Application Data
UNIT LOCATION
The YCUL Condensing Units are designed for outdoor installation. 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 struc- tures where normal operating sounds may be objec- tionable.
3.Installation sites may be either on a roof, or at ground level. (See FOUNDATION.)
4.The condenser fans are the
5.When it is desirable to surround the unit(s), it is rec- ommended 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- SIONS. When the available space is less, the unit(s) must be equipped with the discharge pressure trans- ducer 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 founda- tion, 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 structural 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 use of
GROUND LEVEL INSTALLATIONS – It is important that the units be installed on a substantial base that will not settle, causing strain on the refrigerant lines and resulting in possible leaks. A
Mounting holes (11/16" diameter) are provided in the steel channel for bolting the unit to its foundation. See
DIMENSIONS.
For ground level installations, precautions should be taken to protect the unit from tampering by or injury to unauthorized persons. Screws on access panels will pre- vent casual tampering; however, further safety precau- tions, such as unit enclosure options, a
REFRIGERANT PIPING
When sizing refrigerant pipe for split system air condi- tioning, consideration must be given to the: (1) Suction line pressure drop due to friction, (2) Liquid line pres- sure 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 psi, some refrigerant will flash before it reaches the thermal expansion valve.
All horizontal suction lines should be pitched at least 1/4 inch 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 should have a ‘P’ trap at the bottom and the top to facilitate oil return. Suction lines with a vertical rise exceeding 25 feet should be trapped every 15 feet 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.
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