Heatcraft Refrigeration Products 25000102 operation manual Leak Checking, Evacuation and Start-up

Parallel Compressor Systems

Leak Checking, Evacuation and Start-up

Warning: It is illegal to knowingly vent or discharge any CFC’s and HCFC’s to the atmosphere. ALL CFC’s and HCFC’s must be reclaimed or recycled.

Leak Check

1.To check the systems for leaks, leave all valves closed on suction, liquid and hot gas manifolds. The unit is shipped with a holding charge of dry nitrogen and should be leak free. Build up the pressure in each circuit to a maximum of 150 psig dry nitrogen and check each individual circuit.

2.After each circuit has been checked, open all valves to allow the pressure into the unit assembly. Check to be sure pressure is throughout the assembly. Check all connections and accessories for leaks.

Evacuation

1.After the system is leak checked, connect a good high vacuum pump with fresh oil to both the low and high side evacuation valves. Connections between the pump and evacuation valves should be made with copper tubing or high vacuum hose having a diameter of at least 3/8”. Evacuate the system to 1500 microns for the first evacuation.

2.After each evacuation, the vacuum should be broken by the introduction of refrigerant into the system. The refrigerant should be passed through a drier when breaking the vacuum until the pressure is brought up to 0 psig.

3.Between the first and second evacuation, the liquid filter driers and suction filters should be installed in each replaceable core shell.

4.A triple evacuation is recommended. The third and final evacuation should achieve a value of 500 microns or less. After this vacuum is reached, add as much refrigerant as possible into the receiver. Now the system is ready to be started.

Start-up

1.Set all pressure controls as recommended elsewhere in this manual. Recheck all service valves and shut-off valves to be sure they are open.

2.Check and be sure the condenser fan motors are running in the correct rotation.

3.All evaporator fan motors should be checked for proper rotation. The fans in low temperature boxes generally have a fan delay for defrost purposes that keep the fans from operating until the evaporator coil has reached a certain temperature. It will be necessary to jump-out the fan controls on freezer units to make them run through final charging and room temperature pull-down. The wiring diagram for the unit will have to be consulted to determine how to best force the fans to operate for this step.

4.With all compressor and control breakers and toggle switches turned off, apply power to the unit. If the unit is using a phase monitor, the green light must come on before going any further. (See instructions for phase protector elsewhere in this manual.) A red light indicates incorrect phasing or voltage. Check with a volt meter to see if correct voltage is connected to the unit. Correct the Power Supply before proceeding.

5.Turn on the circuit breaker for the control power. If an electronic control system is installed on the unit, it will initiate at this time. The Heatcraft preferred controller is manufactured by Computer Process Control (CPC). Review the manual for the controller supplied with the system.

6.Turn on circuit breakers to all compressors.The compressors can be started by turning on the compressor toggle switches. Likewise, each circuit control can be started by turning on the circuit toggle switch. It is recommended that one compressor at a time be started and checked before allowing them all to operate. It is also advisable to check one circuit at a time to be certain all components work when called upon and that the circuit wiring is correct.

7.When each circuit and compressor has been tested and the appropriate amount of refrigerant has been added for proper operation, allow the system to operate and pull- down the room/fixture temperatures.

8.Once the system is operating, set all regulating valves.

9.When the room and/or the fixture temperatures are at design, the expansion valves should be set. (See instructions elsewhere in this manual.)

10.Adjust the electronic or manual pressure controls as necessary to maintain proper pressures and temperatures.

11.Check the refrigerant level in the receiver. The minimum level that should be maintained is 20%.

12.All circuit defrost controls must be set and checked. Again, one circuit at a time should be tested.

13.Set condenser fan controls to maintain the proper discharge pressure.

14.All safety controls should be checked and verified. Check that the alarm circuitry is operating at this time.

15.Check the oil reservoir during the start-up and add oil as necessary. The oil level should be between the upper and lower reservoir sight glass. Do not add more than two gallons of oil to a system. If more oil is needed, recheck the piping as oil is not returning to the unit properly.

Parallel Compressor Systems Installation & Operations Manual, October 2004 17