Monthly Archives: March 2012

There are a lot of people who like to ride bicycles in Southern Arizona where the weather is often pleasant enough that they can ride almost year-round. And, there are a lot of people who drive cars and trucks (let’s just say vehicles)  in Southern Arizona who don’t like to encounter bicycle riders on the roadways. Unfortunately, those encounters are sometimes dangerous for the bicycle riders, and, sometimes, there are even confrontations between the bicycle riders and the vehicle drivers.

From the perspective of the bicycle riders, this shouldn’t happen. After all, their philosophy is that all they want from vehicle drivers is to share the road. There are even signs on the rural highways frequented by bicycle riders that have a picture of a bicycle on them, along with the phrase “Share The Road”.

I saw several of them on the rural road I drove along earlier today, and it occurred to me that these signs could be the reason that vehicle drivers are not happy about their encounters with bicycles on these two-lane highways. It occurred to me that the vehicle drivers don’t think that the “Share The Road” signs are really telling the truth, the whole truth, and nothing but the truth. It occurred to me that from the perspective of the vehicle driver, they’re not really “sharing” the road as much as they are “yielding” the road to bicycles.

Consider it from this perspective:

…A person is driving a vehicle down a rural roadway, on which the speed limit is 55 MPH.

…They find themselves coming up on a person riding a bicycle, which is not capable of achieving the 55 MPH speed limit.

…At the same moment, another vehicle is coming from the opposite direction in the other lane.

When this happens, the person driving the vehicle that has come up behind the bicycle, naturally has to avoid two things: 1. Running into the bicycle, and, 2. Moving into the other lane which would risk a head-on collision, or force the oncoming vehicle to go off the road. It’s possible that, instinctively, from the vehicle driver’s perspective, this is not “sharing” the road with the bicycle, but rather “yielding” to the bicycle. Which means that they (again instinctively, and not consciously) don’t think that the signs with the pictures are telling the truth,  the whole truth, and nothing but the truth.

Which means that there is a simple solution to this problem. Replace the “share the road” signs with signs that read “Yield To Bicycles”, a sign that will tell the truth, the whole truth, and nothing but the truth. And when vehicle driver’s see a “Yield To Bicycles” sign, and they encounter a bicycle on the roadway in the situation described above, they’ll instinctively know that they’re being told truthfully what is necessary, and they’ll be willing to do it. No more dangerous pass-by’s for bicycle riders, no more confrontations that are a result of a misunderstanding between the people that ride the bicycles and the people that drive the vehicles.

And, what if we were to apply this idea, not to bicycle riders and vehicle drivers, but to technicians and customers?

Is it possible that there are times when a technician is, from their perspective, communicating correctly with a customer, but there is, in reality, a misunderstanding from the perspective of the customer, making them wonder if they are being told the truth, the whole truth, and nothing but the truth?

As a technical professional, it’s our job to be sure that the customer has a complete understanding of the service we’ve performed for them, why it costs what it costs, and why we were sure it had to be done the way we did it. Always make sure that the customer is certain that we’re telling them the truth, the whole truth, and nothing but the truth, even if it means you have to explain the same thing to them in more than one way, and ask them several times if they have any questions you can answer for them.

Until next week…..

Learn from yesterday….Live for today….Look forward to tomorrow


As we complete our discussion on the fundamentals of Carbon Monoxide in this segment, I want to point out that two other symptoms of low-level CO poisoning are headaches and confusion. And one example of these specific symptoms involves this case study of a situation involving an elderly resident. The factors in this case are as follows:

Complaint: Frequent headaches.

Observation: Elderly resident seems to be confused and disorientated at times, lucid at other times.

Building Type: New, energy efficient construction, one-bedroom, elderly housing unit.

HVACR Equipment: Heat pump.

Kitchen Equipment: Electric range and standard exhaust vent system.

Water Heater. Natural gas, in laundry room adjacent to kitchen.

Fuel-Burning Equipment Operation and Ambient CO Measurements: An initial test showed normal draft of water heater and no CO emissions from the vent into the living space. However, a secondary test with vent fan operating in the kitchen showed a significant loss of negative draft pressure in the water heater vent, resulting in a carbon monoxide spill, emanating from the laundry room.

To put it simply: Complaints from a resident of this specific type of housing unit could have easily been written off as a condition and/or other health issue related to advancing age. Instead, the actual source of the problem was insufficient combustion relief in the laundry room that wouldn’t allow the water heater to vent properly in the event of a drop in building pressure in the room adjoining the combustion appliance zone.

The two instruments necessary to accomplish the test procedures in this case study were a draft gauge, used for measuring the pressure in the vent system, and a device designed to measure ambient levels of CO in a building.

In addition to accomplishing ambient measurements of CO in a living space to determine if fuel-burning appliances are operating properly in regard the vent system as mentioned in the case study above, a more advanced level of testing, known as a combustion analysis, can be accomplished to further evaluate the operation of equipment. This process requires a more sophisticated device, one that is capable of  evaluating the overall operation of the burners. In the example in Figure Two, we’re showing the factors that are evaluated when device that is capable of these simultaneous measurements is employed.

