**SPECIAL SPECIFICATION**

**SECTION 15855**

**[AIR HANDLING UNITS]{.underline}**

[Page]{.underline}

PART 1 - GENERAL

1.01 Work Included 2

1.02 Related Work 3

1.03 Definitions 3

1.04 Performance Criteria 3

1.05 Submittals 4

1.06 Extra Stock 4

PART 2 - PRODUCTS

2.01 Acceptable Manufacturers 5

2.02 Fabrication And Design 5

2.03 Casing 5

2.04 Fan Section - Centrifugal, Plug Fan, And Axial Fan 7

2.05 Coils 10

2.06 Mixing Box Section 12

2.07 Access Modules 12

2.08 Filter (Housings) 12

PART 3 - EXECUTION

**SPECIAL SPECIFICATION**

**SECTION 15855**

**[AIR HANDLING UNITS]{.underline}**

[PART 1 - GENERAL]{.underline}

1.01 [WORK INCLUDED]{.underline}

A. This section provides for furnishing and installing air handling
units for heating, ventilating, air conditioning, and evaporative
cooling and make-up air.

B. Each air handling unit may have all or part of the following
components (see drawing for layouts).

1\. Blower section.

a\. Centrifugal.

b\. Plug fan.

c\. Axial fan.

2\. Hot water heating coil.

3\. Steam heating coil.

4\. Chilled water cooling coil.

5\. Evaporative section.

6\. Access section.

7\. Filter section (Filters or Prefilter & Bag Filter)

8\. Mixing box section.

9\. Mixing box/filter section.

1.02 [RELATED WORK]{.underline}

A. [Vibration Limits and Control]{.underline}. Section 15200.

B. [Ductwork Systems]{.underline}. Section 15890.

C. [HVAC Controls and EMCS System]{.underline}. Section 13943.

D. [System Component Checkout and Balance]{.underline}. Section 15901.

E. [Motors and Starters]{.underline}. Division 16.

1.03 [DEFINITIONS]{.underline}

A. [Low Pressure Units]{.underline}. Total static pressures up to 3
inches w.g.

B. [Medium Pressure Units]{.underline}. Total static pressures above and
up to 6 inches w.g.

1.04 [PERFORMANCE CRITERIA]{.underline}

> Unit capacities and characteristics are scheduled on the drawings.
> Each air handling unit shall have physical dimensions suitable to fit
> space allotted to the unit. Performance shall be based on elevation
> 5310\' level conditions.

A. [Fan Performance Ratings]{.underline}. Conform to AMCA 210 and bear
the AMCA Certified Rating Seal.

B. [Sound Ratings]{.underline}. AMCA 301; tested to AMCA 300 and bear
AMCA Certified Sound Rating Seal.

C. [Fabrication]{.underline}. Conform to AMCA 99 and ARI 430.

D. [Filter Media]{.underline}. ANSI/UL 900 listed, Class I or Class II.

E. [Air Coils]{.underline}. Certify capacities, pressure drops and
selection procedures in accordance with ARI 410.

1.05 [SUBMITTALS]{.underline}

A. Submit shop drawings and product data in accordance with Section
01300.

B. Shop drawings shall indicate assembly, unit dimensions, weight
loading, required clearances, construction details, and field connection
details.

C. Product data shall indicate dimensions, weights, capacities, ratings,
fan performance, motor electrical characteristics, and gages and
finishes of materials.

D. Provide fan curves with specified operating point clearly plotted.

E. Submit sound power levels for both fan outlet and casing radiation at
rated capacity.

1.06 [EXTRA STOCK]{.underline}

> Provide one complete matched set of drive belts for each AHU and one
> set of filters for each AHU.

[PART 2 - PRODUCTS]{.underline}

2.01 [ACCEPTABLE MANUFACTURERS]{.underline}

A. Trane.

B. Pace.

C. McQuay.

2.02 [FABRICATION AND DESIGN]{.underline}

A. [General]{.underline}. Fabricate units with fan, coil, mixing
box/filter section, access section, and cooling coil sections plus
accessories as indicated on drawings.

B. [Structural Requirements]{.underline}

1\. Provide factory assembled modular units. Large units may be shipped
in assembled sections.

2\. Furnish units with sealing and fastening hardware supplied by the
manufacturer. Include written instructions needed to complete field
assembly of the components.

3\. Provide units designed and constructed so that coils, panels, fan
housing and fans can be removed without affecting the structural
integrity of the unit.

2.03 [CASING]{.underline}

A. [Construction]{.underline}. All module sections (except fan sections)
of components shall be 2\" thick double-wall constructed. Interior wall
shall be of 18-gauge solid plate galvanized steel for components and
perforated plate galvanized steel for 4\" thick double-wall plug fan
housing. Foil faced insulation is not acceptable.

B. [Access]{.underline}. Provide access to all sections of the unit by
removable access panels big enough to permit removal of internal parts.
Provide gasketing ont he casing to seal access panels. Provide fan and
coils section access doors with ventlock hinges and latches.

