50DK Weathermaker II Rooftop Units VAV Cooling with Optional Electric Heat
20 to 27 Nominal Tons
Models 50DK are one-piece cooling/heating or cooling only units that are pre-wired and pre-charged with R-22 at the factory. The standard unit is factory assembled, rated in accordance with ARI standard 360, tested in accordance with UL standard 1995, and listed by ETL and CSA.
Features/Benefits
Design flexibility: Dedicated vertical supply/return unit is ideal for new construction. The low unit profile is maintained when the unit is installed on the accessory roof curb, which is approved by the National Roofing Contractors Association (NRCA).
Unit efficiency: Dual serviceable, semi-hermetic compressors on intertwined evaporator coil ensures excellent full and part-load efficiency with EERs (Energy Efficiency Ratio) to 9.7. Dual refrigerant circuits provide standby capability should one circuit require service.
Reliable 06D Carlyle compressors are proven performers. Variable air volume (VAV) units have a minimum of 5 stages of unloading. Optional hot gas bypass valve permits low-load operation of the refrigeration system. Optional integrated economizer permits free cooling and utilizes a solid-state enthalpy control. The economizer operates in conjunction with mechanical cooling when required and is factory installed for either vertical or horizontal operation. A field-installed differential enthalpy sensor is available as an accessory for even greater energy savings. The use of differential enthalpy allows the unit control to compare the enthalpy difference between return air and outside air to determine which is more economical to condition for enhanced energy savings. Single supply fan design reduces noise and vibration, and avoids problems related to parallel fan designs. Inlet guide vanes (option) are avail-able on VAV units for fan modulation. All associated controls are factory installed. Alternate size motors provide application flexibility. Optional high-efficiency motors increase unit efficiency.
Installation/serviceability: Small footprint requires less roof area and makes unit easier to rig. Low unit profile allows units to be mounted closer to edge of building while remaining out of public view. Up to 60% smaller volume than comparable units. Single-point electric connections are standard on all units, regardless of voltage or optional heater size. Electrical service access can be made through roof curb or side of unit. Hinged access panels are located so as to make it easy to reach standard serviceable components for maintenance. No fasteners need to be removed, which reduces servicing time and prevents roof leaks caused by discarded screws puncturing the roof.
Unit controls Variable volume units utilize a self-diagnostic microprocessor based control. The microprocessor monitors stages of cooling, morning warm-up cycle and unit safety controls. At start-up, the self-diagnostic test verifies component operation and calibration. Fault codes reduce service troubleshooting time and difficulty. Accessory space temperature reset prevents overcooling the space and maintains higher airflow to ensure adequate ventilation air to the space. It automatically resets the discharge air temperature up when space temperature reaches the field adjustable set point. Discharge air temperature resets up 3.3deg. F for every degree below set point in the space. Unit design is ETL (Electrical Testing Laboratory) and CSA (Canadian Standards Association) certified. When installed with the economizer and power exhaust option or accessory and field-supplied switches and wiring, units can be run in the building pressurization mode or the smoke purge mode. In the event of a fire or smoke condition, a zone can be pressurized to prevent smoke from entering the zone, or smoke can be exhausted from a zone.