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UL listed; wattage, voltage, phase, and number of steps as indicated.
Provide control-circuit terminals and single source of power supply. Heater
5 Kw and larger shall be three-phase, with load balanced on each of the
three phases. Limit leaving air temperature below 60 degrees C at 15.5
degrees C 140 degrees F at 60 degrees F entering air.
2.1.4.1
Casing
Minimum [21] [_____] gage steel.
2.1.4.2
Heating Element
Nickel-chromium heating wire element, free from expansion noise and 60 Hz
hum. Embed element in magnesium-oxide insulating refractory. Seal element
in high-mass steel or corrosion-resisting metallic sheath with fins.
Enclose element ends in terminal box. Space fins at maximum six fins per
inch. Limit fin surface temperature 288 degrees C 550 degrees Fat any
point during normal operation.
2.1.4.3
Controls
Include limit controls for thermal overheat protection of heaters. For
remote thermostatic operation, provide contactor rated for 100,000 duty
cycles. [Provide a control transformer to supply 120-volt thermostat
control circuit for each heater.] Provide room thermostat for pilot duty.
2.1.4.4
Wiring
Completely factory-prewired to terminal strips, ready to receive branch
circuit and control connections for 60 degrees C 140 degrees F[copper] [or]
[aluminum] wiring.
[2.1.4.5
Accessories
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NOTE: These accessories are not integral components
of electric unit heater. Delete this paragraph if
not required.
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Provide fan switching devices to independently operate fan motor for summer
ventilation and winter heat recovery.
]2.2
INFRARED HEATERS
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NOTE: Check if Section 15768, "Electric Space
Heating Equipment," covers electric unit heater.
Recommend to cover unit heaters exclusively in this
section. Avoid redundant statement.
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[Reflector-beam spread] [and] operating conditions as indicated. Provide
pre-wired control boxes, thermostats, and reflector [and duct] hangers.
2.2.1
Sheet Metal
[a.
Aluminum-Clad Steel:
ASTM A 463/A 463M, nominal thickness of
SECTION 15760N
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