C. [Finish]{.underline}. Paint with one shop coat of industrial primer,
or galvanize all parts of the unit, both inside and out, including belt
guard and supports. On painted units, add a coat of industrial enamel to
the exterior.

D. [Insulation]{.underline}. Insulate casing sections with 1-inch thick,
1-1/2 lbs. per cu. ft. density, neoprene coated, glass fiber insulation,
\"K\" value at 75 F maximum 0.26 Btu/inch/sq.ft./degrees F/hr, applied
to internal surfaces with adhesive and weld pins. Coat exposed edges of
insulation with adhesive. Insulation with adhesive. Insulation and
adhesive: conform to NFPA 90A. Insulation shall not breed or promote
fungi or bacteria, shall resist mold growth, shall not rot or sustain
vermin.

E. [Drain Pan]{.underline}. Provide the double-bottom type drain pan
with 1/2-inch or more foam insulation in a sealed space between the two
pans.

1\. Inside pan shall be all-welded construction and shall be coated with
waterproofing material or shall be stainless steel. Cross break and
pitch to drain connection.

2\. Provide a large threaded drain connection on both sides at the low
point of the pan.

3\. When two or more cooling coils are used,with one stacked above the
other, individual drain troughs of galvanized steel with water-proofing
material or stainless steel piped to the main drain pan shall be
provided beneath each of the coils.

F. [Supports]{.underline}. Provide suitable legs or support rods and
clips as required to ensure adequate support of the complete unit. Use a
suitable suspension system for suspended units.

2.04 [FAN SECTION - CENTRIFUGAL, PLUG FAN, AND AXIAL FAN]{.underline}

> Provide double-inlet, squirrel-cage, centrifugal fans, with die-formed
> impeller blades. Fans should be designed for quiet, slow-speed
> operation under specified rating conditions.
>
> Primary air handling unit fan shall be single width, single inlet,
> multi-blade type plug (plenum) fans. The fan blades shall be backward
> inclined airfoil (AF).
>
> Plug fans shall be equipped with self-aligning, anti-friction split
> pillow block bearings with a minimum life of L-50 400,000 hours.

A. [Wheels]{.underline}. Furnish wheels of rigid steel or aluminum
construction, mechanically fastened to a common shaft. Coat steel wheels
with approved zinc-rich coat after fabrication. For coating, use
Zincilate, Sealube, Amercoat, or diametcoat. Balance wheels statically
and dynamically. Design and test for continuous operation at maximum
rated static pressure.

B. [Scrolls]{.underline}. Provide fan scrolls of steel construction.
Rigidly secure the scrolls in the casing to prevent vibration.

C. [Shafts]{.underline}. Provide solid hot rolled steel, ground and
polished, with keyway and protectively coated with lubricating oil.

D. [Bearings]{.underline}

1\. Provide fan with self-aligning ball or roller type bearings selected
for 200,000 hours minimum average life under actual load and speed
conditions.

2\. Furnish adjustable block or flange mount bearings for accurate
alinement of fan wheels in the scrolls.

3\. Bear shall be permanently lubricated or lubricated type with
lubrication fitting externally accessible at the drive side of the unit.

4\. Bearing shall be supported by structural shapes, or die-formed sheet
structural members, or support plates securely attached to the unit
casing.

5\. Bearings shall not be fastened directly to the unit sheet metal
casing.

6\. Blower wheels cantilevered on the ends of the shafts are not
acceptable.

7\. Provide non-removable dust caps on the bearings.

E. [Drive]{.underline}. Provide fans with a motor-driven V-belt designed
for not less than 150 percent of connected motor horsepower.

1\. Furnish an adjustable-pitch motor sheave selected to produce
specified capacity when set approximately at midpoint, and to provide
not less than 20 percent variation in speed from full open to full
closed. Key the fan sheave to the fan shaft.

2\. Nonadjustable motor sheaves may be used for motors larger than 15
horsepower, provided that if for any reason it becomes necessary to
change the sheave to produce specified capacity, replacement will be
done at no additional cost.

F. [Belt Guard]{.underline}. Fabricate to SMACNA Low Pressure Duct
Construction Standards, of 12-gage, 3/4-inch, diamond mesh wire screen
welded to steel angle frame or equivalent, prime coated. Secure to fan
or fan supports without short circuiting vibration isolation, with
provision for adjustment of belt tension, lubrication, and use of
tachometer with guard in place.

G. [Motors]{.underline}

1\. Provide grease-lubricated ball bearings with alemite fittings. For
additional requirements, refer to Electrical Motors, Division 16.

2\. Mount the fan drive motor on an adjustable base and arrange for
positive and easy adjustment of drive alinement and belt tension.

3\. Provide fan motors that will not overload when scheduled fan rpm is
increased 10 percent. Submit a fan curve for each scheduled unit showing
operating points at scheduled conditions and at scheduled rpm increased
10 percent.