Figure Two

The equipment in this case is forced-air gas furnace with an 80% efficiency rating, and the procedure for obtaining these measurements is to drill a hole in the equipment vent (re-seal it with a high temperature silicone once testing is completed) and inserting the instrument probe into the opening. While this analysis print-out is showing the measurement several factors, note the two listings that are highlighted, the Oxygen level shown at 10% and the Carbon Dioxide measurement shown at 6.1%.

In this specific instance, a furnace of this type should show an Oxygen reading of 6 to 8 percent, and a Carbon Dioxide measurement between 8.25 and 9.5 percent. When comparing data regarding what the measurements should be, and the actual measurements recorded by the device, we know that the Oxygen level is higher than it should be and the Carbon Dioxide level is lower than it should be. This means that the furnace is not operating properly, with the burner is functioning in a condition known as under-firing. What this analysis leads us to is a diagnosis that the fuel pressure being supplied to the burners in this equipment is lower than it should be, and an adjustment is necessary to bring the pressure up to a proper level. This will ensure the correct ratio of fuel to air, and the proper operation of the burner.

In addition to vented appliances, non-vented appliances such as the gas range shown in Figure Three, could also be responsible for a CO spill in a building if the burners are not operating properly. To be certain that a residence is not experiencing excessive CO levels and that fuel-burning equipment is operating properly, ambient measurements in the building, and a combustion analysis of vented equipment, are necessary.

Figure Three

Until Next Week….

Learn from yesterday….Live for today……Look forward to tomorrow.



Picking up where we left off last week, another factor to keep in mind about cabon monoxide generating equipment and draft measurements is that the water column-inch measurement scale we mentioned is a very fine measurement of pressure. One PSI is equal to 27.70 inches of water column, and the draft measurements we mentioned relative to a natural draft appliance are a fraction of a water column inch. The bottom line regarding the proper operation of atmospheric draft equipment such as a water heater or natural draft furnace is that if a given CFM of air is removed from the building due to the conditions mentioned above, then some method of allowing the re-entry of the same amount of air into the building must exist.

An important factor to understand about this situation is that it can be easily written off as extremely rare because the general belief is that if it did happen, somebody would be killed by the CO spill, or at least become gravely ill and wind up in the hospital. As I said last week though, there’s such a thing as low-level CO poisoning, which doesn’t always result in an emergency trip to the hospital. Here are some numbers for you to consider about CO levels in a building, measured in what is referred to as an ambient measurement in PPM (Parts Per Million):

009 PPM: Maximum allowable concentration for continuous 24-hour exposure. In an outdoor situation, this standard is often exceeded in urban areas due to auto exhaust.

10 to 35 PPM: Occupants should be advised of a potential health hazard, particularly to infants, small children, elderly people, and persons with respiratory or heart problems.

35 PPM: Common action level for fire department and other emergency personnel to use self-contained breathing apparatus.

50 PPM: OSHA requirement for maximum allowable concentration for workers continuous exposure in an 8-hour period.

70 PPM: Concentration required for UL2034 alarms to sound when CO at this level is present for as long as 60 minutes.

36 to 99 PPM: Medical alert. Ventilation required.

100 to 200 PPM: Dangerous, a commonly accepted building evacuation standard.

150 PPM: Concentration required for some UL2034 alarms to sound when CO at this level is present for 10 minutes.

220+ PPM: Extremely dangerous.

When you consider the listings above, you immediately recognize a possible health hazard for many people. Note that many alarms do not sound until the CO level in the building is beyond what is known to be a health hazard for the elderly, those with health issues, or children. A fundamental way to consider CO alarms is that they are designed to go off in the event that the carbon monoxide level in the building reaches a point where it would be hazardous for a healthy adult male….based on requirements that were initiated via testing and research involving military personnel.

Another factor to consider regarding a CO alarm is when it was purchased. For the most part, the sensor in the alarm that reacts to the carbon monoxide has a shelf life of approximately two years from the date of manufacture. And most consumers are not aware of this, thinking that if they faithfully replace the battery and press the TEST button on their five-year-old alarm, initiating an audible warning, that they will be protected against a CO spill. The simplest way to explain this process to a customer is that then they press the button, what they’re testing is a button and a power supply only, not the ability of the sensor to function. The only way to properly assess the function of a CO alarm is to use a test kit that includes a plastic bag to surround the alarm and an aerosol container of a material that, once sprayed into the isolated area, will cause the sensor to react.

The technician advising a customer about CO should also be aware of other facts related to the dangers of carbon monoxide. Symptoms are often written off as being other health issues, such as the flu. In one hospital study of 100 patients who requested treatment for what they thought was the flu, 24 were found to be affected by low-level carbon monoxide poisoning. Health care providers, if they are going to confirm carbon monoxide poisoning, must accomplish a carboxyhemoglobin test, which requires taking a blood sample for analysis.

