M u s e u m  C r e a t e d  L e s s o n

Coal-fired 1940s Hot Water Heater and Chronotherm Thermostat

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HVACR Heritage Centre Canada, Cedar Valley, Ontario

Compact coal-fired backup hot water heater from the 1940s
A compact coal-fired, cast iron hot water heater from the 1940s
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An early automatic temperature control room 'thermostat.'
A 1930s time-temperature-actuated electro-mechanical automated room 'thermostat' gave homeowners the flexibility to set their own temperatures to operate their central home heating systems.
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Part A: Turning on the Heat ( a warm up )
1. Match the words below with their appropriate meanings. Print the letter of the meaning
beside the matching word.

a) domestic _____ b) compact _____ c) grate _____ d) exhaust fan _____

e) thermostat _____ f) complex _____ g) innovative _____ h) digital _____

A. a very complicated or involved arrangement of parts
B. draws air from the interior and expels it outside
C. pertaining to the home or family
D. involving or using numerical digits
E. arranged within a relatively small space
F. a device to establish and maintain a desired temperature
G. introducing something new
H. a frame of metal bars for holding fuel when burning
Part B1 -- Heat on full blast: Coal-fired Hot Water
1. What was the Windsor 40 model hot water heater made from? How much did it weigh?
2. What are the main components of the hot water heater ? How does each component work ?
Part B 2 -- Heat on full blast: Chronotherm Thermostat
1. Why could the Chronotherm thermostat be referred to as one of the first “green
machines” ?
2. What made this thermostat so special for its time in the late 1930’s ?
3. Describe how a person would set the thermostat for desired temperatures. Use the
terms - timing mechanism, thermometer and thumb wheel.
Further Research (Part 1)
Note: Use websites containing keywords from the questions.
1. In 1883, Warren Johnson developed one of the first “room thermostats,” which he called an electric “tele-thermoscope.” His invention sparked the creation of an industry and a company known as Johnson Controls. Describe how his early thermostat compares with the Cronotherm thermostat. Investigate how the company grew from its 1883 beginnings to its present day success.
2. What changes in families and society followed from the invention of the Cronotherm automatic temperature control and other devices like it?

Further Research (Part 2)
Note: Use websites containing keywords from the questions.
3. Investigate the thermostat in your present home. How does it differ from the Cronotherm? Investigate the background of the company that makes the your home's thermostat.
4. Predict how you think home heating may change in the future, say one hundred years from now. Consider environmental issues, resources, cost, fuel, heat sources, temperature control, etc. Be creative! Perhaps YOU will be the next great inventor to change how we heat our homes.
Answers to Part A
a) C b) E c) H d) B e) F f ) A g) G h) D
Answers to Part B1
1. - cast iron , 110 pounds
2. - firebox, grate, collection chamber, access door - turning a handle on the front of the unit tipped the grate so the ash fell into the collection chamber below where it could be removed through the access door
- water inlet connection , water outlet connection, exhaust fan -- water enters through water inlet connection, is heated by the coal, and exits through the water outlet connection, an exhaust fan carries away the heat
Answers to Part B2
1. - fuel saving, used electricity, saved energy automatically by turning heat down at night and up in the morning
2. - introduced complex, high tech , mechanical/electrical controls into the Canadian ome
3. - timing mechanism used for setting when heater should turn on or off
- disc with AM with numbers 1-12 on one half and PM with numbers 1-12 on other half
- 2 metal arms stick out for setting desired on / off times
- thermometer indicates the present temperature
- thumb wheel below thermometer used to adjust the current temperature

Learning Objectives

Part A: Turning on the Heat ( a warm up )
* Students will become familiar with vocabulary related to these topics.
Part B1: Turning up the Heat ( full blast ): Coal-fired 1940s Hot Water Heater
* Students will discover the main components of an early hot water heater.
* Students will understand how an early hot water heater operates.
Part B2: Turning up the Heat ( full blast ): Chronotherm Thermostat
* Students will understand the workings of an early model thermostat.
* Students will appreciate the innovations made in heating homes in the 1930’s.