SECTION 15855 - AIR HANDLING UNITS
CONSTRUCTION STANDARD
PART 1:
1.01
1.02
Purpose:
A.
The design guidelines contained herein include the requirements for air handling
systems and appurtenant devices at The University of Texas at Austin. It is the
intention of this document to provide a standard for the design of Air Handling
Units at the University that represents the highest level of quality and consistency
possible; it is not intended to be a guide specification.
B.
Factory built air handlers shall be limited in size by the cross sectional area of its
casing. The corss section shall accommodate no more than one coil with
maximum dimensions described in Section 15857. It is UT Austin's desire to use
built-up air handler casings. See Section 15856. Where conditions demand
factory built air handlers the consultant shall justify use to UT Austin.
Quality Assurance:
A.
Manufacturer's Qualifications: Firms regularly engaged in manufacture of
packaged air handling units with characteristics, sizes, and capacities required,
whose products have been in satisfactory use in similar service for not less than 5
years.
B.
Codes and Standards to be followed as University Standard:
C.
1.03
GENERAL
1.
AMCA Compliance: Test and rate air handling units in accordance with
AMCA standards.
2.
ARI Compliance: Test and rate air handling units in accordance with ARI
430 "Standard for Central-Station Air Handling Units", display
certification symbol on units of certified models.
3.
NFPA Compliance: Provide air handling unit internal insulation having
flame spread rating not over 25 and smoke developed rating no higher
than 50; and complying with NFPA 90A "Standard for the Installation of
Air Conditioning and Ventilating Systems".
4.
UL and NEMA Compliance: Provide electrical components required as
part of air handling units, which have been listed and labeled by UL and
comply with NEMA Standards.
5.
NEC Compliance: Comply with National Electrical Code (NFPA 70) as
applicable to installation and electrical connections of ancillary electrical
components of air handling units.
Asbestos:
In no instance will any product containing asbestos be acceptable
for use.
Submittals:
Design & Construction Standards, Revised May 6, 2002
15855-1
SECTION 15855 - AIR HANDLING UNITS
CONSTRUCTION STANDARD
A.
Product Data: Submit manufacturer's technical product data for air handling units
showing dimensions, weights, capacities, ratings, fan performance with operating
point clearly indicated, motor electrical characteristics, gages, finishes of
materials, and installation instructions.
B.
Shop Drawings: Submit assembly-type shop drawings showing unit dimensions,
weight loadings, required clearances, construction details, and field connection
details.
C.
Maintenance Data: Submit maintenance instructions, including instructions for
lubrication, recommended lubricant, filter replacement, motor and drive
(including belts) replacement, and recommended spare parts lists. Include this
data, product data, shop drawings, and wiring diagrams in maintenance manuals,
in accordance with requirements of Division 1.
D.
Motor Data: Submit manufacturer's product data indicating compliance with
Motor Standard Section 15170.
PART 2:
2.01
PRODUCTS
Acceptable Manufacturers:
A.
Manufacturer: Subject to compliance with requirements, provide air-handling
units of one of the following:
1.
2.
3.
4.
5.
6.
7.
2.02
Governaire
Buffalo Forge
LaSalle
Marcraft
Pace, Co.
Energy Labs
Thermal
Factory Built Packaged Air Handling Units:
A.
General: Provide horizontal or vertical type factory-fabricated air handling units
as indicated, of sizes and capacities as scheduled, and as specified herein.
B.
Casings: Each unit shall have a double wall airtight and weatherproof casing and
shall be sectionalized for placement (indoors or outdoors). Casings shall be
designed, manufactured, and installed such that no condensation shall form on the
exterior or interior surfaces (other than in cooling surfaces). Manufacturers who
do not meet this criteria on any job shall be removed from the “Acceptable
Manufacturer” list for a period of 2 years. Casing shall be constructed of "lock
forming" quality galvanized steel, phosphatised steel, or bonderized steel.
Phosphated or bonderized metal shall be finished with rust inhibiting paint.
