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 Btu Buddy get together for lunch and talk about why high head pressure seems to drive up the power consumption of a compressor. Bob remarks that the problem “doesn’t seem to happen in the cooling season, only in the heating season. What is the difference and why is this happening?”
Bob is called to a new customer’s home with a 5-ton heat pump that is experiencing power bills that are considerably higher than the same months last year. Btu Buddy assists Bob in diagnosing the problem.
The dispatcher calls and tells Bob that yet another person is describing an unusual smell when the furnace runs for a long period of time. Bob talks to the homeowner, checks out the furnace, and finds that it is backdrafting slightly. With the help of Btu Buddy, he tracks down the draft problem.
Btu Buddy and Bob meet for lunch and Bob has a question about the last service call. The job involved replacing the single-wall flue pipe with double-wall pipe. “You said that we had some unfinished business about the service call yesterday, yet you said that the call was complete. What did you mean?”
Bob goes on a call to a house where the residents smell fumes when the furnace is running. He examines the flue connector from the furnace to the chimney and discovers it’s rusted to the point of falling apart. With the assistance of Btu Buddy, he replaces the single-wall vent pipe with a double-wall vent.
Bob had changed a compressor and was just
about ready to charge the system when a problem arose. He pulled a vacuum down to 500 microns but noticed a rise in the vacuum gauge to 1,000 microns. There was a leak and Btu Buddy assisted him in finding it.
Bob receives a call from the dispatcher to go to an office building that has a 100-ton system that is water-cooled. With the help of Btu Buddy, he finds that the water level in the cooling tower is low. They check the water fill circuit and discover a kink in the copper pipe.
The temperature is 102° outside. The complaint is from a car dealership. The showroom temperature is 85° and the dealer is having a big sale the next day. Bob finds the a/c unit is already doing all it can. Btu Buddy shows Bob some tricks to get more out of the system.
In this installment of the Btu Buddy series, Bob and Btu Buddy meet on another job that has a low charge. This unit has a thermostatic expansion valve (TXV). They determine the evaporator is starved for refrigerant and check to see why.
In this edition of the Btu Buddy series, Bob works on a system that is not working up to capacity. He finds the suction service port is leaking, repairs it, and tops off the charge.