SOW_Attachment_-_Annual_Start-up_and_Shutdown_Checklist.pdf

DFAS LIMESTONE CHILLER

SOW ATTACHMENT

(MODEL ALR150EY27)

START-UP AND SHUTDOWN

Pre Start-up

1. Open all electric disconnects and check all electric connections for tightness.

Check all compressor valve connections for tightness.

2. Inspect all water piping for flow direction and correct connections at the evaporator.

3. Verify thermostat water temperature sensor is installed in the leaving water line

(supply to building). On all ALR units the sensor well and sensor are factory mounted.

4. Check compressor oil level. The oil level should be visible in the oil sightglass.

5. Check voltage of the unit power supply and make certain voltage is within ±10% of nameplate rating.

6. Check unit power supply wiring for proper ampacity and a minimum insulation temperature of 75°C.

7. Verify all mechanical and electrical inspections have been completed according to local codes.

8. Verify all auxiliary control equipment is operative and an adequate cooling load is available.

9. Open compressor suction and discharge shutoff valves until backseated. Always replace valve seal caps.

10. Open control stop switch S1 (off) and place pumpdown switches PS1 and PS2 on

“manual pumpdown.” Turn on the main power and control disconnect switches.

This will energize crankcase heaters. Wait at last 12 hours before starting up unit.

11. Open all water flow valves and start the chilled water pump. Check all piping for leaks and vent the air from the evaporator as well as from the system piping. Flush the evaporator and system piping to obtain clean, noncorrosive water in the evaporator.

NOTE: If LWC1 is a Unit 33 Metasys control, the control must be energized before the chilled water flow switch is closed.

CAUTION

Most relays and terminals in the unit control center are energized with S1 and the control circuit disconnect on. Do not close S1 until start-up.

Start-up

1. Verify compressor suction and discharge shutoff valves are backseated. Always replace valve seal caps.

2. Open oil equalization line valve.

3. Open manual liquid line shutoff valve at the outlet of the condenser subcooler.

4. Set temperature controller LWC1 to the desired chilled water temperature. Set the control band.

5. Start auxiliary equipment by turning on the following:

a. Ambient thermostat and/or remote on/off switch

b. Chilled water pump

6. Verify pumpdown switches PS1 and PS2 are in “manual pumpdown” (open) position. If pressures on the low side of the system are above 60 psig (414 kPa), the unit will start and pump down.

7. After the compressor lockout timer TD1 has timed out, start the system by moving pumpdown switches PS1 and PS2 to “auto pumpdown” position.

8. After running the unit for a short time, check the following:

a. Oil level in each compressor crankcase

b. Rotation of fans

c. Flashing in refrigerant sightglass

9. Verify superheat temperature is at the factory setting of 8 to 12 degrees F (4.4 to

6.7 degrees C).

Sequence of Operation

The following sequence of operation is typical for ALR air-cooled water chiller, Models ALR 110E through ALR 185E. The sequence varies depending upon options.

Start-up

With the control circuit power on and the control stop switch S1 closed, 115V power is applied through the control circuit fuse F1 to the compressor crankcase heaters HTR1, HTR2, HTR3, and HTR4, the compressor motor protections MP1, MP2, MP3, and MP4, and the primary of the 24V control circuit transformer. The 24V transformer provides power to the contacts of the low pressure controls LP2 and LP2 and the compressor lockout timer TD1 and TD2.

When the remote time clock or manual shutdown switch turns on the chilled water pump, the flow switch closes and 115V power is applied to the relay contacts on the leaving water control LWC1. The unit will automatically operate in response to the LWC1 if the manual pumpdown switches PS1 and PS2 are closed (in the “auto” position); the compressor lockout time relays R5, R6, R7, and R8; and the freezestats FS1 and FS2, high pressure controls HP1 and HP2, and the compressor motor protectors MP1, MP2, MP3, and MP4 do not sense failure conditions.

On a call for cooling, the leaving water control LWC1 completes the circuit to the liquid line solenoid valve SV1 for refrigerant circuit #1, opening the valve and allowing refrigerant to flow through the expansion valve and into the evaporator. As the evaporator refrigerant pressure increases, the low pressure control LP1 closes. This energizes the compressor starting relay R9, starting the compressor via the compressor contractors M1 and M5. Closing the R9 contacts also energizes the condenser fan motor contacts M11 and M12 starting the fan motors.

As additional stages of cooling capacity are required, the leaving water control LWC1 energizes the liquid line solenoid valve SV2 of the refrigerant circuit #2. After the compressor sequencing time delay TD11 has closed, the same starting sequence is initiated in refrigerant circuit #2.

If still more cooling is required, the leaving water control will start the remaining compressors and then de-energize unloader solenoids until the capacity requirement is met.

Pumpdown

As the leaving water control is satisfied, it will unload the compressor(s) and then de-energize the liquid line solenoid valve(s) SV1 and SV2, causing the valve(s) to close.

When the compressor has pumped most of the refrigerant out of the evaporator and into the condenser, the low pressure control(s) LP1 and LP2 will open. If the refrigerant leaks into the low side causing the pressure to close the low pressure controls LP1 and LP2, the compressor will start after a two-hour time delay. For normal temperature controlled operation, the timer is bypassed and the compressor will start on a refrigerant pressure rise.

NOTE: Do not shut the unit down without going through the pumpdown cycle. Flow switch, time clock, and ambient lockout thermostat must be wired to allow pumpdown when unit is turned off.