Applications in moderate climates can be specified
at the designer's option.
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Heaters shall be in accordance with ANSI Z83.4. Direct fired make-up air
heaters use outside air directly ducted to the heater. The products of
combustion generated by the heater are released into the outside air stream
being heated. Heaters shall be equipped with [motorized [inlet] [and]
[outlet]] [backdraft] dampers, [discharge air diffuser,] [duct collar,]
[air filters,] [and] [bird screen]. Gas control valve shall be
[single-stage] [two stage] [modulating] type. Maximum air temperature rise
during minimum burner fire shall be 4 degrees C 7 degrees F.
Fan shall be
[single-speed][two speed, with low speed approximately two-thirds of high
speed][variable speed]. Outdoor heaters shall be weatherized and shall
have manufacturer's standard exterior finish for outdoor units. Motorized
[inlet] [and] [outlet] dampers shall be closed when the unit is shut down.
Dampers shall be interlocked to prevent burner operation when dampers are
closed. Heaters shall be provided with a [space] [discharge air]
thermostat, a low limit air stream thermostat, and an ambient air
thermostat. The [space] [discharge air] thermostat shall control the gas
control valve. The low limit air stream thermostat shall shut down the
entire unit if the discharge air temperature drops below the [space]
[discharge] thermostat setting. The ambient air thermostat shall shut down
the burner if the outside air exceeds the [discharge] [space] thermostat
setting.
2.3.2
Indirect Fired Make-Up Heaters
Heaters shall be in accordance with ANSI and CGA Standards. Heaters shall
be equipped with motorized inlet dampers, duct collar, and air filters.
Gas control valve shall be modulating type. Maximum air temperature rise
during minimum burner fire shall be 4 degrees C 7 degrees F. Fan shall be
two speed, with low speed approximately two-thirds of high speed.
Motorized inletdampers shall be closed when the unit is shut down. Dampers
shall be interlocked to prevent burner operation when dampers are closed.
Heaters shall be provided with a space thermostat, a low limit air stream
thermostat, and an ambient air thermostat. The space thermostat shall
control the modulating gas control valve. The low limit air stream
thermostat shall shut down the entire unit if the discharge air temperature
drops below the space thermostat setting. The ambient air thermostat
shall shut down the burner if the outside air exceeds the space thermostat
setting.
2.3.3
Unit Heaters
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NOTE: Aluminized steel heat exchangers will be
satisfactory in most applications. Omit the
aluminized if there is a corrosive condition.
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Heaters shall conform to requirements of ANSI Z83.8. Heat exchangers shall
be [aluminized steel] [or] [stainless steel]. Air discharge section shall
be equipped with adjustable [horizontal louvers] [and] [vertical louvers or
fins]. Fan shafts shall be either directly connected to the driving motor,
or indirectly connected by multiple V-belt drive. Fans in one unit shall
be of the same size. Heaters shall be power-vented type, suitable for
sidewall vent discharge and single-wall-thickness vent piping. Heaters
shall have automatic ignition. Heaters shall employ metered combustion air
SECTION 15565A
Page 8
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