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TYPE AND DESCRIPTION

Furnish an I.C.E HTDM DX Model indirect fired self-contained make-up
air unit with packaged cooling in accordance with the following specifications.
The unit shall be ETL and CETL certified.

The heater shall be designed to ensure a minimum efficiency of 80
- 85% at full firing rate and the power burner has a turndown capacity
between 23:1 and 60:1 depending on the HTDM selection.  The heat
exchanger and blower shall be constructed so they can easily be disassembled
and reassembled in the field if necessary. The unit shall be equipped
to operate from a single point power connection. The heater shall be
flame tested before shipment and the manufacturer shall keep a detailed
flame test report on file. Factory testing shall be confirmed with a
combustion analyzer and flow meter. The heater shall be shipped completely
factory assembled and wired including all pre-piped manifold components
and fuses, ready for immediate power and fuel connections.

CASING

The unit exterior casing shall be heavy gauge G90 rated bonderized
steel. Unit roof shall feature standing seam construction. The entire
unit casing shall be insulated with 1-in. thick 1.5-lb. (2-in. thick
1.5-lb.) fiberglass insulation with hard neoprene backing in a sandwich
wall fashion (22-gauge solid liner). The unit exterior shall be finished
with industrial enamel (catalyzed epoxy) paint. An integral welded iron
channel frame shall support the unit casing. The structural iron frame
shall be sandblasted, primed and finished with industrial enamel (catalyzed
epoxy) paint.

BLOWER/MOTOR SECTION

The fan section and motor assembly shall be constructed in accordance
with the requirements of the Air Moving and Conditioning Association
(AMCA). The assembly shall be designed to house the fan(s), bearings,
motor, and v-belts, which shall be selected for at least 50% above the
rated motor capacity. The fan(s) and motor shall be mounted on a welded
unitary base made of angle iron frame. The frame shall be sandblasted,
primed and finished with industrial enamel (catalyzed epoxy) paint.
The unitary base shall be provided with seismic spring vibration isolation.
The blower section shall have a hinged access door with Ventlock handles
to allow easy maintenance of filters and belts. The NEMA T-Frame motor
shall be mounted on an adjustable base located within the fan section.
The blower shall be a forward curve DWDI centrifugal blower. The blower
wheel shall be statically and dynamically balanced, and mounted on a
turned, ground and polished shaft with rigid bearing supports. The shaft
shall be designed with a maximum operating speed not exceeding 75% of
the first critical speed. The bearings shall be split taper lock ball
bearing type L<sub>20 minimum life of 100,000 hours (L<sub>10
200 kHr).

Fan performance
shall be based on tests conducted in accordance with AMCA Standard Test
Code for Air moving Devices.  (All fans shall have sharply rising
pressure characteristic extending throughout the operating range and
continuing to rise well beyond the efficiency peak to assure quiet and
stable operation under all conditions. Horsepower characteristics shall
be truly non-overloading and shall reach a peak in the normal selection
area.) Fan manufacturer shall provide sound power ratings in the eight
octave bands, which shall be based on AMCA Standard 300-67, test, setup
number one. Sound power ratings shall be referenced 10-12 watts. A factory
dynamic balance shall be made on all fans after their assembly. An IRD
or PMC analyzer shall be used to measure velocity, and the final reading
shall not exceed 0.1 inches per second. The exact level of vibration
shall be recorded on the fan as proof of the final dynamic balance at
the factory.

HEAT EXCHANGER

The heat exchanger shall be of two-pass design, made up of at least
16-gauge stainless steel drum and tubes.  The primary and secondary
heat transfer surfaces shall be constructed of Type 409 series stainless
steel, with internal stainless steel high efficiency enhancing baffles.
The stainless steel tubes shall be continuously welded into the secondary
front and rear header tube sheets to ensure an airtight seal. After
welding, the heat exchanger shall be pressure tested to 20 psi to ensure
that there are no leaks. Manufacturer shall provide complete pressure
testing report with Installation Manual.  Failure to provide this
report will result in a 10% holdback.  Units shall be provided
with multiple condensate drains.  The heat exchanger section shall
have an internal radiation shield to maintain a jacket loss of less
than 2% of rated output. All heat transfer surfaces, including headers
and the front collector box, shall be inside the casing and in the airstream.
The construction of the heat exchanger shall permit free, unrestricted
lateral, vertical, and peripheral expansion during the heating and cooling
cycle without damage or strain to any parts. The burner shall be constructed
with at least 14-gauge stainless steel and with the air baffles being
made up of 430 stainless steel to ensure high durability and life of
the burner.  The burner assembly shall be a blow through positive
pressure type with an intermittent pilot ignition system.  Flame
supervision shall be with a solid state programmed flame relay complete
with flame rod.  The units burner motor and modulating gas valve
must be electronically controlled to guarantee, to the customer, a highly
efficient unit at all times and applications.  The unit efficiency
shall be a minimum of 80 - 85% through the entire operating range depending
on which HTDM selection is used and shall be independently tested and
verified by ETL.  The main and pilot manifolds shall be completely
factory pre-piped to the burner.  This assembly must be factory
wired and include the following minimum components: main and pilot manual
shut-off valves, main and pilot regulators, main and pilot automatic
shut-off valves and adequate union and test ports for unconstrained
service.  HTDM 200, 400 and 600 indoor units can be vented using
type B vent without a draft hood.  HTDM 1000 and 1500 indoor units
can be vented using type B vent with a diverter to assure safety and
guarantee that all combustible gases leave the unit.  There must
also be a means of collecting and disposal of condensate formed in the
flue gas by means of a 409 stainless steel flue box with drain and heat
exchanger drain.  Drains shall be made of stainless steel tubing.

  

HEATING CONTROLS

Units must be controlled electronically to achieve a turndown of at
least 23:1 and to guarantee the heat exchanger efficiencies of at least
80%.  Unit controller must be a true proportional integral decay
(PID) controller to maintain the turndown and unit efficiencies. 
The controller must be able to electronically adjust the burner blower
and modulating gas valve to maintain ideal combustion levels and shall
monitor the amount of combustion air available to guarantee proper emission
standards.  Unit control will consist of a highly accurate feedback
control system.  Corrective action in this system is taken only
when the balance has been upset due to a change in the disturbance variable. 
Any other control that does not behave in this manner is unacceptable. 
The ICECON2 controller analyzes the process and calculates a control
error from the measured values. Continuous cycling of the burner or
blower is unacceptable.  The proportional control in the ICECON2
controller will provide an output signal in proportion to the size of
the control error.  If the control error persists, the output will
continue to ramp in the correct direction, until the control error is
eliminated.

The ICECON2 modulation controller is compatible with
the following external inputs:

Discharge air sensor.
Discharge ai