Standard Direct Expansion (DX) Cooling System

Condensing Air: The ambient condensing air enters the condenser at ≈ 95ºF and leaves at ≈ 115ºF.

Compressor: Condenser Fans: Draw ambient Moves the air across the condensing coil. Discharge Line through the Condenser Coil: Rejects heat system. absorbed from the air along with the heat added to the system during the compression process.

Condenser Tubes Expansion Device: Causes Liquid Line expansion cooling by creating a HIGH SIDE pressure loss between the high and low side of the system. Sight Glass / Moisture Indicator: LOW SIDE Provides a view into the system. Indicator is green normally, yellow Evaporator Tubes when high in moisture.

Evaporator Coil: The evaporator coil transfers heat from the warm air Supply Air: Enters the evaporator Filter-Dryer: Removes to the cool refrigerant. coil warm and leaves cool. Design water, debris and other condition for outdoor air is 95ºF contaminants from the Suction Line dry bulb 75ºF wet bulb. Typical refrigerant. leaving air design condition is 55ºF dry bulb, 54ºF wet bulb.

SYSTEM TEMPERATURES AND PRESSURES Refrigerant State T, ºF R-410A, psig Superheat/Subcool LOAD CALCULATIONS

Low Pressure Saturated 45 131.1 Condenser Qout (Btu/hr) = 1.08 x SCFM x ∆ Temperature

Low Pressure Superheated 53 131.1 Superheat = T - Tsat = 53º - 45º = 8ºF Evaporator Qin (Btu/hr) = 4.5 x SCFM x ∆ High Pressure Gas 180 448.2 High Pressure Saturated 125 448.2 High Pressure Liquid 110 448.2 Subcool = T - T = 125º - 110º = 15ºF 00.TAP.NB003 R1 9-2010 RG sat Copyright © 2010 Greenheck Corp. Air Cooled Packaged Options

Hot Gas Bypass Hot Gas Reheat Digital Scroll Hot gas bypass consists of a pressure-operated Hot gas reheat includes a condenser coil (locatedCondenser in Digital scroll compressors adjust to the cooling Coil valve located on the discharge line and additional the supply airstream) and a modulating refrigerant demand by separating (engaging and disengaging) refrigerant piping from the valve to the evaporator valve to control the supply air temperature and the ’s scrolls. When the scrolls are (DX) coil. Hot refrigerant vapor enters the hot gas relative . separated, or disengaged, no thermodynamic bypass valve from the compressor and is routed to work is done on the refrigerant. The compressor Benefit: HotHot gas Gas Bypassreheat Line controls the supply air the DX coil inlet as suction line pressure decreases. temperature and relative humidity without the need resumes the normal cooling cycle when the scrolls Suction line pressure decreases as the cooling load for auxiliary post heat (i.e. an electric heater). Hot are engaged. Cycle times between the disengaged decreases (indicating a part-load condition). gas reheat is often referred as “free reheat” as and engaged states are varied by a controller and pressure valve to adjust the compressor output to Benefit: Prevents the DX coil from freezing and the refrigeration system needs to reject theEvaporator heat Coil meet the cooling demand. reduces compressor cycling at part-load conditions. absorbed Suctionby the Line refrigerant to the ambient air or Availability: Standard on all MPX, ERCH and VER supply air for proper operation. This configuration Benefit: Digital scrolls offer capacity control from models with packaged DX cooling. provides a means to provide dehumidified air 10 to 100% of the rated compressor capacity. This without overcooling the space. turndown provides leaving coil temperature control Availability: Optional on all MPX, ERCH and VER as precise as 0.5°F. Digital scrolls also save Condenser models. by eliminating hot gas bypass as the compressor Coil output can be adjusted to meet cooling demands at

Air Conditions after Reheat Coil part load conditions. 70ºF DB / 60ºF WB 56% Relative Humidity Availability: Optional on the MPX, ERCH, and VER

Hot Gas Bypass Line models (up to 30 tons).

Reheat Coil Evaporator Coil Air Conditions after Evaporator Coil Suction Line 55ºF DB / 54ºF WB 94% Relative Humidity

Models MPX ERCH VER Airflow Range Min. CFM 1,000 1,000 2,000 Max. CFM 10,000 10,000 10,000 Evaporator Coil Cooling Performance Air Conditions after Reheat5 - Coil 30 4 - 30 4 - 30 Cooling Capacity70ºF Range DB / 60ºF WB 56% Relative Humidity tons tons tons Hot Gas Bypass Std. Std. Std. Hot Gas Reheat Optional Optional Optional Digital Scroll Compressors Optional Optional Optional Additional Cooling Options   Water Source Reheat Coil  Air Conditions after Evaporator Coil Heating Options 55ºF DB / 54ºF WB Indirect Gas 94% Relative Humidity  Hot Water   Electric    Water Source Heat Pump 

Evaporator Coil