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Table 4-6

20 Ton Standard Operating Pressure Curve (All Compressors and Condenser Fans "On")

COOLING CYCLE PRESSURE CURVE

(Based on Indoor Airflow of 400 CFM / Ton)

FULL LOAD

160

180

200

220

240

260

280

300

320

340

360

50 55 60 65 70 75 80 85 90 95 100

SUCTION PRESSURE, PSIG

DISCHARGE PRESSURE, PSIG

105 F OD Ambient

95 F OD Ambient

85 F OD Ambient

75 F OD Ambient

65 F OD Ambient

To Check Operating Pressures

1. Start the unit and allow the pressures to stabilize.

2. Measure the outdoor air dry bulb temperature (F)

entering the condenser coil.

3. Measure the discharge and suction pressure (psig)

next to the compressor.

4. Plot the outdoor dry bulb temperature and the

operating suction pressure (psig) onto the chart.

5. At the point of intersection, read to the left for the

discharge pressure. The measured discharge

pressure should be within ± 7 psig of the graph.

25 Ton Standard Operating Pressure Curve (All Compressors and Condenser Fans "On")