12.10-7: Mercoid 1927 Room Temperature Control Device

HHCC Accession No. 2006.095HHCC Classification Code: 12.10-7

An early, automatic room temperature control device, in large, decorated brass enclosure, using an hydraulic bellows, temperature sensor, with large mercury bulb, line voltage switching, and calibrated scale 60 to 80 degrees F. Temperature control devices of this genre, would introduce automation into the Canadian house hold and become markers of profound social and cultural change; Type 0104111, Mercoid Corp., Circa 1927 [See also ID # 213]


12.10 Pressure Atomizing Oil Burner Equipment and Systems - Room Temperature Thermostats




Mercoid Corp., Chicago, Federal Warranted


Type 010426

Serial No.:



4 x 5 x 7’h


1.5 lbs.




Exhibit, education, and research quality, illustrating the engineering design and promotion of automatic oil heating, thermostatic controls in the first quarter of the 20th century

Patent Date/Number:

Patent pending


From York County (York Region) Ontario, once a rich agricultural hinterlands, attracting early settlement in the last years of the 18th century. Located on the north slopes of the Oak Ridges Moraine, within 20 miles of Toronto, the County would also attract early ex-urban development, to be come a wealthy market place for the emerging household and consumer technologies of the early and mid 20th century.

This artifact was discovered in the 1950’s in the used stock of T. H. Oliver, Refrigeration and Electric Sales and Service, Aurora, Ontario, an early worker in the field of agricultural, industrial and consumer technology.

This thermostat was used in a household in York County [York Region] north of Toronto in the 1920’s and 30’s.

Type and Design:

Hydraulic bellows actuated line voltage, mercury bulb switching


Decorated brass base plate and cover

Special Features:

built in line voltage connection junction box original box connector for shielded cable, used in the period original 3 inch toggle bolt used for mounting on lath and plaster walls of the period

  • 10 amp 110 volts
Performance Characteristics:
Control and Regulation:
Targeted Market Segment:
Consumer Acceptance:
Market Price:
Technological Significance:

The competing, thermostat, technologies of the day were helical bimetal spring temperature and hydraulic bellows designs. The copper bellows with heavy spring ballast appears to be less responsive for household home applications, possibly better suited to commercial situations in which Mercoid had made its name. Equipped with a finely calibrated scale, locking adjustment lever, and leveling adjustment screws, it uses a large, commercial type, 3” mercury tube switch. Much larger and much less finely sculptured than its Time-O-Stat counterpart, and without the sales appeal, it appears to be targeted on a different market segment. Requiring a robust contact structure, capable of handling line voltage motor starting current, would make this device much less responsive to room temperature changes than later, low inertia devices with heat anticipation features, see for example #ID 217 and 220

Industrial Significance:

Mercoid’s concept of what a room thermostat should look like, in order to please the tastes of the well-to-do marketplace appears well behind those of their competitor, Time-O-Stat [See ID # 215]. Considerably less elegant in appearance, this thermostat mirrors Mercoid’s experience in commercial and industrial controls of the period. It could well be the company’s initial foray into the residential, room thermostat market, where it would find that appearance was everything.

Socio-economic Significance:
Socio-cultural Significance:

In spite of the fact that the marketing of automatic oil heating had become part of the main stream of the new consumerism in North America, now the subject of national advertising [See ID # 213], it was still the first quarter of the 20th century and technology in the home was as yet not a common experience. There was, in fact, still much public concern about the presence of electricity in the home, and electrical appliances of any type, especially heating ones which would operate automatically, coming on and off without the touch of human hands. They were a source of suspicion, often fear and mistrust, while at the same time being objects of intrigue, especially for the well off who could afford to be intrigued. But it was a period, too, were there was a new desire for the comforts of home all that could be afforded in a period of wide spread economic depression.
Manufacturers of the new technologies for the home would take full advantage of the public mood, as a consequence 20th century marketing was born and along with it the use of often shameless hyperbola on a level not here-to-for found in the market place [see Williams-Oil-0-Matic advertisement in April 1926 national Geographic]. For many Canadians the words ‘oil heat’ and ‘automatic’ highly promoted, where to become synonymous with a new lifestyle, comfort and convenience, and a new popular wisdom of what 20th century life was all about, Such words would herald the promise of a new future for those that could afford it. Such terms would be part of an advance guard that would quickly follow, with the advance of ever more intrusive mechanical, electric, electronic and digital technologies. These technologies would serve to reshape every aspect of human and community life. They would be the building blocks, part of a new, manufactured 20th century reality, bring with it new encoded information, ideas, myths, beliefs, traditions expectations and wisdoms that would multiply and dominate North American life through into the 21st century. The study of culturally induced meanings and cultural significance inherent in the vast array of three dimensional objects, with which Canadians would increasingly surround themselves, starting in the early years of the 20th century, would become the subject of scholarly study well before the end of the century. For Canadians, the interest would be in coming to recognize and comprehend the messages encoded in Canada’s rich material culture, learning to read what has been called the new cultural ‘hieroglyphics’, understanding their meanings and significance for our times. The educational outcomes would be tied to helping peoples to make sense out of the overcrowded conceptual field of encoded information, ideas, myths, beliefs, assumptions, traditions expectations and wisdoms that crowd in on them from every hand in the culturally complex societies which now exist largely throughout the Western world .


G. Leslie Oliver, The T. H. Oliver HVACR Collection

HHCC Storage Location:
Bibliographic References:

See foot notes


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