The Hartman Company Newsletter

Issue: July, 2002
Topic: The Controls Revolution Won't Wait For Us!

Dear Hartman Company Newsletter subscriber,

This is no time for complacency. Whether our job is focused on engineering, 
manufacturing, or the end use of HVAC systems, the people we serve are likely 
to soon become very unhappy as they begin to learn how much money our inability 
to adapt to new technologies is costing them. Sure, there are a lot of changes 
taking place now. It was a surprise to learn recently that one major chiller 
manufacturer who until two years ago was on record as saying that variable speed 
is not effective for centrifugal chillers is now fitting nearly 50% of their 
current production with variable speed drives.

But the changes our industry is now experiencing are only magnifying the problem. 
When this chiller manufacturer was asked how they recommended these variable speed 
chillers be controlled in their applications, a lack of understanding about the 
full implications of variable speed on overall chiller and chiller plant 
performance became embarrassingly evident. This "expertise gap" is responsible for 
wasting capital cost and energy as our industry makes the important shift from 
constant speed to variable speed for fans, pumps, and compressors.

Most in the industry still don't seem to understand that the inevitable change to 
variable speed equipment mandates new methods of control as well as the switch 
from constant to variable speed drives. Until this point is better understood and 
our industry begins offering products, designs and system operations that embrace 
the special requirements and benefits of variable speed more completely, we will 
continue to employ building comfort systems that cost much more than necessary and 
operate nearly 50% less efficiently that otherwise possible.

To offer a primer for interested engineers about the opportunities of combining 
variable speed with more effective control, we have assembled the following elements 
from our firm's resource database:

1. An ASHRAE paper by our firm's Principal presented almost a decade ago that 
explains the full benefits achievable by applying variable speed control of air 
supply fans. Among the many typical benefits is one seldom employed -- reducing 
building energy use and improving building IAQ by keeping the fans running! This 
paper is available at:

http://www.hartmanco.com/pdf/p02.pdf

2. A paper Mr. Hartman presented to an International Conference on Renewable and 
Advanced Energy Systems For the 21st Century in 1999. This paper shows how effective 
control along with variable speed pumping allow chilled and heating water 
distribution systems to perform far better than the crude "variable primary flow" 
system approaches now employed. This paper  can be found at:

http://www.hartmanco.com/pdf/pre12.pdf

3. Another technical paper that Mr. Hartman delivered to the APEC sponsored Green 
Building Workshop and Conference in 2000 titled "Network Based Control: An 
Imperative for Green Office Buildings" provides an in-depth discussion of the need 
for new control strategies when variable speed equipment is employed. This paper 
can be found at:

http://www.hartmanco.com/pdf/pre15.pdf

4. An on-line essay written by  Mr. Hartman for automatedbuildings.com outlines 
his thoughts on the timing of the current controls revolution and when the prime 
mover ensures it will be completed. This essay can be found at:

http://www.automatedbuildings.com/news/jul02/articles/htmn/htmn.htm

5. Finally, for the very latest in control developments, please watch for Mr. 
Hartman's two part Control Freaks column series in the July and August issues of 
HPAC magazine. This series will explain why PID controls are no longer effective 
in the variable speed era and what type of control concepts are needed to replace 
it.

To search the Hartman Resource Library yourself for additional articles on this topic, 
go to:

http://www.hartmanco.com/cgi-bin/dbman/db.cgi?db=resource&uid=default&view_search=1


Linda Zuvich, Editor
THC News
The Hartman Company


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                                  The Hartman Company
                       An HVAC Engineering & Technology Development Firm
                                http://www.hartmanco.com