Monthly Archives: August 2012
At first blush, it may seem odd to be discussing carbon monoxide on an HVACR-related blog in August, but I came across a discussion thread on the subject recently, and read about a 65-year-old couple who lived in a housing authority rental in Portsmouth, Virginia, and recently died of carbon monoxide poisoning….they were found dead in their apartment in late June….and I decided that I had to talk about it in this week’s post.
I’ve said before that when it comes to CO poisoning (the chemical designation for carbon monoxide is CO since it is a product of carbon and oxygen), many consumers don’t think about the possibility of it happening until they consider the heating equipment in their homes, and whether or not it’s safe to operate their gas or oil furnace through the heating season. And, when they call in a professional to check their furnace sometime in the fall, one of the things they sort of have an idea about is that a fuel-burning furnace has a heat exchanger that, if it’s cracked, can cause the deadly by-products of combustion to leak into their living space. But, as I’ve also said many times before, CO poisoning doesn’t happen only in the winter, and it’s not only related to the operation of a furnace.
A water heater that operates on natural gas or propane could be the source of carbon monoxide in a building, and one of the reasons it can occur is something that people often don’t think about; upgrading their home by making it more energy efficient. The reason this can happen is simple. Since a water heater employs a natural draft vent system that depends on a slightly negative pressure to expel carbon monoxide and the other by-products of combustion, making a building tighter could result in back-drafting, which causes causes the gases to spill back into the living space rather than being vented to the atmosphere. Non-vented appliances, such as gas ranges, are another source of dangerous CO levels in a building. If the burners are not properly adjusted and operating cleanly, they will emit higher-than-normal carbon monoxide.
Whatever the source, a CO alarm is supposed to protect the building inhabitants, but in the case of the people in Portsmouth, according to a news report, an investigation found that the alarm had been tampered with because there was no battery and wires had been cut. The report didn’t offer any details beyond that observation, but one has to wonder why the alarm had been purposely disabled. When it comes to CO alarms many people are surprised to find that the one they have in their home is useless for a variety of reasons. The first one is the age of the device. I have a standard over-the-counter alarm that I show at the beginning of our facility maintenance training workshops, and I tell attendees that although the alarm has never been out of the package, it is absolutely useless.
The reason? I bought it more than four years ago.
A CO alarm does what it does via a sensor that reacts to carbon monoxide, and in many cases, the shelf life of that sensor is approximately two years from the date of manufacture. A homeowner that isn’t aware of the fact that a CO alarm must be replaced regularly will often tell a technician that they are sure their alarm works because, they “change the battery every year and push the test button to make sure that the alarm goes off.”
That’s all well and good, but the fact of the matter is, pushing a test button only shows that the battery is not dead and that the alarm is being tested manually. The only way to check the sensor operation on a CO alarm is to employ a test kit consisting of a plastic bag that surrounds the alarm and an aerosol can of a chemical that, when sprayed into the bag, causes the alarm to sound.
Beyond the sensor life of a CO alarm, there is also its sensitivity to consider. In many cases, CO alarms are designed to sound only when the level of carbon monoxide in the building reaches a point where it would be harmful to a healthy adult male, which means that it provides practically no safety for women and children, infants, or the elderly, all of whom will be more adversely affected by lower levels of carbon monoxide.
As an HVACR technician it’s our responsibility to be aware of the limits of some CO alarms and conditions that can affect the proper operation of a vent system or a non-vented fuel-burning appliance.
Learn from yesterday….Live for today….Look forward to tomorrow
In a perfect HVACR world, all comfort cooling duct systems would be designed for maximum efficiency and minimal heat gain and installed properly so that objective would be achieved. But, as we all know ours is not by any means a perfect world. A duct system in a tract home, for example, is often far from perfect. And it’s not just because of the design of the duct system itself, or because the installation wasn’t done right. The design of the building is a factor. To make my point, I’ll use the example of a typical extended plenum supply duct system in which the main trunk is manufactured either from fibrous duct board or sheet metal, and the branches are flex duct.
It’s common to find this sort of design and use of materials in a home that employs truss roof construction that creates an ‘attic’ crawl space. And, temperatures in that space will be significantly higher than the outdoor ambient temperature, and fantastically higher than the temperature of the air being transported through the duct system. Not that the specific numbers are the most important thing to consider at this point in our discussion, but it’s not uncommon to find an attic temperature far beyond 100-degrees F, while, in fact the temperature of the air in the supply duct will often be in the mid 50s….at least that’s what it would be after leaving the indoor coil and just starting its journey to the supply registers.
But, imagine this: You decide to do a fundamental inspection on the duct system and the building described above, and as you enter the attic on a 95-degree outdoor ambient day, you look up and see the bottom side of the roof sheathing above you. No foam insulation sprayed on the plywood, just the sheathing. And, now imagine that you recall that the roofing on this building is the typical dark charcoal color shingles used on tract homes. And, of course, when you look down at the main trunk and the flex duct, you’ll note that it is resting on, or perhaps suspended just above, the correct amount of ceiling insulation.
Yes, a typical installation, with the ceiling insulation required by code, the main trunk properly constructed with a reducing plenum to promote the proper static pressure in the second and third segments, and the flex duct properly installed, tightly connected with nylon zip-type duct straps to the main trunk transitions and the boots for the supply registers, pulled tight with no extra ducting snaking around the crawl space or hanging awkwardly from a truss. An installation done correctly, according to design….and not working nearly as efficiently as it could.
The reason, of course, is the extreme temperature difference between the supply duct air and the crawl space. While the air may exit the coil at the design temperature when the outdoor temperature is relatively mild, you can bet that that the system won’t be able to perform as it should once the temperature rises. Consider this: Ductwork insulation may be rated as low as R-6 or even R-4, which means that the amount of inevitable heat gain that will result in, say, one branch of the system, means that the discharge air temperature from that register will be significantly higher than it needs to be in order to achieve the desired comfort level in that room. And, that will result in extended run cycles that affect equipment performance, and increase operating cost.
