A critical step in the installation of a built-up (field-piped) refrigeration system is the startup and commissioning of the equipment, which simply means verifying the operation of the system and its components. Although this seems obvious, it is a step that is occasionally skipped or done too quickly to be effective.
Many warranty issues could be avoided by taking the required time to accurately complete startup and commissioning. That is why on some larger HVACR systems, the equipment manufacturer may have one of their field technicians or an independent technician complete the system startup after installation.
When it comes to startup and commissioning procedures, always follow the recommendations of the equipment manufacturer. If these procedures are unavailable, here are some key points to follow:
- Verify that the system’s running suction pressure, discharge pressure, condenser subcooling, and evaporator superheat values are correct for the application. It is best practice to observe these values when the case temperature is within 5°F of its design value. If installing an outdoor air-cooled condenser in a low ambient, you may need to partially block the condenser’s airflow to get reasonable subcooling value.
- If the compressor has an oil level sight glass, the oil level should be inspected at startup and after the system has achieved a steady-state operation. Verify the oil level in the compressor sight glass is at an acceptable level — it should be at or slightly above the center of the sight glass.
- Check all electrical connections, making sure they are tight. Verify that the voltage supply is within ±10 percent of nameplate requirements and the compressor amperage is acceptable.
- Verify the system’s temperature controls are operating normally by cycling the system off and then back on. If the system uses a pumpdown solenoid valve, make sure the low-pressure switch is cycling the compressor off and back on at the right pressures.
- If it is a low temperature system, check the defrost system. Initiate a defrost cycle and verify it terminates properly.
- If the system uses a crankcase heater, verify it is operational.
- If the system utilizes a water-cooled condenser with a water-regulating valve, verify the valve shuts down properly when the system is cycled off.
- Check the operation of the system’s high-pressure safety (if used). On air-cooled systems, disconnect the fan motors or block the condenser inlet air. On water-cooled systems, shut off the water supply. Watch high-side pressure for its cutout point.
- Make sure the equipment refrigerant type is labeled properly.
To ensure a proper startup is performed, many companies require their technicians to fill out a form to verify the system is operating properly and that the technician has inspected the required items. Make sure to complete the form, and do not put in false information or “pencil whip” the form.
Taking the extra time during an installation to do a proper startup benefits everyone. The customer gets a properly installed system, and the contractor and equipment manufacturer reduce their warranty costs.
Publication date: 3/4/2019