Application Data - York YLUA Series Operation Manual

Application Data

UNIT LOCATION
The YLUA Condensing Units are designed for outdoor in-
stallation. When selecting a site for installation, be guided
by the following conditions:
1. For outdoor locations of the unit, select a place having
an adequate supply of fresh air for the condenser.
2. Avoid locations beneath windows or between
structures where normal operating sounds may be
objection able.
3. Installation sites may be either on a roof, or at ground
level. (See FOUNDATION, below.)
4. The condenser fans are the propeller-type, and are
not recommended for use with duct work in the con-
denser air stream.
5. When it is desirable to surround the unit(s), it is
recom mended that the screening be able to pass the
required chiller CFM without exceeding 0.1" of water
external static pressure.
6. Protection against corrosive environments is available
by supplying the units with either copper fin, cured
phenolic, or epoxy coating on the condenser coils.
The phenolic or epoxy coils should be offered with
any units being installed at the seashore or where
salt spray may hit the unit.
In installations where winter operation is intended and
snow accumulations are expected, additional height must
be provided to ensure normal condenser air flow.
Recommended clearances for units are given in DIMEN-
SION DRAWINGS. When the available space is less,
the unit(s) must be equipped with the discharge pressure
transducer option to permit high pressure unloading in the
event that air recirculation were to occur.
FOUNDATION
The unit should be mounted on a flat and level foundation,
ground or roof, capable of supporting the entire operating
weight of the equipment. Operating weights are given in
the PHYSICAL DATA tables.
Roof Locations – Choose a spot with adequate struc tural
strength to safely support the entire weight of the unit and
service personnel. Care must be taken not to damage
the roof during installation. If the roof is "bonded", consult
the building contractor or architect for special installation
requirements. Roof installations should incorporate the
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use of spring-type isolators to minimize the transmission
of vibration into the building structure.
Ground Level Installations – It is important that the units
be installed on a substantial base that will not settle, caus-
ing strain on the refrigerant lines and resulting in possible
leaks. A one-piece concrete slab with footers extending
below the frost line is highly recommended, particularly in
areas where winters are long and very cold. Additionally,
the slab should not be tied to the main build ing foundation
as noises will telegraph.
Mounting holes (11/16" diameter) are provided in the steel
channel for bolting the unit to its foundation. See DIMEN-
SION DRAWINGS.
For ground level installations, precautions should be taken
to protect the unit from tampering by or injury to unau-
thorized persons. Screws on access panels will prevent
casual tampering; however, further safety precautions,
such as unit enclosure options, a fenced-in enclosure, or
locking devices on the panels may be advisable. Check
local authorities for safety regulations.
REFRIGERANT PIPING
When sizing refrigerant pipe for split system air condition-
ing, consideration must be given to the: (1) Suction line
pressure drop due to friction, (2) Liquid line pressure drop
due to friction, (3) Suction line velocity for oil return, and
(4) Liquid line pressure drop due to vertical rise. Refer to
DESIGN PARAMETERS for friction losses for both the
suction and liquid lines for the condensing unit.
On a system where the evaporator blower is located below
the condensing unit, the suction line must be sized for
both pressure drop and oil return.
When the condensing unit is located below the evapora-
tor blower, the liquid line must be designed for pressure
drop due to friction loss and vertical rise. If the pressure
drop due to vertical rise and friction loss exceeds 30 psig
(2.1 barg), some refrigerant will flash before it reaches
the thermal expansion valve.
All horizontal suction lines should be pitched at least 1/4
inch (6 mm) per foot in the direction of the refrigerant flow
to aid the return of oil to the compressor. All suction lines
with a vertical rise exceeding 3 feet (1 m) should have a
'P' trap at the bottom and the top to facilitate oil return.
Suction lines with a vertical rise exceeding 25 feet (7.6 m)
should be trapped every 15 feet (4.6 m) to provide drain
points for the oil when the circuit is deactivated. When
the circuit is reactivated, oil will return to the compressor
more quickly and in smaller slugs.
For more details, refer to ASHRAE Refrigeration Hand-
book, System Practices for Halocarbon Refrigerants.
FORM 150.63-EG4 (1012)
JOHNSON CONTROLS