| Mechanical Specifications (contd.) Supply Fan
Supply fan shall be a single forward curved medium pressure fan secured to a solid steel shaft with grease lubricated
bearings designed for 200,000 hours. The bearings shall
have greaselines extended to a common location. The drive components shall
include fixed pitch sheaves and multiple V-belts sized
for 150% of nominal motor horsepower.
The supply fan motor shall be (choose one) A) Open
Drip-Proof, B) Totally Enclosed Fan Cooled, C) high efficiency Open Drip-Proof. Supply fan motor shall have
standard T-frame. All drive components shall be
accessible without using scaffolds or ladders.
The entire fan assembly including drive components shall be mounted on a common
base. The fan base shall be isolated inside the unit.
The entire assembly shall be statically and dynamically balanced at the factory.
Variable Air Volume (Optional)
Air flow modulation shall be by inlet guide vanes. The vanes shall rotate out of the fan inlet at full load. The inlet
vanes complete with electric actuator, linkage and
controller shall be factory installed and adjusted. The
static pressure setpoint shall be adjustable. A duct pressure sensing probe
shall be provided for field installation.
Filters
Two-inch throwaway fiberglass filters shall be provided for installation during construction. (Choose one) A) Two
inch medium velocity throwaway filters, B) Two-inch
high velocity cleanable filters shall be provided for operation.
Electric Heat (Optional)
Electric Heat including coil and controls shall be factory installed inside the
unit casing. The coil shall be open construction type.
Units with electric heat shall have single point power connection.
Unit Controls
Microprocessor controller shall control all unit functions including economizer,
mechanical refrigeration and fan modulation; and
monitor diagnostics. All controls shall be factory installed and adjusted.
Controller shall include a switch to place the unit in Auto Remote, Auto Local or Stop/Reset mode; an indicator display
to show unit operating status, diagnostics and setpoints; and adjustable setpoints for (choose all that apply) a)supply temperature,
b)zone heating temperature, c)supply air pressure,
d)economizer minimum position, e)supply air temperature control band,
f)supply air pressure control air band. The three position switch and indicator display shall be accessible without
opening any unit panels.
Self-Contained unit shall have two sets of field accessible terminals. One set shall shut the unit down when the
connection between them is open. The other set shall
turn the fan on and energize ventilation functions when the connection between
them is closed.
(Optional) Unit shall have factory mounted Disconnect Switch. The switch
shall be accessible without opening any unit panels.
(Optional) Unit shall be provided with factory mounted seven day programmable
timer to turn the unit on and off. The timer shall have
a built-in rechargeable battery back-up system. It shall be accessible without opening any unit panels.
(Optional) Reset of the supply air temperature set point based on a remote
space temperature shall be provided. The temperature at
which reset begins and the amount of reset shall be adjustable. A temperature sensor shall be provided for field installation.
Waterside Economizer (Optional)
The Waterside economizer including coil, valves, controls, and piping with cleanouts shall be factory installed in the
unit cabinet. The economizer and evaporator coils shall
be separated to permit cleaning of the fins. (Choose
one)
A) Waterside economizer coil shall be 1/2 inch seamless copper tubes expanded
into aluminum fins. Coil shall have (Choose one) a) 4
rows with no more than 12 fins per inch, b) 2 rows with no more than 14 fins per inch. The tubes shall be in a staggered
arrangement. Economizer coil shall have removable cast
iron headers and mechanically cleanable tubes. The waterside working pressure
shall be 400 psig.
B) Waterside economizer coil shall be 1/2 inch seamless copper tubes expanded
into aluminum fins. Coil shall have 4 rows in staggered
tube arrangement with no more than 12 fins per inch. Coil shall have copper headers and be chemically cleanable. The
waterside working pressure shall be 400 psig.
The waterside economizer shall be controlled to maximize hours of free cooling.
It shall be enabled whenever the entering water
temperature is 5 degrees F below the entering air
temperature. Water flow through the coil shall be proportional in response to
supply air temperature.
(Optional) Unit shall be equipped with an energy saving shutoff valve. Whenever
cooling is not required, water flow through the unit
shall be shut off.
The compressors shall be enabled during economizer operation. During compressor
operation full water flow shall be routed through the
economizer. |
