.
c. Location and application: Floor of each unit shall be insulated with either
one half inch thick or 1 inch thick rigid fiberglass insulation, covered on
one surface with integral aluminum foil.
C. Access panels: Unit shall be equipped with removable access panels to provide easy
access to all major components. Access panels shall be fabricated of 18 gauge steel.
Removable access panels shall incorporate a formed drip edge.
D. Supply Air blower assembly: Blower assembly consists of an electric motor and a
belt driven, double width, double inlet forward curve blower. Assembly shall be
mounted on heavy gauge galvanized rails and further mounted on minimum 1.125
inch thick neoprene vibration isolators.
E. Control panel / connections: Unit shall have an electrical control center where all high
and low voltage connections are made. Control center shall be constructed to permit
single-point high voltage power supply connections.
F. Indirect Gas-Fired Furnace:
1. Integral combustion gas blower.
2. Fault sensors to provide fault conditions to optional digital controller or
building controls.
3. 4-pass tubular heat exchangers, constructed of type 409 stainless steel. Heat
exchanger tubes shall be installed on the vest plate by means of swaged
assembly, welded connections are not acceptable. Heat exchanger tubes shall
be supported by a minimum of two fabricated assemblies that support the tubes
and also permit expansion and contraction of the tubes.
4. Weather-tight metal housing with intake air vents.
5. | Hinged door shall provide access to the enclosed vest plate, control circuitry,
gas train, burner assembly and exhaust blower.
6. Shall include a kit for outdoor mounting with vertical stack venting.
G. Dampers: Motorized intake air dampers of low leakage type shall be factory installed.
13089K
