CO Scare

I think that warnings about common hazards can become so commonplace that we don’t pay enough attention to them. We need something to wake us up. This week I received a wake up call when one of my students showed up to class explaining that his entire family had been suffering from carbon monoxide poisoning. He had missed over a week of classes and had come by once to explain that everyone at his house was sick. His family physician suspected something was up after treating everyone in the family for symptoms that mimicked flu. The doctor confirmed that they were indeed all suffering from CO poisoning. A little investigation revealed that the vent for the furnace in the attic had never been connected. There was a vent pipe, but it ran to within a foot of the horizontal furnace and stopped. The furnace was changed when he purchased the house. He showed pictures of the furnace. It was a model that can be difficult to connect vent to because the vent comes through the front access panel. I imagine the installers did not have the right parts, left it for “later” and forgot about it. The HVAC/R contractor did not get a permit, so there was no county inspector to find the problem. The home inspector did not catch it, from the attic access the vent looks like it is connected. The student thought that he had combination smoke and CO alarms. Turns out, they were just smoke alarms. So an obvious safety hazard that is easily corrected went unnoticed until the weather turned cold. The good news is that nobody died, the house now has CO alarms, and the source of the problem was found and corrected. It is scary to think what the end result could have been if the problem had not been recognized or if the weather had stayed cold for a longer period of time.

More people are sickened or killed by carbon monoxide poisoning than any other type of poison. The Center for Disease Control and Prevention (CDC) reports that each year more than 500 people in the United States accidentally die from carbon monoxide.  An estimated 10,000 people in the U.S. are treated for CO poisoning in hospital emergency rooms annually.  It is believed that many more people suffering CO poisoning are misdiagnosed, or never seek medical care. This is because the symptoms of CO poisoning are very similar to influenza symptoms. One big difference is that influenza causes a fever and CO poisoning does not.

Carbon monoxide is an odorless, colorless gas that is highly poisonous. It is formed by the incomplete combustion of carbon based fuels, like natural gas, oil, coal, or wood.  Incomplete combustion can be caused by lack of oxygen, improper mixing of the fuel and oxygen, or too low a combustion temperature. A correctly adjusted gas or fuel oil flame should produce very low levels of CO. Ideally a correctly adjusted gas or oil flame should produce no CO, but realistically, most produce at least trace amounts. Solid fuels almost always produce large amounts of CO; that is why charcoal comes with a warning that it is not to be used inside.

HVAC/R technicians are in a position to help. We can make sure all combustion appliances in the home are burning correctly, insure there is enough combustion air for proper combustion and venting, and finally by making sure the vent system is adequate and working correctly.  For gas and oil furnaces also remember to inspect the heat exchanger for leaks. The heat exchanger separates the combustion products from the air circulating in the home. Although a defective or cracked heat exchanger can contribute to CO poisoning, more obvious problems are frequently to blame. Stopped vents, loose or leaky vents, and lack of combustion air are common causes of CO. While every technician should learn to look for conditions that can lead to problems, testing is required to verify that a system is operating at safe levels of CO and that there is no CO in the house. Every technician should have an accurate CO tester. Household alarms are not a substitute. While every house with gas or oil appliances certainly should have CO alarms, they are not a replacement for an accurate tool for diagnosis.  I highly recommend a seminar done by Bob Dwyer for COSA (Carbon Monoxide Safety Organization) Make sure and take advantage of the opportunity if you have a chance to attend one of his CO Safety Seminars.

There are many units in Fundamentals of HVAC/R to help explain how to achieve safe, efficient combustion for gas and oil furnaces, including

Unit 37 Gas Fired Heating Systems

Unit 38 Warm Air Furnaces

Unit 40 Gas Furnace Installation, Startup, Checkout, and Operation

Unit 41 Troubleshooting Gas Furnaces

Unit 42 Oil Fired Heating Systems

Unit 43 Oil Furnace and Boiler Service

Unit 44 Residential Oil Heating Installation

Unit 45 Troubleshooting Oil Heating Systems

There are many good web sites for more research on carbon monoxide poisoning. A few are listed below.

