York ECO R-407C - Manual (Page 38)

YORK INTERNATIONAL 38
Guide Specifications
GENERAL
Units shall be designed for outdoor rooftop installation
on a roof curb. Units shall be rated according to ARI
360. Units shall be shipped in a single package, fully
charged with HFC-407C refrigerant. The manufactur-
ing facility shall be registered under ISO 9001 Quality
Standards for Manufacturing. All units shall be com-
pletely factory assembled and run tested.
Units shall be ETL listed and be tested according to UL
1995. Tags and decals to aid in the service or indicate
caution areas shall be provided. Installation, operation
and maintenance manuals shall be supplied with each
unit.
Units shall be capable of providing mechanical cooling
down to 45° F (0°F with a low ambient kit). Unit shall be
capable of starting and running at 120° F. Unit electric
and gas connections shall be either through the curb or
the side of the unit.
CONSTRUCTION
Base
The base rail shall be constructed of 12 gauge galva-
nized steel, extending the full perimeter of the unit. All
components shall be supported from the base, and the
base shall include integral lifting lugs. The unit base
rail shall overhang the roof curb for water runoff and
shall have a fabricated recess with a continuous flat
surface to seat on the roof curb gasket, providing a
positive, weather tight seal between the unit and the
curb.
Casing
The unit cabinet shall be double wall construction to
provide both maximum resistance to bacterial growth
in the air stream and superior structural integrity. All
sheet metal shall be G90 mill galvanized sheet metal,
formed and reinforced to provide a rigid assembly. Cabi-
net shall be coated with baked on powder paint which,
when subject to ASTM B117, 500 hour, 5% salt spray
test, yields minimum ASTM 1654 rating of “6”. The unit
shall be insulated with 1-1/2,” 1 pound fiberglass insu-
lation between the two sheet metal skins. Insulation shall
meet NFPA-90A regulations for smoke and flame
spread ratings. Single-wall units, or foil-faced insula-
tion in the air stream shall be not acceptable.
The cabinet corner post and the intermediate side sup-
ports shall be a minimum of 16-gauge steel. All access
doors shall be a minimum of 18 gauge on the exterior
surfaces, and 20 gauge on the interior. Interior floor
panels shall be 18 gauge.
All serviceable sections shall have hinged access doors
with latches on both sides of the unit. All access doors
shall be constructed of 20-gauge steel on the outside,
with 24 gauge on the inside. Each door shall seal against
PVC gaskets to prevent air and water leakage.
The roof shall be double wall, with 18 gauge on the
external surface and 24 gauge on the interior. The roof
shall be formed with a 45 degree “drip lip” overhanging
the side walls to prevent precipitation drainage from
streaming down the side of the unit. Roof sections shall
be connected together via integral channels fastened
with screws and sealed with gasketing. Each fastened
seam shall be further protected by a sheet metal chan-
nel covering the full length of the gasket surface, mak-
ing a completely water tight seal.
SUPPLY AIR SYSTEM
Supply Air Fan
Fans shall be centrifugal type, statically and dynami-
cally balanced in the factory. Fan wheels shall be de-
signed for continuous operation at the maximum rate
of fan speed and motor HP. Fans shall be double-width,
double-inlet with forward curved blades.
The fan and motor assembly shall be mounted on a
common base to allow consistent belt tension with no
relative motion between the fan and motor shafts. The
entire assembly shall be isolated from the unit base
with 1" deflection springs. The fan discharge shall be
connected to the cabinet through a reinforced neoprene
flexible connection to eliminate vibration transmission
from the fan to the unit casing.
BEARINGS AND DRIVES
Bearings shall be self-aligning pillow-block re-greasable
ball bearings with an average life expectancy L10 of
40,000 hours. Grease fittings shall be accessible
through access doors.
Fan motors shall be NEMA designed, Standard effi-
ciency ball bearing type with electrical characteristics
and horsepower as specified. Motors shall be 1750
RPM, open drip proof type. The motor shall be located
within the unit on an adjustable, heavy steel base.