Letters – 2004-06-01

Getting Youth Interested

In the May Editor’s Viewpoint “Ah, Ute!” you state, “Frankly, most kids don’t have a clue about engineering and are more than a little scared of the profession.” Amen! And here’s why:

1. Our educational system has become enamored with moral relativism, “self-esteem,” dumbing down core courses and standards of learning.

2. Engineering is one of those areas where you can’t BS your way through, and there are absolute standards, both ethical and physical.

3. There is very little “instant gratification” in the practice of engineering. It takes mental discipline and the ability to consider and address a lot of parameters.

4. Appreciating and mastering math and science aren’t cool. Peer pressure works against trying to get people—especially young women and minorities—interested.

5. There is no real glamour in engineering. The preoccupation with pop culture and celebrity provides a further significant disincentive to the practice of engineering.

6. Engineers are valued the same way that trash haulers are; nobody notices or appreciates them until they are gone.

7. Studying for and practicing engineering is too much like work. By and large, our students are not prepared for it because we have a culture and parents who are pretty much consumed with pursuing their own pleasure.

JOHN S. FUOTO, P.E., CHANTILLY, VA.

Having gone through with three kids what you are experiencing with your son, I understand well how the 180-degree turn works. Keep up the good (and patient) work. Sounds like [your son is] a great prospect for our industry. And thanks for the good advice about exposing young people to how we improve life. At the AHR Expo 2005 in Orlando we will host the Skills USA championships to choose an HVAC/R technician to represent the United States in international competition next summer.

ED DOOLEY, ARI, ARLINGTON, VA.

Plane Wrong

In “Spirits of the Sky” (CSE 05/04, p. 36) you state that the SR-71 Blackbird “has never been viewed by the public.” This is not true, as the Pima Air and Space Museum, Tucson, Ariz., has had one on display for many years. See www.pimaair.org .

NATE RIGGLE, DESIGN FOR LIVING, LLC, TUCSON, ARIZ.

Airing HVAC Grievance

In “Wide Open Spaces” (CSE 06/04, p. 32) Senior Editor Scott Siddens does a disservice by publicizing poor and outmoded design concepts as though they were examples of good practices to be widely emulated.

Over-cool and reheat systems might have been acceptable in the ’50s and ’60s, when kilowatts were two cents apiece and before stringent requirements for indoor air quality. The best of modern design today would combine desiccant dehumidification and vapor compression technology with dry cooling coils, totally eliminating any need for reheat and saving as much as 50% on installed tonnage. After eliminating the cost for the unnecessary tonnage, the combined systems are actually even lower in first cost, as well.

Two additional benefits of this approach are that the space can be kept at or below 50% relative humidity, which will keep mold and mildew dormant. It also provides separate control of temperature and humidity for bonus green building points under the LEED program.

It is time for engineers to put away all saturated air system designs. It is no longer good enough to heat and cool. Modern HVAC designs for proper IAQ also require engineers to put more fresh air in buildings, use less energy and keep mold and mildew spores dormant. These demands can only be met by combining desiccant technology with vapor compression technology.

MEL MEYERS, PRESIDENT, BRY-AIR, SUNBURY, OHIO

Pump Ghosts

Your article “Busting Ghosts” (CSE 04/04, p.47) by Joseph R. Askew, contains some valuable information, but it also contains some serious errors. First, it misstates pump efficiency as being a pump’s overall efficiency. Wire-to-water efficiency, which takes into account pump and motor efficiency, is the overall efficiency of a pump.

Second, Figure 1, showing a generic pump curve, is without the system curve plotted on it. Figure 2 is supposed to be the same curve, but with a system curve plotted. The colors must have gotten mixed up, as there is no way the Figure 1 curve shows 6,000 gpm at 240 ft. of head based on the color schemes shown. Otherwise, the article is accurate.

TERRY ROUSE, GENERAL MANAGER, USFILTER / DAVIS EMU PRODUCTS, THOMASVILLE, GA.

Joseph Askew Responds: Mr. Rouse is to be commended for reading the article so carefully and offering excellent observations. The pump efficiency referred to was to provide a simple written background to assist with the development of a generic pump curve. The efficiency discussed is the pump’s efficiency as shown on typical centrifugal pump curves. Pump efficiency is calculated from several energy requirements, including items such as the water horsepower, hydraulic losses, disk-drag horsepower, leakage (internal) losses, as well as mechanical losses. These items make up what was referred to as the pump’s overall calculated efficiency. I did not mean to infer that this is the pumping “system” efficiency or the wire-to-water efficiency, which takes into account the motor efficiency, as well, for an overall pumping system efficiency. Many industries do consider this the only true efficiency, because it is the actual total energy required to provide the liquid from the pump. However, in the context of the article, the pump efficiency was just that—the pump’s efficiency as normally shown on a typical pump curve.

As for the figures showing generic pump curves, Mr. Rouse has a sharp eye for detail. He is absolutely correct. Whether the color scheme on Figure 1 got reversed, or the individual line descriptions as printed were reversed, there is definitely an error. The top line is the Horsepower line and not the Total Discharge Head (ft.) line as listed. The second line on Figure 1 is the pump curve Total Discharge Head (ft.) line and not the Horsepower line. Figure 2 is actually correct, showing the system curve intersecting the pump curve Total Discharge Head (ft.) line at the 6000 GPM @ 240 FT. head point and marked by the white triangle.

Due to space constraints, the really fun part of the article did not appear in print but can be found at www.csemag.com . (Click on the blue Plumbing button for “Pump Ghost Stories.”) I am sure that each of you has a pump ghost story to tell.

Do you have experience and expertise with the topics mentioned in this content? You should consider contributing to our WTWH Media editorial team and getting the recognition you and your company deserve. Click here to start this process.