Air conditioning system commissioning and startup is the process of inspecting a new air conditioning installation, and verifying that the new system is running properly and efficiently.

The inspecting technician will take a look at the ducting (if any), the wiring, and the conduit runs.

He’ll verify that the piping is the right size, and check on the pipe insulation and support. He’ll check how and where the unit was installed, he'll check the anchors and brackets, and he’ll verify that there’s good airflow around the unit.

He’ll check to make sure the fans run in the right direction, the supply voltages are correct, the safeties are properly adjusted, and the thermostat is working correctly.

After the technician has verified that the installation is satisfactory, the next step in the air conditioning system commissioning and startup procedure is to start the unit, finish charging it up if necessary, and then verify that it cools normally and efficiently.

If there is a charging chart on the unit, or charging information in the service literature, he’ll verify that the unit is charged to factory specifications.

If there is no factory charging information, he’ll charge to standard HVACR industry specifications.

He’ll write up an air conditioning system commissioning and startup report, and the owner should get a copy.

The report should include the installation evaluation and the operating characteristics of the system:

• head pressure;

• suction pressure;

• subcooling;

• superheat;

• amp draws of compressor and fan motors;

• temperature rise through the condenser coil;

• temperature drop through the evaporator coil;

• wet bulb and dry bulb temperature readings of the evaporator return and supply air; and

• the cfm of airflow through the supply registers.

This information will be valuable to technicians who work on the unit in the future. It provides a baseline snapshot of how the unit ran when it was new and running normally, and it can help identify future cooling capacity problems more quickly.

Because such information saves technicians time when performing service, it saves both the contractor and the customer money.

Also, some contractors require that a qualified technician must perform an air conditioning system commissioning and startup inspection to qualify the unit for warranty.

Publication date: 04/07/2008

The first Copeland Scroll® rolled off the production line in 1987, and the cooling industry was changed in a way that would benefit contractors and their customers in many, many ways. The prime benefits have been efficiency and product reliability.

Many features of the Scroll focus on preventing compressor failures, but the Scroll’s primary design also improves efficiency and reliability thanks to its classic, concentric compression scroll, in which one spiral-shaped part fits into another; the space between the two parts contains crescent-shaped gas pockets.

CLASSIC SCROLL OPERATION

In operation, one Scroll is fixed in place while the other orbits within the first. The refrigerant gas is drawn in by the movement and forced toward the center of the scroll through successively smaller pockets, thereby increasing the gas pressure until it reaches its maximum pressure. Then it’s released through a discharge port in the fixed scroll.

Copeland Scroll compressors are unique in the industry because they feature both axial and radial compliance in their design, whereas other scroll models utilize a mechanically fixed design and scroll tip seals.

Axial compliance refers to the ability of the scrolls to separate in the axial — or vertical — direction remaining in continuous contact around an axis, in all normal operating conditions, ensuring minimal leakage without the use of tip seals. Radial compliance refers to the ability of the scroll flanks to separate. These features of the Scroll design allow the compressor to be more tolerant of liquid refrigerant or debris than other technologies, making for a compressor that is extremely durable and reliable.

The combination of axial and radial compliance means that Scroll compressors actually “wear in” rather than wearing out. Continuous flank contact, maintained by centrifugal force, also minimizes gas leakage and maximizes efficiency of the compressor.

Next month: Tech Tips will begin examining the Scroll’s improved reliability through its oil control system.

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