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73
TEMPMASTER
FORM TPM3-EG1 (518)
c.
Thrust Restraints:
Provide horizontal thrust restraints between air handling
unit casing and fan housing.
d.
Supply Fan Airflow Measurement:
The SWSI supply fan shall be supplied
with an airflow measurement device. Airflow measurement device shall be ca-
pable of measurement accuracy of +/-5%. Airflow measurement ring and trans-
ducer shall be supplied for integration into a field-supplied controller.
e.
Fan Inlet Screen:
Unit shall be provided with a fan inlet screen.
f.
Safety Grate:
Safety grates capable of supporting a 300 pound center load
shall be provided over bottom supply air (SA) opening.
3.
Fan Motor:
Fan motors shall be NEMA design ball-bearing types with electrical
characteristics and horsepower as specified. Motors shall be 1750 RPM [1175
RPM], ODP type [TEFC optional]. [Optional shaft grounding rings on motors in-
crease motor longevity when applied with a VFD.] The motor shall be located within
the unit on an adjustable base.
4.
Variable Air Volume (VAV) Fan Control:
VAV supply fan control shall be accom-
plished by using a VFD matched to the supply fan motor horsepower. The VFD shall
include an integral DC line reactor to reduce harmonic distortion in the incoming
and outgoing power feeds. If a DC line reactor is not provided, an AC line reactor
must be provided. Inlet guide vanes shall not be acceptable. VFD control keypads
shall be located in the control cabinet for accessibility and servicing while the unit
is operating.
Discharge Plenum
[SELECT ONE OF THE FOLLOWING HEAT/NO HEAT CONFIGURATIONS]
1.
Cooling Only:
The discharge air temperature (DAT) sensor shall be located in the
discharge plenum and be located such that it accurately measures the supply air
temperature (SAT). Walls shall be lined with a solid liner to prevent erosion of the
insulation and separate insulation from the air stream.
2.
Staged Gas Heat:
The heating section shall include an induced draft furnace in six
stages of heating capacity.
a.
Heat Exchanger:
The heat exchanger shall be constructed of tubular alumi-
nized steel [stainless steel] with stainless steel flue baffles and flue assembly.
b.
Burner and Ignition Control:
The burner shall include a direct-driven induced-
draft combustion fan with energy efficient intermittent pilot spark ignition, redun-
dant main gas valves with pressure regulator.
c.
Combustion Air Fan:
The inducer fan(s) shall maintain a positive flow of air
through each tube to expel the flue gas and to maintain a negative pressure
within the heat exchanger relative to the conditioned space.
d.
Safety Devices:
A high limit controller with automatic reset to prevent the heat
exchanger from operating at an excessive temperature shall be included. A cen-
trifugal switch on the induced draft fan motor shaft shall prevent ignition until
sufficient airflow is established through the heat exchanger. A rollout switch shall
provide secondary airflow safety protection. The rollout switch shall discontinue
furnace operation if the flue becomes restricted.