Active in the HVACR industry since the 1950s, Bill Johnson graduated in gas fuel technology and refrigeration from the Southern Technical Institute, a branch of Georgia Tech (now known as Southern Polytechnic Institute). He taught HVAC classes at Coosa Valley Vocational & Technical Institute for four years. He moved on to become service manager for Layne Trane, Charlotte, N.C. He taught for 15 years at Central Piedmont Community College, part of this time as program director. He had his own business for five years doing installation and service work. Now retired, he is the author of Practical Heating Technology and Practical Cooling Technology, and continues as a co-author of Refrigeration & Air Conditioning Technology, seventh edition, all published by Delmar Cengage Learning. For more information, he can be reached at 704-968-0000 or thebillj1@gmail.com.
Btu Buddy Notebook is a collection of more than 50 service call scenarios in book form covering both cooling season and heating season troubleshooting. For more information and to purchase the book, visit the HVACR Industry Store.
Bob and Tim have gotten together for another informational session. Tim requested some extra after-hours training about heat pumps. In their last session, they talked about heat pump mechanical problems. This time they discuss electrical problems.
Bob and Tim were taking a break and Bob began explaining some of the tips that he has learned in servicing heat pumps. Bob said, “Let’s go over some of the service problems that you may have with a heat pump.”
The season was getting colder and heating calls were beginning to come in. Bob and Tim were riding to a large residence that had three heat pumps to provide heating and cooling for the structure and Tim asked a question, “Why are heat pumps so popular?”
Bob and Tim were doing a routine service contract call. They had fastened gauges to the compressor at the condensing unit and had a temperature lead fastened to the suction line at the evaporator coil. They were observing the pressures and temperatures and Tim said, “The suction pressure is not stable. Isn’t it supposed to be stable during a long running cycle?”
Bob and Tim have been tuning up a system with an orifice metering device for the correct evaporator charge, when Bob said, “There is another verse to tuning up a system, and it’s called subcooling.”
Bob and Tim were on their way to a no cooling call at a residence. They were pretty sure that it was a low refrigerant call. Bob said, “I hope that we can put the last lesson into practical practice. We have gone to a great deal of trouble to understand superheat.”
Bob and Tim were in the company conference room where Bob is set to give Tim some extra training at Tim’s suggestion. Bob said, “Tim, you asked for more explanation of what superheat is. This is not a very simple topic. It will take a couple of meetings to go into detail about it.”
Bob and Tim were driving to the job they left yesterday and talking over what needs to be done today, when Tim asked, “How are we going to move the condensing unit we disconnected to the new location so we can connect it to the system where we disconnected the defective condensing unit? You said you had a plan.”
Bob and Tim had left this residence a few days ago when they discovered that the four-way valve on the home’s heat pump was stuck in the cooling mode. They tried several things to get the valve to do its normal changeover to the heating mode and couldn’t get it to function. The valve would need to be replaced.
Bob and Tim were on their way to a service contract routine procedure when the dispatcher called and asked them to go to a residence that had no heat and had a very sick family member. They needed heat as quickly as possible.