http://www.bbc.co.uk/health/conditions/carbonmonoxide1.shtml

http://www.cosafety.org

Speed Up Your Service Calls

HVAC/R Technicians are under a lot of pressure to work quickly. The customer wants the problem fixed now. In the customer’s mind, the problem is fixed when the technician answers the door. If it were only that easy! The company also wants the technician to work quickly because time is money. The technician’s significant other wants the technician to work quickly and get home on time. Today people are so accustomed to downloading what they want, when they want it that they expect everything to come as easily and quickly. Life conspires to pressure the technician to repair HVAC/R equipment in the time it takes to download a movie. About the only way to actually accomplish this type of blitzkrieg service is to jump to conclusions and get lucky. It can you look brilliant to go right to the offending part on a hunch, replace it, and have the unit operating in minutes. But you can also look foolish if the unit quits operating before you get back to the shop. The customer now loses confidence in your ability. They can also feel cheated, suspecting that you did not check out the system thoroughly because you were there such a short time. From a practical standpoint, you have not saved any time if you have to return. In fact, your quickness has cost you time. I believe that being careful saves time in the long run and builds your reputation as well. Here are a few ideas on real time savings. Before you go to the service call, you should

Study! Your knowledge is the most powerful weapon in your troubleshooting arsenal. Read texts such as Fundamentals of HVAC/R, subscribe to service magazines such as the RSES Journal, enroll in classes at your local Technical College, join the local RSES chapter, and attend manufacturer’s service seminars. There are so many excellent educational opportunities for the HVAC/R industry that there really is no excuse to remain ignorant. Each hour you spend learning about your trade will save you many hours later on.

Build a good service library. You can’t keep an entire HVAC/R service library on your truck, but you can keep a few of your favorites. Don’t sell your HVAC/R tests – you can use them in the field. Service manuals and bulletins from equipment manufacturers are also very handy. If you can afford it, get a laptop with wifi internet. Most Companies now keep very complete service information on their web sites. 

Invest in quality tools. It always takes longer to do the job without the right tools. Don’t skimp on tools! Good quality tools that are made to perform the specific task at hand save you time. You can sometimes bang a motor shaft out of a blower wheel with a hammer and wood block, but it is so much faster and easier with a hub puller. And you will really cost yourself a lot of agravatino and time if you mushroom the shaft or warp the blower wheel.  

Next week I will discuss some tricks to speeding up the call after you arrive on the job.

Are Your Capacitors Stale?

A capacitor is a pretty simple device, basically a couple of rolled up sheets of aluminum foil or metalized film with paper or plastic between them. Any practicing service tech will tell you that service calls involving dead capacitors  are common. Technicians that have been around for a few decades will also tell you that capacitors die a lot more now than they did twenty years ago. This is because the newer capacitors use a different electrolyte. The electrolyte in the “good old style” capacitors was polychlorinated biphenyl, PCB. PCB causes cancer, so it is no longer used. The newer capacitors are smaller and less expensive than the older PCB capacitors, but they are not as robust. The two most common causes of capacitor death are heat and over voltage. However, there is another less known cause: old age. Many capacitors have a shelf life. I have seen shelf lives listed as little as one year. The oxides on the metalized film break down when the capacitor is not in use, weakening the capacitor. They tend to self-heal during use. That is why a capacitor that cannot sit on the shelf for longer than a couple of years can last for ten years in use. 

Always check the capacitance of any replacement capacitor with a capacitor tester or the capacitance scale on a digital multi-meter before using the capacitor. It may have already died of old age before you install it! Although a capacitor is a simple device, it is an extremely important part on most air conditioning systems. A bad capacitor can kill a system’s compressor. To protect your reputation and your customer’s equipment, only use capacitors that can pass the EIA-456 Highly Accelerated Life Test. The HALT test subjects a set of capacitors to 125 percent of their rated voltage and 10˚C above their rated temperature for 2,000 hours. For example, a capacitor that is rated at 5uf/440 vac, with an operating temperature of 70˚C, is tested at 550 vac and 80˚C for 2,000 hours. Two links for more detailed information on capacitors are  

Aerovox

Genteq

Determining which capacitors to stock on your truck is another problem. There are so many sizes of dual capacitors that it is nearly impossible to have all the necessary sizes. American Radionic, AMRAD, has a solution – a multiple capacitor with enough sizes to cover nearly any application. Better yet, they will send instructors sample capacitors to use in your lab. These are great for demonstrating the effect of connecting capacitors in series and parallel. Their web site is AMRAD

Fundamentals of HVAC/R has coverage of capacitors and their effect in circuits in  Unit 29 Electrical Power and Circuits, Unit 30 Electric Motors, Unit 33 Control Circuits, and Unit 83 Troubleshooting Refrigeration Systems. Unit 30 of MyHVACLAB has an interactive exercise on determining capacitance and a video on testing capacitors. Unit 83 has an interactive exercise on testing capacitors. 

