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Table 9: Piping and Electrical Connection Sizes |
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MODEL | PC090 |
| PC120 | PC180 | PD180 | PC240 |
| PD240 |
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No. Refrigeration Circuits | 1 |
| 1 | 1 | 2 | 1 |
| 2 |
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Suction Line OD (in.) | 1 1/8 |
| 1 3/8 | 1 5/8 | 1 3/8 | 1 5/8 |
| 1 3/8 |
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Liquid Line OD (in.) | 5/8 |
| 7/8 | 7/8 | 5/8 | 7/8 |
| 7/8 |
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Power Wiring Knockout | 1 3/8 |
| 1 3/8 | 1 3/8 | 1 3/8 | 1 3/8 |
| 1 3/8 |
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Control Wiring Knockout | 7/8 |
| 7/8 | 7/8 | 7/8 | 7/8 |
| 7/8 |
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Piping And Electrical Connections
Piping connections are made from the rear of 7.5 thru 12.5 Ton units and from the front of 15 thru 20 Ton units. Stubouts are provided on the suction and liquid line service valves. Piping can be routed to the unit from the left or right side.
Electrical connections for power and control wiring are made from the right or left side of the electrical control box. See Table 9 and Figures 7 and 8 for piping sizes and electrical knockout details.
Start-Up
Crankcase Heaters
The crankcase heaters must be energized at least 8 hours before starting the compressors. To energize the crankcase heaters, the main disconnect switch must be closed. During this 8 hour period, the system switch on the room thermostat must be “OFF” to prevent the compressor from starting. Make sure that the bottom of the compressor is warm to the touch to prove crankcase heater operation.
Do not attempt to start the compressor without at least 8 hours of crankcase heat or compressor damage can occur.
Pre-Start Check
Before starting the unit, complete the following check list:
1.Have sufficient clearances been provided?
2.Has all foreign matter been removed from the interior of the unit (tools, construction or shipping materials, etc.)?
3.Have the condenser fans been rotated manually to check for free rotation?
4.Are all wiring connections tight?
5.Does the available power supply agree with the nameplate data on the unit?
6.Is the control circuit transformer set for the proper voltage?
7.Have the fuses, disconnect switch and power wire been sized properly?
8.Are all compressor mounting bolts properly secured?
9.Are any refrigerant lines touching each other or any sheet metal surface? Rubbing due to vibration could cause a refrigerant leak.
10.Are there any visible signs of a refrigerant leak, such as oil residue?
11.Has the refrigeration system been leak checked, evacuated and had the correctly calculated charge weighted in?
12.Is any electrical wire laying against a hot refrigerant line?
Initial Start-Up
1.Supply power to the unit through the disconnect switch at least 8 hours prior to starting the compressor.
2.Move the system switch on the thermostat to the AUTO or COOL position.
3.Reduce the setting of the room thermostat to energize the compressor.
4.Check the operation of the evaporator unit per the manufacturer’s recommendations.
5.With an ammeter, check the compressor amps against the unit data plate.
6.Check for refrigerant leaks.
7.Check for any abnormal noises and/or vibrations, and make the necessary adjustments to correct fan blade(s) touching shroud, refrigerant lines hitting on sheet metal, etc.
8.After the unit has been operating for several minutes, shut off the main power supply at the disconnect switch and inspect all factory wiring connections and bolted surfaces for tightness.
Johnson Controls Unitary Products | 17 |