The solution to this type of performance problem isn’t rocket science. Foam insulation on the underside of the sheathing will bring the crawl space temperature down significantly, or adding extra insulation around all ‘exposed’ ductwork to increase the R-factor and reduce the amount of heat gain in the air supply system will also allow the equipment to do the job it is designed to do.
Learn From Yesterday….Live For Today….Look Foward To Tomorrow
Being up-to-date can mean different things. In the case of the HVACR technician who has a great deal of general training along with extensive work experience in troubleshooting refrigeration and air-conditioning systems, up-to-date can mean a short, one-hour, factory-provided training session on the latest version of ECM (Electronically Commutated Motor) and the newest, updated troubleshooting procedures that don’t apply to earlier versions of this type of motor but do, in fact, apply only to this newest product.
And, without that “up-to-date”, one-hour information session, that technician may be lost when encountering that particular motor, which could result in wasted time, a mis-diagnosis, unnecessary expense for the customer, stress for the technician, etc….
“Up-to-date” can also have a different meaning for somebody without the great deal of training along with extensive work experience as described above. It could mean that this particular technician needs either an overview or a review of the fundamental concpets of electrical troubleshooting, or the general test procedures related to a particular type of relay or control system, or, maybe the same level of information related to refrigeration and air flow systems.
And, that “up-to-date” information could have been published this year, last year, the year before that, yet another year before that, or even five years ago, and it it will be “up-to-date” because the fundamental concepts being taught were developed and understood early in the history of the development of HVACR (such as the physics that govern the ability of a refrigeration system to accmplish heat transfer or the concepts that explain how to trace an electrical circuit from source-to-source in order to isolate that circuit and then perform the appropriate component testing….providing one has an understanding of what ‘right is in the first place’….to determine through the process of systematic elimination whether that component or another one in the circuit is responsible for the failure of the equipment to operate), because it’s general, common-sense information that technicians need to know in order to do their job.
All of this simply means that technicians need to know if what they need is ‘up-to-date” specific, applying-only-to-a-particular-component information, or ‘up-to-date’ information on general principles that actually helps them do two things:
1. Develop their overall troubleshooting skills.
2. Be able to completely understand what’s being presented in the first ‘up-to-date session I mentioned at the beginning of this post.
Learn from yesterday….Live for today….Look forward to tomorrow
If you’re a product of the American education system (or just about any education system in the world) you took tests while you were in school. And, the scores you managed on those tests determined in a large part what your GPA (Grade Point Average) was, and, at the end of a semester, quarter, or academic year, you got your number….the one that showed how well, or how poor you were at taking tests. Oh, sure, there were other things that you accomplished that contributed to that number. Homework assignments that you completed successfully, for example, often contributed a given percentage to your number. Or, in some cases, there were other classroom assignments, or even ‘extra credit’ things that you could do in order to bring your number up high enough so you wouldn’t wind up having to repeat an entire grade because your test scores wouldn’t be good enough on their own to allow you to move on the next grade.
Ah, yes, tests…..when it comes to tests and test-taking, people fall into one of two categories: Either they are good at taking tests, or they’re not. There’s just not a lot of middle ground here.
The way an academic system works when it comes to tests, is that we’re supposed to gather as much information about the test as possible. And then we’re supposed to study that information (cram for an exam), try to memorize as much as possible, and then, on the day of the test, hopefully regurgitate as much as much of the information we gathered and crammed as possible, and answer a majority of the questions correctly so we’ll get a passing score. And, the kicker here is that once you’ve studied, crammed and regurgitated, that particular test is history and it’s time to move on to the next test.
No wonder some people don’t like to take tests.
When it comes to test-taking, people who handle it well are usually of one of two learning styles. Either they are dominantly visual or auditory learners, meaning they can learn a lot just by seeing, or by listening carefully, or by employing those two skills in combination. People who don’t handle test-taking well are often of a different learning style altogether. They’re considered to be kinesthetic learners, which means their dominant information processing characteristic that allows them to learn and figure things out is ‘feeling-based’….touching….holding…hands-on stuff. People who are visually or auditorially dominant tend to gravitate toward academic, business, or other related professions. People who are kinesthetic tend to wind up in professions where they “work with their hands”.
HVACR technicians “work with their hands”….but they also work with their head, which is what makes them a technician, and technicians simply have to face the fact that testing and certification is (and should be) part of their professional life. Is this always easy and pleasant? Certainly not. I’d be lying to you if I told you that the six HVACR industry certifications I’ve tested for over the years (in the areas of carbon monoxide and combustion analysis, air balancing, and heat pumps) was easy and pleasant. But, in the process, I learned something about the subjects I had to test on, and, in the end, it contributed to my competency.
And, competency is what we’re all striving for when we are professionals who are passionate and dedicated to our craft, no matter how the testing system looks to us. Here are three simple lines that I think technical professionals should live by as long as they decide to stay in a career such as ours:
Work with your hands; you are a mechanic.
Work with your hands and your head; you are a technician.
Work with your hands, your head, and your heart; you are an artist.
Artists are passionate about what they do, and while, yes, they do get paid for what they do, there’s more to their chosen craft than money. They do what they do because it feels right, and because it gives them a feeling of satisfaction that goes beyond receiving payment for what they do, then using that payment to cover their monetary obligations. And, if taking tests is part of what has to be done in order to be able to continue doing what they do, then, well, they figure out a way to get it done, whether they like that part of their career choice or not.
Learn from yesterday…..Live for today…..Look forward to tomorrow