4\. Motors shall be 1750 rpm, TEFC, rated for 480 volts, 3 phase, 60
hertz.

H. [Axial Fans]{.underline}

1\. Constant volume units, air foil, In-line, axial flow, belt driven,
fixed blade.

2\. Housing: 14-gauge steel with integral inlet bell and diffuser,
painted finish of beige enamel.

3\. Inlet/Outlet Shells: Tapered inlet/outlet shells over fan hub.

4\. Fan Wheel: Aluminum casting with radially projected blades of
air-foil cross section, factory dynamically balanced and keyed to fan
shaft.

5\. Diffuser: Cast aluminum with 29 radially projected straightening
vanes of air-foil cross section.

6\. Shaft: Solid AISI - C1040 hot rolled steel turned and polished.

7\. Bearings: precision, flange mounted, self aligning ball bearings at
inlet/discharge, grease lubricated with avg. life of 200,000. Extended
grease lines to exterior of shell.

8\. Motor: High efficiency, ODP, outside of air stream.

9\. Accessories: Inlet/outlet flanges, adjustable inlet vanes for
pneumatic operations outlet flow stabilization screen (only on four
smoke removal units).

10\. MFR: Trane Company, Model \"Q\".

2.05 [COILS]{.underline}

> Provide coil section with coils and access to both sides of coils.
> Enclose coils with headers and return bends exposed outside or fully
> contained within casing. Slide coils into casing through removable end
> panel with blankoff sheets and sealing collars at connection
> penetrations.

A. [Standards]{.underline}. Supply products of leading manufacturers
with dependable published ratings, or equal. Certify performance in
accordance with latest edition ARI Standard 410. Submit coil descriptive
literature and rating information for review.

B. [Fabrication]{.underline}. Construct coils of copper tubes with
aluminum fins bonded to the tubes.

1\. Mount in a galvanized steel casing permitting removal of coil from
unit. Coil sections shall have heavy-duty coil tracks extending the full
width of the unit.

2\. Fins may be either plate type,with tubes mechanically bonded into
the fins, or ribbon type, helically wound on individual tubes. Provide a
tight, mechanical bond between fins and tubes. Use a minimum of six and
a maximum of ten fins per linear inch (25 mm) of tube.

3\. Design coil section to prevent condensate carryover at face
velocities 15 percent greater than design velocities.

C. [Water Coils]{.underline}. Provide chilled water/coils. Balance the
circuits for equal pressure drop of no more than 10 feet on coils of six
rows or fewer, nor more than 15 feet for coils with eight rows or more.

1\. Arrange each circuit for counterflow cooling with bottom supply
connections. Provide drain and vent connections at bottoms and top.
Furnish access holes and covers. Locate coil headers at the same end of
the coil.

2\. Select water coil for approximately 3 to 4 feet per second velocity
minimum, 5 fps (maximum). Provide minimum .020-inch wall tubes and
.010-inch fins. Each coil shall be tested at the factory under water at
not less than 250 psi air pressure and shall be suitable for 200 psi
working pressure.

3\. Supply and return connections shall be clearly marked.

D. [Heating Coils]{.underline}

1\. Hot water (180°F). Provide hot water coils, minimum two rows deep
except where otherwise noted. Design and construct hot water coils the
same as cooling coils.

2\. Steam.

a\. Internal face and by-pass type with by-pass air flowing through
vertical dampered openings in coil construction. Casing: 14 ga.
galvanized with baked enamel finish.

b\. Frame: Rigid structural steel, galvanized with banked enamel finish.

c\. Coils: Aluminum fin, replaceable seamless copper tubes brazed to
headers.

Headers: Heavy duty, Sch. 40 tubular steel.

d\. Dampers: Preadjusted linkage, 16 ga. steel dampers, damper rods to
rotate in nylon bearings, dampers with baked enamel finish.

e\. Face and by-pass channels: 16 ga. galvanized steel.

f\. MFR: Wing Company, IFB Series.

2.06 [MIXING BOX SECTION]{.underline}

> Provide internally insulated, manufacturer\'s mixing box section with
> automatic dampers for mixing return air and outside air at top, bottom
> and rear as indicated on the drawing.

2.07 [ACCESS MODULES]{.underline}

> The access modules shall be provided by the air handling unit
> manufacturer, engineered to be used with the AHU unit. All access
> modules shall be medium size unless otherwise noted.

2.08 [FILTER (HOUSINGS)]{.underline}

A. [Slide Racks]{.underline}. Provide and arrange suitable galvanized
filter slide racks to permit easy removal of filters from the accessible
side of unit.

[PART 3 - EXECUTION]{.underline}

A. Install in accordance with manufacturer\'s written instructions and
in conformance with ARI 435.

B. Install unit on vibration isolators.

C. Do not operate units for any purpose, temporary or permanent, until
ductwork is clean, filters are in place, bearings lubricated, and fan
has been test run under observation.

END OF SECTION