Until next week…

Learn from yesterday….Live for today….Look forward to tomorrow


It’s a tradition in the appliance and HVACR service industry that there will be a high level of concern about carbon monoxide in the fall, with technicians fielding questions from the customers about alarms and requests for testing equipment for proper operation. And, as the winter wears on, people tend to forget about the concerns they had at the beginning of the season because their assumption is that the threat of a  (Carbon Monoxide, so identified with the chemical symbol “CO” since it is a product of carbon and oxygen) spill has been dealt with for another year, and they don’t need to be worried about it until the next heating season rolls around. The reason this is true is because most people equate a CO spill into a living space with a serious incident; the kind of thing you hear about on a news report about a furnace problem that results in someone getting killed.

However, from a technician’s perspective, there’s much more to the issue of CO safety, equipment operation and the alarms that are supposed to warn of an incident. One issue is what is commonly referred to as low-level carbon monoxide poisoning, which can be occurring in a residence or commercial building on an intermittent basis at any time of the year, and it goes largely unnoticed even though has an effect on the health of the building occupants. Consider the simplified building in Figure One.

Figure One

The first thing to understand about this building is that its tight construction, along with several other factors, is that it’s possible to create a slightly negative pressure in the structure. Hence, the collapsed look of the house. And, in this typical home, the gas furnace, which is a natural draft type, the and water heater  (which will almost certainly always be natural draft equipment), are in the basement along with the clothes dryer. On the main floor, there’s a range vent in the kitchen and a vent in the bathroom, and there’s a fireplace. And there is an attic vent system. Note what is happening to the vent system on the water heater and the furnace.

Both of these items, since they are connected to a common vent system, rely on a slightly negative pressure…likely in the range of -.02 to -.06 on water column-inch scale… to vent the by-products of combustion from the building. And when the pressure in the building is unaffected, or if there is either plenty of infiltration due to less-than-tight construction or a combustion relief system, this atmospheric vent system on these two appliances will operate as designed. However, in the event that the building pressure drops to a negative level, the vent system will back-draft, a condition we’re showing in our illustration.

One of the reasons for this condition is the vent on the clothes dryer, which expels approximately 150 CFM from the living space. Next is the kitchen vent, which, depending on the model, can send up to 250 CFM of air out of the building. In the bathroom on the second floor, the fan there, which is designed to vent moisture and odors, will also expel another 50 (or possibly more, depending on the design of the fan) CFM out of the building.

When you add the possibility that there could be infiltration from the living space up into the attic, and a possible open chimney damper on the fireplace, some, or all these factors, could create a negative pressure that allows for the back-drafting of any natural draft appliance. And, since carbon monoxide has a specific gravity of 0.98, meaning it is slightly lighter than air, an open basement door or infiltration from the basement to the living space will allow the CO to rise. And, since CO is so close to the weight of air, it will stratify and linger in the building.

Until next week….

Learn from yesterday….Live for today…..Look forward to tomorrow


“I used to do A/C work.”

“Yeah, I was in air conditioning for a while.”

“I went to HVAC school and worked at it some, but then I switched jobs.”

Have you ever been in a conversation with somebody who said something similar to the above? I have. And, I know that when I hear something like “I used to be in the HVACR business,” there’s a 99% chance that the person who is telling me that was never a member of a trade association nor did they ever invest any of their own time and money in learning more during the time they were ‘in the business’. And my reasoning behind that belief is simple. If a technical professional is serious (and I mean serious) about their craft, they will either become a member of an appropriate trade association and/or avail themselves of any opportunity for continuing education so they can take advantage of those available opportunities to continously improve, learn, and develop as the professional they are, even if it means investing some of their own money and attending training while they are “off the clock”.

And, it’s my opinion that if they aren’t serious about their craft, they won’t.

The unfortunate thing about the heating, air conditioning and refrigeration business is that, like any business, there are some people working within it who just consider what they do as a “job” and not a career. And all they focus on  is that whatever-amount-per-hour that they’re being paid while they watch the clock as closely as possible and keep score so  they’re sure they’re not ‘being screwed’ by “The Man” (whoever or whatever that really is).

Well, if you’re not of the ilk mentioned above, I have a suggestion for you. Join RSES. Yes, the price of membership is around $100 per year, but it’s money well-spent. As a member, you get a subscription to their monthly magazine, RSES Journal, which keeps you abreast of what’s new in the industry, and informed about the business you’ve chosen to be part of, while learning new things you need to know in order to stay up-to-date and hone your skills as an HVACR professional. And, you can stay connected with others in your craft by attending your local chapter’s monthly meeting. And, on top of all that, this trade association offers training (their motto is that they are “The HVACR Training Authority”) via workshops, conferences, and training materials in their on-line store. RSES is also active in providing preparation and study materials for NATE certifcation testing, and administering the exams.

To be sure, there are other trade associations related to the HVACR industry that also provide training opportunities and other benefits to HVAC contractors and business owners. In my opinion, though, RSES does the best job in regard to providing technical training for the people who are actually out there turning wrenches. And I recommend you make the very small investment in membership and avail yourself of the benefits being a member provides.

Unitl next week….

Learn from yesterday…..Live for today…..Look forward to tomorrow



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