The ‘Black Art’ of Engineering

In his response to my letter regarding his article on evaporative coolers (Letters, February 2007), Kenneth E. Robinson, CIH, made a statement that was quite thought-provoking. He wrote, “If the diagram provided by Mr. Surfas included long, complicated formulae, the high-tech crowd might be more accepting.”

Many of the articles written about what seem to be basic HVAC processes are overly dependent on mathematical formulae. An example would be the use of formulae to describe the three types of heat transfer involved in a direct-expansion cooling coil: nucleate boiling, conduction, and radiation. An entire page could be — and, I imagine, has been — filled with the equations leading to the derivation of the overall heat-transfer process. But why?

We engineers have made such a black art of what we do and been so reluctant to pass on information that a younger generation of engineers must go back and use the basic thermodynamic, heat transfer, and fluid flow they learned in college. We, the secretive engineers, have done just what the alchemists of medieval times did and created an atmosphere of mystery and suspicion around us. We have caused the new generation to “reinvent the wheel” on every project.

One of the main culprits is the lack of a major or even an effective minor in HVAC engineering in undergraduate colleges. HVAC engineering is covered in graduate and postgraduate work, and, forgive me, it ain't that hard.

Thank you for your continued work in the dissemination of information in your great publication.
Gregory I. Surfas, PE
Northside Independent School District
San Antonio, Texas

Hospital-Acquired Infections

I read the article “Air-Treatment Systems for Controlling Hospital-Acquired Infections” (January 2007) and was amazed. Wladyslaw J. Kowalski, PE, PhD, certainly is a leader in this area of our industry, and his ability to write a remarkable piece like that is equally impressive. I found the article easy to follow, even though the issue is complex.

I would like to know if Dr. Kowalski feels that UVGI (ultraviolet germicidal irradiation) provides the same benefits in residential applications that it does in medical ones and if he has any advice. Our company has, in a few cases, installed UVGI, but not to any large degree because of our lack of true understanding and proof that these devices actually do improve air quality.

I have read articles on UVGI in the past, but not found any written by someone with Dr. Kowalski's level of knowledge. Research in the residential sector is scarce, so, if Dr. Kowalski has a few moments, we would value his input.
D. Brian Baker
Custom Vac Ltd.
Winnipeg, Manitoba, Canada

Author's response:

Although the microbial problems in residential environments differ from those in health-care facilities, the solutions often are the same or, at least, very similar. Improved filtration can go a long way toward improving a residential environment; however, I have seen UVGI result in dramatic improvements in home air quality as well. Needless to say, it helps to have a central air system before you begin applying high-efficiency filtration and UVGI air treatment. Stand-alone air cleaners are another option for homeowners, but the performance of these units is unregulated, and sizing guidelines often are nonexistent. The International Ultraviolet Association and the Air-Conditioning and Refrigeration Institute are planning to rectify this problem by issuing guidelines, including some for residential applications.

It is important to consider the nature of a residential air-quality problem. The presence of airborne allergens, mold, and dust mites often can be alleviated with filtration alone; a MERV 10 to MERV 15 filter should provide considerable improvement. In homes with children, the problem often is viruses brought home from school. In these cases, UVGI may help, although there may be no absolute protection — short of quarantine — against intrafamily transmission. At present, there simply is not enough data to support every manufacturer's claims, but this does not necessarily mean the claims are invalid.
Wladyslaw J. Kowalski, PE, PhD
Immune Building Systems Inc.
New York, N.Y.

Global Warming

Dave Thomas' letter about global warming (Letters, January 2007) is filled with the kind of misleading facts I have come to expect from far-left environmentalists. As an engineer, Mr. Thomas should know better than to compare data from two such short periods of time as 1992-93 and 2004-05 to conclude that global warming is advancing at a rate of anywhere from 6 to 60 percent over an eight-year period. Why did Mr. Thomas choose those years to compare? Was it because the summers of 1992 and 1993 were unusually cool and the summers of 2004 and 2005 were unusually warm?

I track heating and cooling degree days in the southern Ohio area for my employer. By selectively choosing and comparing any two-year period, I can either validate or contradict Mr. Thomas' stated opinion. If I chose to compare the 1999-2000 cooling degree days with the 2001-02 cooling degree days in the Cincinnati area, I could make the statement that global warming for the Cincinnati area is advancing at the rate of 44.9 percent every two years. If, on the other hand, I chose to compare the 2001-02 cooling degree days with the 2003-04 cooling degree days, I would come to the conclusion that global cooling is advancing at the rate of 32.2 percent every two years.

Per the Vostok ice-core findings, there have been five global-warming periods and four ice ages over the last 400,000 years. We just happen to be at the peak of a global-warming cycle, which, by the way, is not as high as two of the previous four peaks have been.

My guess is that it will be another 100,000 years before we have the data to confirm whether we humans are or are not affecting the global-warming/ice-age cycles. Then again, 2 million to 3 million years ago, the global-warming/ice-age cycles were only a mere 40,000 years apart.

As for the suppression of scientific findings and disinformation, Mr. Thomas and far-left environmentalists seem to be doing a pretty good job of that.
Robert Strobl
West Union, Ohio

Refrigerant Data

I greatly enjoyed the fine article “Refrigerant Data Update” in the January 2007 issue. My only wish is that a discussion and/or charts of the oil change or compatibility of changing refrigerants, especially in hermetic or semi-hermetic machines, would have been included. I hope we will see this discussed in the future.
Frank McCain
Franklin Engineering
Houston, Texas

Letters on HPAC Engineering editorial content and issues affecting the HVACR industry are welcome. Please address them to Scott Arnold, executive editor, at