Reader Mail: 07/05/2004

I have always had the belief that our strengths also bring about our weaknesses. A strong competitiveness, will to succeed and a big ego can lead us down the path to success, but those same traits may also be responsible for actions taken that we later regret. (This reminds me of General George S. Patton.)

Anyway, forgive my ramblings. I understand and sympathize with your words and emotions. Hopefully, you and others will benefit from stating them publicly. And a special thanks for telling the story of Tom McCart. It helps me re-establish my own priorities and appreciate the accomplishments of one I've never had the privilege of knowing.

Richard V. Osgood
Mail Concepts Inc.
Jacksonville, Fla.

Tom McCart - A Winner

I just finished reading the two articles "Raw Truth About An Incredible Man" and "A Testament To A Million Dollar Salesman," May 31 in The News and I wanted to touch base with you. I started reading the first article and started to get choked up. I wanted to stop and come back at a different time, but couldn't leave it.

Hopefully, these articles will enlighten folks that aren't familiar with what he has done for our industry. As I was rereading your article, I think that the word "incredible" is as good of a word to describe him until Webster comes up with another word that is better.

I am making some copies of the article to give to our people at work. They need to know of the fight in a person that has done so much for the industry that is providing them their living.

I am also going to take copies to my church this Sunday and share it with the people in my department and class. Tom is on the prayer list and I want them to see the person they have been praying for and see a little more about the guy that I have told them about. Tom said that he wanted to be a winner. I don't think that there is any sane person that would think that he did not accomplish that goal many years ago. He has built a legacy that will be remembered for years to come.

Tom Atchley
Fort Smith, Ark.

[Editor's note: Tom McCart passed away on June 10. The preceding letters were received prior to his death. Mr. McCart's obituary appeared in the June 21 issue.]

Utilizing Drives To Meet ASHRAE Standard 90.1

Since motors consume a majority of the electrical energy produced, the control of motors, based on demands of loads, increases in importance as energy supplies become ever more strained. Additionally, end users of motors can realize 25 percent to 70 percent energy savings via replacement of constant-speed starters. (Despite these benefits, the majority of motors continue to be operated without drives.)

Because drives are critical in optimizing the use of energy in HVAC systems and on individual motors, it is useful for engineers to pay attention to the current requirements for using them to meet government-mandated energy-efficiency measures.

Consider the following. ASHRAE 90.1 is an opportunity for engineers and contractors to help customers meet this standard, which many states have adopted.

In 1999, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published an updated ASHRAE/IESNA 90.1 standard mandating energy-efficiency measures for HVAC motor systems. Designed to minimize energy consumption without sacrificing the comfort or productivity of building occupants, the ASHRAE code states that individual variable air volume fans with motors 30-hp and larger need to: (1) be run by an electrical or mechanical variable-speed drive; (2) be a vane-axial fan with variable pitch blades; or (3) have other controls and devices that result in fan motor demand of no more than 30 percent of design wattage at 50 percent of design air volume, when static pressure setpoints equal one-third of the total design static pressure, based on manufacturers' certified fan data.

ASHRAE standard 90.1 also mandates energy-efficient requirements for pumps in HVAC systems that have a total system power exceeding 10 hp. According to section 6.3.4, "HVAC pumping systems that include control valves, designed to modulate or step open and close as a function of load, need to be designed for variable fluid flow and capable of reducing pump flow rates to 50 percent or less of the design flow rate.

"Individual pumps serving variable-flow systems with a pump head exceeding 100 feet and a motor exceeding 50 hp need to have controls and/or devices (such as variable-speed control) resulting in pump-motor demand of no more than 30 percent of design voltage at 50 percent of design water flow. The controls or devices have to be controlled as a function of desired flow or maintain a minimum required differential pressure, which is measured at or near the most remote heat exchanger or the heat exchanger requiring the greatest differential pressure."

The Energy Policy Act of 1992 requires state and local governments to meet these standards to be more stringent. Today, many states have adopted the 90.1 code.

Drives are highly flexible and can be customized to meet the precise needs of single-motor HVAC applications such as fans, pumps, dampers, compressors and cooling towers.

These units convert AC power to DC, and then invert the DC back to an adjustable AC output to a motor. These drives cover a full range of powers and voltages. Single drives also feature a wide range of built-in features as standard equipment. They can be installed for most HVAC applications right out of the box; and they also can be ordered and manufactured as a customized unit for a particular application. As standards continue to be adopted, expect drives to play an increasingly critical role in helping customers meet and exceed energy efficiency regulations.

Thomas Lowery
HVAC Eastern Regional Sales Manager
ABB Inc., Low-Voltage Drives
New Berlin, Wis.

Send letters to Reader Mail, The News, P.O. Box 2600,Troy, MI 48007; fax to 248-362-0317; or e-mail to markskaer@achrnews.com.

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Publication date: 07/05/2004