7.02-8: Honeywell 1945 Automatic Pressure Control

HHCC Accession No. 2006.039HHCC Classification Code: 7.02-8

Automatic, hydraulic bellows actuated, low pressure control for commercial and industrial refrigeration equipment applications, with fully adjustable, user friendly range and differential settings, and tilting mercury bulb switching, in attractive, streamlined heavy, plated steel enclosure and handsome cover plate in stylish green, Minneapolis-Honeywell, Circa 1945.

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7.02 Refrigerating and Air Conditioning Pressure and Temperature Controls - Commercial




Minneapolis-Honeywell Regulator Co. Minneapolis, Min,


Type L414-1

Serial No.:

CS number 373-006


4 x 3 x 7 in h


2 lbs.




Exhibit, education, and research quality, illustrating the engineering design and construction idiom of the mid 20th century, by arguably the leading manufacturer of electric and pneumatic control devices of the period

Patent Date/Number:

Eight US patents listed 1598874 to 1827072 [1926 to 1931] Canadian Patent 255926 [1925]


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.

It 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.

Type and Design:

Hydraulic bellows actuated Tilting mercury bulb switching Widely adjustable range and differential settings

Special Features:

Attractive, simple elegant styling with plated steel, bright enclosure, long radius streamlined corners and decorated nameplate cover in green. A mercury bulb controller, with precision mechanism, it includes calibrated scales for cut-out and differential field adjustment and out-board replaceable and interchangeable bellows. Beautifully engineered, it is enclosed in 3 1/2” x 4 “x 2”deep 1/16” formed steel box with full, front, access cover, With miniature, built-in pendulum to help ensure plumb mounting needed for the precise operation of the mercury bulb at designated control point.

Performance Characteristics:
Control and Regulation:
Targeted Market Segment:
Consumer Acceptance:
Market Price:
Technological Significance:

A sophisticated state of the art automated refrigerant low-side pressure controller of the mid 20th century. Representative of the 1940’s and the new generation of commercial and industrial, refrigeration pressure and temperature controls that came with it - compact, precisely engineered by earlier standards,, They were well supported with installation instructions and service personnel, new for the period The L series, in its many variations, is well documented in company catalogues and in field instruction sheets, variously dated through the latter 1940’s and 50’s. The control was made in a number of versions for industrial, as well as commercial refrigeration applications, including farm milk coolers, refrigerated display cases, walk-in coolers and freezer cabinets.

Industrial Significance:

Models with snap action switching, replacing the mercury bulb, were available for applications where vibration and tilting were concerned.
The Minneapolis-Honeywell L control series represented well the mid-century control technology of the times, enabling the development of a vast range of new refrigeration applications by the Canadian refrigeration industry.

Socio-economic Significance:
Socio-cultural Significance:

The Canadian public, for their part, would be aware of an explosion of new refrigerated facilities, many of them in the form of self-served display cases to be seen in food stores, butcher- shops and bakeries across the country. What had been enabled by a new generation of controllers, in concert with a new generation of condensing units, innovative, evaporator engineering employing high efficiency designs in aluminum, as well as new TX valve technology [See HHCC Series 3.02. Artifacts ] was period of phenomenal growth in the Canadian refrigeration industry. It as a period that would see an irreversible change the eating and food preparation, storage, merchandizing, as well as food shopping habits of all Canadians.


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

HHCC Storage Location:
Bibliographic References:

See exhibit catalogues for CMX 02 and 04, item R20

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