Here are some tips for HVAC and plumbing systems maintenance in commercial buildings that will help mechanical contractors and their customers save time and money.

When multiple compressors are piped together with a common suction and discharge header - such as with the arrangement of a parallel rack configuration - oil return to each compressor is a major concern. Typical oil recirculation rates are dependent on three factors.

This article is part one of a two-part series on ice flake machine troubleshooting. This article will examine troubleshooting low and high water levels. Next month’s article will examine water impurities and mechanical problems.

Bob has gone on a service call where the customer is complaining that her house is not getting up to temperature. The house was heated with a heat pump with three stages of auxiliary strip heat. Bob removed the panel to the strip heat and found one of the units was not pulling current.

Bob got a call from the dispatcher to go to an office building that has a 3-ton heat pump compressor that has been shutting off after startup. The fan would continue to run. The building maintenance man said that he had observed the shutting down of the compressor several times.

The actual frequency and tasks performed will vary from system to system. However, here are some generic maintenance tasks which can be applied to many refrigeration systems. These tasks can be divided into two groups: one for maintaining the cabinet and one for maintaining the refrigeration system.

This article explores how a restricted metering device will affect system performance and efficiency. The system is a commercial refrigeration system with a TXV as the metering device. The refrigerant being used is HFC-134a. Very similar results will occur if an automatic expansion valve (AXV) is used.

This troubleshooting situation is a look ahead to the upcoming cooling season. Our customer has called to say that their heat pump “isn’t cooling at all,” and while the outdoor temperature is only in the mid 80’s, it’s quite uncomfortable in the house. You find that the underlying reason is that the compressor and outdoor fan motor aren’t operating.

The good idea of sealing up a building to make it energy efficient had some unwanted side-effects. Lack of circulation or the inability of a building to breathe compounded the high humidity problem. Fortunately, the HVAC trade has remained a leader in providing information, answers, and products to combat the humidity problem.

Bob got a call to go to a convention center where the air conditioning system was not working. It was a 75-ton unit with one compressor. The system was many years old, but had been functioning fine, until now. After checking out the unit, an ohm check showed 0 resistance to ground.