Simplify Parallel Calculations

The total resistance in a parallel circuit is difficult to calculate because it cannot simply be added as in a series circuit. However, the total current flow in a parallel circuit is easy to calculate. It is simply the sum of the currents for all the individual loads. The famous parallel formula for resistances in parallel uses this concept.  Dividing the resistance of each load into 1 calculates the current draw for each load at 1 volt. Adding these fractions gives the total current draw of the entire circuit at 1 volt. Since resistance can be calculated by dividing current into voltage, dividing the total circuit current at 1 volt into 1 volt gives the total resistance. I confess that I have used and taught this formula for many years without knowing why it works. Once I understood the reason behind the formula, it seemed far more logical and less imposing.  Did you know that this works for any voltage you choose? We can use this to create a simpler parallel calculation. 


I find that many of today’s digital students struggle with the fractions, common denominators, and all the trappings that go with fractions. One solution is to convert the fractions to decimals. But the decimal numbers you get when dividing whole numbers into one are always several decimal places to the right of 0, causing another own sort of confusion. My suggestion is to choose a voltage at least equal to the highest resistance; preferably, twice the highest resistance. That way, all the answers will have at least one whole number. This not only makes the answers easier for the students to deal with, it makes the decimals to the right of 0 less significant, so lopping off a few won’t have as big an impact on the final answer.


 For example, with resistances of 15, 20, and 30 ohms choose 60 volts. Instead of trying to add 1/15  + 1/20 + 1/30  or their decimal equivalents, you are adding 60/30 + 60/20 + 60/15. Most people can add 2 + 3 + 4. Then, divide this total current, 9 amps, into the voltage we used, 60 volts, to get 6.6 ohms total resistance. OK, so I stacked the deck a bit. Another teacher’s trick – if you get to choose the questions, why not choose questions that make your life easier. After your students are adept at these “easy” problems, have them measure the resistance of some actual devices and do the calculations. This is where choosing to make the calculations easier really pays off. Anybody can make simple things difficult – the trick to teaching is to make difficult things simple. 

A Story of Personal Courage

Have you ever wondered how you would react in the face of personal tragedy? I have. When I read about tragedies in the paper or hear about them on the news, I find myself wondering “What if..?”  Fortunately, I have never found out. Soon the business of the day drowns out my musings, and I return to the business at hand. However, the closer to home the tragedy is, the more difficult it is to dismiss. 

Just before the start of this past summer quarter, my friend Bruce Arnold lost his 18 year old son Tyler in a motorcycle accident. Tyler was preparing to study air conditioning at Athens Tech and study with his dad. Bruce works in the field and takes classes in the evening. Bruce was so excited about his son going to school to study the trade he practices.

Only a parent can truly understand the feelings parents have for their children. You really cannot fathom how much you have been loved or how much of themselves your parents invest in you until you are a parent. When you are a teenager your parents unending questions about where you are going, what you are doing, and who you are going to be with are an incredible annoyance. Their interest in every detail of your mundane school day is perplexing. The reason is simple: parents have more interest in your safety and success than you do.  

Nobody celebrates your victories and accomplishments more than your parents. I have been teaching longer than most of my students have been alive, and I know that my mother is still my biggest booster. I have a 20 year old daughter and a 15 year old son, and I know I get far more excited about their accomplishments than my own. That is why I know there can be no greater pain than losing a child. Truthfully, I hope I never learn what it feels like.  

Bruce returned to school and completed his summer coursework. He explained that he felt compelled to come back to school because Tyler was so proud of his dad for going to college and so happy to be going himself. Many of Bruce’s friends counseled him to “put it behind him” and “go on with his life.” He couldn’t. Instead, he started a non-profit scholarship foundation in his son’s memory. He hired a lawyer to create the non-profit foundation, established a bank account for the foundation, started a web page to advertise his foundation, and is out personally raising money for the foundation. His goal is to raise money so other young men and women can realize their future, fulfilling their parent’s dreams. If you would like to learn more about Tyler or the scholarship foundation established in his name, go to http://www.thetylerbrucearnoldscholarshipfund.com/index.html   

Where Do YOU Belong?

