For Technicians Only…
..and I should add, techs who are a little weak in diagnostics. We always credit experience for expertise in some skill, regardless of the skill. Experience has always been the best teacher whether you’re working with heat pumps or airplanes…but experience is a somewhat generalized term leaving the inexperienced individual with little assistance in improving his skills level. In preparing presentation material recently for some “Troubleshooting Heat Pumps” seminars, I came up with a better way (I believe) to illustrate just what experience teaches us, relative to troubleshooting.
It helps to understand the mentality needed for troubleshooting equipment as opposed to building equipment. Heat pump technology is a product of several sciences. But a heat pump unit is the application of those same sciences. And if the unit was designed and manufactured around the scientific principles, it will do what it’s supposed to do…the science is built-in at the factory. So, as technicians, we aren’t required to verify or confirm the science, just the designed operation. So…whether or not we really understand all the implications of the Second Law of Thermodynamics isn’t really an issue. The Second Law of Thermodynamics may explain in scientific terms how or why a heat pump can cool / heat the house, but it won’t tell you the filters are dirty…So just what is it we need to know in order to troubleshoot equipment? For lack of a better expression, I’m going to say, knowing how stuff works, or knowing what stuff is supposed to do. And then you can extend that definition a little and add, …and what it takes to make it do it.
As an illustration, the electricity / magnetism principles that explain why/how a motor “runs”, won’t really help you diagnose a motor that isn’t running…if it isn’t running, some of the science is obviously missing. And if it isn’t running, then it’s not doing what it’s supposed to do. If you know or can figure out what it takes to make it run, you can diagnose the failure….and what does it take to make it run, or do what it’s supposed to do? Voltage source? that’s a good place to start. Closed switch? yep. Unbroken wires/circuit connecting the voltage to the switch to the motor? absolutely. Decent bearings? a must. Good capacitor? of course.
So if you find a motor not doing what it’s supposed to do, now you know what items to test, check, etc., to determine why the motor isn’t doing what it’s supposed to do. Isn’t that far simpler than than trying to measure or analyze the magnetic fields? I would think so…
I believe you will eventually discover diagnostics is more about understanding what the engineers intended the equipment to do, than understanding the scientific principles behind just how it does it. So, when the situation has you stumped, think in terms of what the device, part or system is supposed to do and what might keep it from doing it. Some skill with that approach will help you get you through the service calls…
To Order:Click Here
December 5, 2008 at 7:58 pm
Brilliant blog! I’m just starting to wade through this stuff. Ended up here after looking for answers on diagnosing reversing valves.
I’m the engineer learning how to be the tech (geothermal) for the last 3 years and I find practical/applied stuff like this invaluable. Your strength is being able to recall the time when you didn’t understand the problem and relating to that person now trying to figure it out.
Keep it up.
February 25, 2009 at 10:38 pm
One of the things I’ve noticed is that people don’t take the time to learn “sequence of operation” What is the piece of equipment SUPPOSED to do? I think techs have a tendency to want to jump in and start condemning parts without having a real, working knowledge of how the system works.
The other thing i have come to realize is that mechanical systems are made by human engineers, and human engineers have a tendency to design things the same way- on known scientific principles, and some of these things just aren’t taught properly in schools. Combustion, pressure/ temperature, enthalpy, latent heat, etc.