ACHRNEWS

'The Quiet Indoor Revolution'

May 3, 2000
“The air temperature issuing from the registers plays a large part in providing for the occupants’ comfort level. If the air temperature is barely above body temperature, a person seated next to the register might experience a chilly draft. Yet this is exactly what can happen when duct runs are long and the register is far away from the furnace.”

The results and impact of temperature drop are outlined in chapter 21 of The Quiet Indoor Revolution, a book by Seichi Konzo and Marylee MacDonald, published by the Small Homes Council-Building Research Council, University of Illinois.

At first glance, this book appears to be a history of the home heating and cooling industry. True, it holds fascinating information and a nostalgic look back for historians, contractors, and those who work in the hvacr industry.

But on another level, it offers solid, practical advice that is still beneficial to us today. For instance, chapter 20 on automatic controls describes the first limited use of continuous air circulation (CAC) control, which was an idea ahead of its time in the 1930s, but is getting a second look with the increasing need for mechanical ventilation in today’s tighter homes.

It also discusses zone control, another idea that has gained in popularity.

Balancing a duct system

The chapter noted above on duct temperatures offers some useful advice on balancing a duct system: “A circular damper in a circular duct does not restrict airflow uniformly.…For small residential systems, the cross damper and the split damper have been commonly used.”

Supporting figures and illustrations are clear and helpful. Chapter 21 on pipes, ducts, plenums, and fittings would also serve as a helpful review for many in the sheet metal trades.

The book notes the importance of the well-planned and well-constructed duct system: “Although manufacturers are inclined to emphasize the virtues of their furnace, the real key to a good installation is a well planned duct system.”

Special situations also are occasionally addressed, such as when furnace closets are located in a garage, the book warns of some of the implications of this kind of installation.

“Vagrant heat losses from the furnace casing, vent pipe, bonnet… could be substantial, even for a high-efficiency burner. One-inch-thick duct insulation is not adequate for the cold attic space. Two-inch duct insulation is the minimum that should be used.”

The hardcover book is nearly 400 pages and comes with a handy index, from Acclimatization to Zone heating.

Cost is $39.95 plus shipping. It is available by calling 800-336-0616 and requesting order number Sp-11. Or write the Building Research Council, University of Illinois, One E. St. Mary’s Rd., Champaign, IL 61820.