You can tell a lot about someone by looking at who they hang with. The people and organizations you spend time with help form who you are and advertise to the world what you really think is important. I believe finding where you fit in is important. You may have heard people talk about networking: not a connection between machines, but a connection between people. Spending time with people that have similar interests and developing your common interests. Some of the benefits are obvious, like making valuable connections to folks that can help you. However, I believe part of the power of networking is that you find a group of people whom you enjoy being with. The truth is that most people are more inclined to put effort towards helping someone they know and like. Being with other people who share your interests makes all your activities more meaningful. Disneyworld is no fun by yourself; a big part of the magic in the magic kingdom comes from having fun with your family.

Joining an industry organization gives you immediate access to a group of people with similar interests. There are many groups organized around different aspects of the HVAC/R industry. There is a group for HVAC/R Technicians – RSES; a group for trades students – Skills USA; a group for Air Conditioning Contractors – ACCA; a group for HVAC/R Distributors – HARDI. If you teach HVAC/R you have some common interests with all of these groups. Every one supports HVAC/R education with resources and material. Trying to participate in all of these would probably not be possible for most of us, but joining and participating in one is doable for even the busiest folks. I suggest exploring what all of these groups have to offer, finding where you belong, and taking the plunge.

Each organization has an annual meeting where you can network with other HVAC/R folks, participate in training, see the latest in HVAC/R technology, and just have fun. If you have never been to a national HVAC/R convention, an opportunity coming up would be the National RSES Conference in Tucson, Arizona November 9 – 13.

Here is a partial list of HVAC/R organizations with links to their web sites where you can learn more about each one.

ACCA – Air Conditioning Contractors of America

ACTE – Association for Career and Technical Education

AHRI – Air Conditioning, Heating, and Refrigeration Institute

HARDI – Heating, Air Conditioning, and Refrigeration Distributors International

HRAI – Heating, Refrigeration, and Air Conditioning Institute

HVAC Excellence - Heating, Venitlating, and Air Conditioning Excellence

NAOHSM – National Association of Oil Heating Service Managers

PHCC – Plumbing, Heating and Cooling Council

RSES – Refrigeration Service Engineer’s Society

Skills USA

Understanding Relationships is Key

During the quiet times between quarters, our team members will often discuss what students are struggling with, what WE are struggling with, and look for ways to address these issues. The other day we were discussing why many students have such a difficult time learning how to identify the common, start, and run terminals on compressors. A few other problem areas came up – reading diagrams, superheat, subcooling, and system charge compared to superheat and subcooling. Then it struck me what all these things had in common – they are all relationships. You have to compare two or more pieces of information to arrive at a solution. Over my years of teaching, I have noticed that the more abstract a concept is, the more students struggle with it. Identifying components is usually not a problem because that is very concrete, just putting a name with something you can see and touch. Memorizing definitions is also fairly straightforward, even if it is not very exciting. Most students can give us a pretty good definition of superheat. But we lose many of them when they have to actually measure it on a unit. We lose even more when they have to use that measurement, compare it to the manufacturer’s specification, and determine if the charge is correct. I believe if you made a list of all the most important things students should learn to do before they leave you would find the most important skills involve understanding relationships. I don’t know of a sure fire way to teach relationships. I think that people who have a good mechanical aptitude readily see relationships. Students that have difficulty understanding relationships need explicit instructions and lots of practice. Teaching something that is “obvious” to you can be difficult because you have to deconstruct your thinking process so you can explain how you accomplish a task that you do innately. For example, suppose you had to teach someone how to use a screwdriver. Do you know exactly how you hold it? How do you get the screw started? What do you do after turning your wrist a quarter turn so that you can turn the screw some more? I have actually had to teach people how to use a screwdriver and it was one of the most difficult things I have ever taught because I really did not know how to explain it. Admittedly, the screwdriver example is extreme. However, the same type of deconstruction process can be used to explain more analytical processes like measuring superheat. My prescription for helping relationship challenged students is to:

Analyze the task in detail – leave nothing out and assume nothing.

Teach the students the process in explicit detail making sure they understand each step.

Practice, practice, practice!

Patience, patience, patience!

Remember, if all the students could do everything easily on their own they wouldn’t need you.