Casing shall also be finish painted. For maximum rigidity, casing shall be
properly reinforced and braced with steel angle or square tubular framework and
Design & Construction Standards, Revised May 6, 2002
15855-2
SECTION 15855 - AIR HANDLING UNITS
CONSTRUCTION STANDARD
have the same finish as the unit casing. Casing shall at a minimum consist of a
fan section, coil sections, filter section, and access sections. Additional sections
may be required per drawings. Suitable gaskets shall be provided at all joints
between casing sections. Stiffeners shall be provided, to prevent unit casing
pulsation. Exterior skin shall be minimum twenty (20) gauge and interior skin
shall be a minimum of sixteen (16) gauge. The entire floor of the unit, including
fan sections, shall have a 3/16” aluminum diamond plate over the insulation to
protect it from scuffs and abrasion. Each section shall be supplied with two
opposite end drain connections except where indicated otherwise. (See
Condensate Drain Pan.) Unit casings shall be insulated internally with four (4)
inch thick, 3# density Johns-Manville "Lina-Coustic", "Exact-O-Mat", "TuffSkin", or "Aeroflex". The insulation shall be installed in such a manner that it
will not be disturbed by the removal of a panel, and shall be protected by the
interior skin of the unit. Unit casing shall be constructed and assembled to
withstand operating pressure of up to 6: w.g. positive with a maximum leakage
rate of 1% of total airflow.
C.
Coil Section: The coil section shall completely enclose the coil headers and
return bends. Coil frames shall not be used as structural members of the coil
section. The coil section shall be constructed in such a manner that the coils can
be removed without affecting the structural integrity of the casing.
D.
Coils: Refer to Sections 15857 and 15858
E
Condensate Drain Pan: The drain pan shall not extend under the complete coil
section, including headers, and shall be rigid and watertight with two opposite end
1-1/2" male NPT stainless steel pipe drain connections extending 2 inches beyond
the outside wall of the unit casing, or with drain connections as indicated on
drawings. The drain pan shall be of the singleware insulated type with a 16gauge,
type 304 stainless steel (heliarced seams) inner pan with stainless steel drain
nipples and a galvanized, or painted, outer pan. Insulation shall be 1" thick,
flexible unicellar. Drain pans shall not recess into floor of casing.
F
Filter Section (Dual Filter): Provide filter sections to allow for 2" thick, prefilter,
dry type, moderate efficiency and 12" high efficiency final filter. Prefilter shall be
of filter media with an average efficiency of 25% - 30% on ASHRAE Test
Standard 52 - 76 and an average arrestance of 94 - 96%. Final filter shall be of
filter media with an average arrestance of not less than 99%.
Provide for removal of from upstream
G
Filter Section (Single Filter): Provide flat filter sections with hinged access doors
on each end of the section. Furnish 4" thick, dry type, moderate efficiency (25%
to 30%) when tested in accordance with ASHRAE Test Standard 52-76), pleated
media, disposable filters, equal to Farr 30/30.
Refer to schedule on drawings for single or dual filtering requirements only filter
sizes of 24” x 24” and 24” x 12” face are acceptable.
H
Access: Insert from back Provide double wall insulated walk-in access doors in
each section with windows, hinges, and quick opening handle with locking latch.
Design & Construction Standards, Revised May 6, 2002
15855-3
SECTION 15855 - AIR HANDLING UNITS
CONSTRUCTION STANDARD
Doors shall be 24" x 48" in heating unit and 24" x 60" in cooling unit, except
where indicated otherwise on drawings.
I.
J.
PART 3:
3.01
1.
Provide surface mounted magnahelic gauge for each prefilter and final
filter bank, with integral leveling screw and graduated to read from 0 to 1"
w.g.
2.
Provide pressure tips, tubing, gauge connections, and mounting bracket.
Fans:
Refer to Fan Section of this standard
EXECUTION
Field Quality Control:
A.
3.02
Filter Gauges:
Testing: Upon completion of air handling unit installation, supplier shall
supervise start-up and operate equipment to demonstrate capability and
compliance with requirements. Supplier shall field correct malfunctioning units
and then retest to demonstrate compliance.
Extra Stock:
A.
Provide one complete extra set of prefilters for each air-handling unit. Install new
filters at completion of air handling system testing, adjusting, and balancing work.
Obtain receipt from Owner that new filters have been installed.
END OF STANDARD 15855
Design & Construction Standards, Revised May 6, 2002
15855-4