Anyone whose job involves servicing electric motors has encountered the problem of a missing nameplate. Other articles in the Motor Doctor series have covered ways of determining the specifications of a motor lacking the nameplate, but what if you are trying to figure out how to wire that motor?
Bob and Btu Buddy get together for breakfast to discuss their last service call, which concerned a compressor that had liquid refrigerant flooding back to it. Bob had asked a couple of questions while they were leaving the job. Btu Buddy then proceeds to answer Bob’s questions.
This time around our problem centers on a split-system air conditioner. The condensing unit is 240-volt, single-phase, and the indoor air handler (which our customer is able to tell us is “blowing warm air”) consists of a standard gas furnace and an A-coil housed above the furnace plenum.
This job is a three-story office building with an air handler on each floor with a refrigerant coil in each air handler. A 75-ton condensing unit serves the three 25-ton air coils. This is an old system that has still been doing a good job. The complaint is that the second floor unit is not holding the conditions that the thermostat is set for.
In steam systems that have not been maintained for three to five years, between 15 percent to 30 percent of the installed steam traps may have failed - thus allowing live steam to escape into the condensate return system. In systems with a regularly scheduled maintenance program, leaking traps should account for less than 5 percent of the trap population.
The day started with a call from the dispatcher who described a gas heat customer who had no heat. When Bob arrived, the first thing he noticed was that the furnace was cold. It had not been operating. At first, Bob thought that the thermostat was defective. Btu Buddy then arrived to clear up his confusion.
Your troubleshooting situation this time around relates to a walk-in refrigeration system in a busy restaurant that has experienced a compressor failure… specifically a mechanical failure. And it’s not the first time.
Bob and Btu Buddy have gotten together for coffee to discuss the previous service call and some of the questions about electric heating that came up. Btu Buddy said that they would talk about them one at a time, and probably other questions would come up.
When you improve chiller efficiency, you can have better control of the chiller and the air conditioning in the building, and the chiller will also last longer. The recommendations here are for centrifugal chillers. Several different methods are suggested.
A call has come in from a new customer that the system in a small office building is not heating properly. Bob finds the building has an electric heat furnace and, when he removes the panel, he is amazed at how many wires and terminals there are and starts to become confused. Btu Buddy arrives to assist him.