ACHRNEWS

Help prevent commercial startup failures

September 14, 2000
According to the National Weather Service, the continuing effects of La Niña mean drier and warmer-than-normal conditions are expected in southern sections from southern California eastward to the Carolinas.

But even routine summer weather can increase the risk of air conditioning breakdown, leading to costly repairs, business interruption, and lost customers. Hvac contractors that can help clients anticipate and prevent these risks will be providing a valuable service.

According to Dave Schraeder, assistant vice president at the Houston office of The Hartford Steam Boiler Inspection and Insurance Company, claim data shows that many failures take place at system start-up or early in the cooling season.

Most air conditioning problems result from electrical failure of the driving motor or mechanical parts breaking in the compressor.

“Air conditioning equipment can be very expensive to fix,” Schraeder said, “but that’s only part of the risk. The business interruption loss may exceed the property damage. Today, when you inconvenience customers, many of them go to your competition.”

Early season

According to Hartford Steam Boiler, the leading months for air conditioning breakdown claims, in dollar terms, are May and June. Approximately one-third of all failures occur between April and June.

Many of these failures could have been prevented with a thorough inspection at start-up and regular maintenance throughout the cooling season. Hartford Steam Boiler has prepared the following check list covering air conditioning system components and controls.

According to the company, these tips are intended to complement, not replace, the recommendations of equipment manufacturers.

Before startup

Compressors

  • Energize the crankcase heaters for at least eight hours before startup and before taking insulation resistance readings of hermetic motor windings.

  • Crankcase heaters should be left energized for the rest of the season so whenever the compressor is idle, the heater will prevent refrigerant migration to the crankcase.

  • Test the lubricating oil for color and acidity, and check crankcase oil level.

    Motors

  • Check the air passages of open motors for cleanliness and obstructions.

  • Check the condition of, and lubricate, bearings.

  • Take insulation resistance readings. If the readings indicate less than one megaohm resistance, don’t start the motor. Check the cause of the low resistance.

    Motor controls

  • Inspect starter contacts for deterioration from short cycling, arcing, or corrosion.

  • Check terminal connections for tightness.

  • Examine the overload protection for defects and proper size.

  • Check mechanical linkages for binding and excessive looseness.

  • Check timing devices for correct operating sequence.

    Operating and safety controls

  • Determine that the controls are properly calibrated and in working order, particularly thermostatic controls, oil pressure safety switches, and flow switches.

    Refrigerant circuits

  • Be sure the circuit is equipped with a moisture indicator and if moisture is indicated, install new liquid line filter-drier cores. Determine and correct the source of the moisture.

  • Check the expansion valve for proper operation and superheat settings over the full range of operation.

    Condensers and evaporators

  • Ensure that proper cleaning of heat transfer surfaces for the type of unit in use has been completed prior to operation.

  • For cooling towers, check the baffles for tightness and soundness. Clean the baffles, sump, and spray nozzles. Check the makeup water for proper operation.

    Pumps

  • Check the bearings, packings, shaft couplings, and seals. Lubricate bearings.

    Fans

  • Check for broken, cracked, bent, or loose blades.

  • Check hubs, fan shaft, and bearings.

  • Check the belt condition and belt tension.

  • Replace air filters.

    Piping

  • Check all piping supports for signs of distress.

  • Check for external damage and excessive vibration.


Insurance

Hartford Steam Boiler said it offers equipment breakdown coverage, which will pay to repair or replace insured air conditioning systems or components that suffer a covered loss. It also will pay for lost business income due to business interruption or loss of essential services.

According to the company, equipment breakdown insurance covers a range of machinery against losses resulting from mechanical breakdown, centrifugal force, and electrical malfunction.

The policies will pay to repair or replace refrigerant-bearing equipment, as well as the refrigerants themselves.

The startup checklist is posted on the company’s website at www.hsb.com/HSBhwa.htm.

For more information from Hartford Steam Boiler, call 860-722-1866.