Perfex Series 155 Magic Dial Thermostat
Here are photos of a circa-1944 Perfex Series 155 Magic Dial Thermostat, as well as the instruction manual.
Systems Help Center
Our comprehensive HVAC Systems Help Center covers a wide range of HVAC-related topics, including air conditioning and heat pumps, geothermal, hot-water heating, thermostats and controls, solar, steam heating, and warm air. We also have a section of informative and entertaining articles to help you sharpen your HVAC business skills. And our Heating Museum is a captivating journey through the evolution of HVAC technologies.
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Recent Articles
The American Society of Heating and Ventilating Engineers Guide (1929) - Hot Water Heating Systems and Piping
This chapter on hot water heating systems and piping was prepared by Professor F.E. Giesecke (Director of Texas Engineering Experiment Station in TX) for the The American...
Jarecki Radiators (1890)
Here are ratings for the Erie radiator from Jarecki Mfg Co Ltd. They were based in Erie, PA and their radiators appeared in issues of Domestic Engineering in the 1890s.
A History of the Radiator
Brian Roberts & Paul Yunnie compiled this document that contains beautiful vintage advertisements and illustrations of radiators from the mid to late 1800s and early 1900...
The Story of Herman Nelson, Founder of the Moline Heating System
This document contains the story of Herman W. Nelson, founder of the Herman Nelson Corporation and the Moline Heating System (a vacuum-vapor heating system).
Catalog of Bundy Radiatiors from A. A. Griffing Iron Co. (1890)
Click here to view a beautifully illustrated catalog of circa-1890 Bundy radiators from the A.A. Griffing Iron Co.
Dear Reader
Hello, old friend. I’m writing today to say thanks, and to say farewell. This will be my last column.
An Important Skill for Teaching Tradespeople
My six-year-old grandboy, Brendan, was in the vestibule of the diner when the bubblegum machine caught his attention. It was one of those spiral models that appeared in t...
Subdural’s Triumph
Subdural posed a question on The Wall at HeatingHelp.com in the Strictly Steam section, where some of the sharpest knives in the drawer post every day. The question was a...
Do Wholesalers Still Design Systems?
I know that some wholesalers still size equipment and design systems for their contractor customers, but I wondered to what degree this still goes on nowadays. So I asked...