Bob and Btu Buddy have gotten together for a review of their last service call, which involved a control system that Bob was not very familiar with - pneumatic controls. Bob asked, “Why would anyone want to use air as the power source to operate the controls for a building?”

Effective pump maintenance allows industrial plants and commercial facilities to keep pumps operating well, to detect problems in time to schedule repairs, and to avoid early pump failures. Regular maintenance also reveals deteriorations in efficiency and capacity, which can occur long before a pump fails.

The customer’s complaint on this call was an overall overheating of his building. The manager told Bob, “We arrived this morning and the entire building was hot and keeps getting hotter.” He led Bob to the basement where there was a boiler. Bob found that the system had pneumatic controls.

When the customer calls for service, he tells you that when things got very cold in the house, he disconnected the power supply to the unit, and then, after turning the 120-volt service switch back on, the operation seemed normal and the house got warm “for a day or so.” But the failure repeated.

Bob’s service call yesterday involved a leaking underground refrigerant piping system. Bob replaced the refrigerant lines, leak tested the lines, and left them yesterday afternoon under 150 psig of pressure. He has now returned to the job the next day to see if the pressure held and to check for moisture in the system.

Every environmentally conscious service technician should spend time learning how to check for refrigerant leaks in refrigeration and/or air conditioning systems. Ozone depletion, global warming, and the increasing price of refrigerants are forcing technicians to become better and more thorough leak detectors.

For several years, refrigerant retrofitting has been a common procedure for a lot of the commercial kitchen and restaurant equipment I work on, so I’ll go over some of the things I’ve learned that might help you save some time and money on your own retrofit projects.

Bob was called to a job that had a no cooling complaint. This was a new customer and Bob wanted it to be a good experience for the customer. It was a small stand-alone store building with a 3-ton cooling only unit. Bob determined this was a low charge problem. He installed his gauges and discovered the unit did not have any refrigerant in it.

In this troubleshooting situation, we have a customer who has called to say that their 12,000 Btu through-the-wall unit is “blowing cool air even though it’s set for heat.” The unit is a heat pump with a three-speed motor. It operates on 240 vac.

Although a capillary tube can become totally restricted, a far more common problem is when it becomes partially restricted, allowing some refrigerant to flow into the evaporator but not enough to satisfy the requirements of the system. This seemingly easy problem to diagnose is actually rather tricky at times.