3.03-4: Kramer 1952 'Winterstat' Back Valve

HHCC Accession No. 2006.071HHCC Classification Code: 3.03-4

The market for larger, out-door, air-cooled, commercial refrigeration applications grew starting in the middle of the 20th Century. With it came the need for new technology to maintain system head pressures at an optimum level, given the wide fluctuations in ambient air temperature characteristic of operating conditions in Canada. The ‘Winterstat’, operating as a ‘back valve’, was deigned to regulate the amount of liquid refrigerant in the condenser, allowing it to back up and reduce the effective condensing capacity forcing the head pressure on the system to rise to a satisfactory operating level. Model NM12, Kramer, 1952. [Rev. 080320]

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3.03 Refrigerant Flow Controls - NEC




Kramer Trenton Co., Trenton NJ.



Serial No.:



5 x 3 x6’ h


3 lbs.




Exhibit, education, and research quality, illustrating mid 20th century approaches to the stabilisation of refrigeration condensing pressure and temperature, used in large air-cooled refrigeration applications operating under widely fluctuating ambient air temperature conditions.

Patent Date/Number:

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.

Type and Design:

Heavy bronze body, 7/* in. sweat connections

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

With the expansion of the market for commercial refrigeration, in the middle years of the 20th century, for example in food stores, processing and warehousing applications, came the need for large multi-pass air cooled condensers. Hastened by water shortages and escalating water costs, air-cooling was seen as the wave of the future, bring with it new challenges in the control of condensing temperature and pressure.

The ‘Winterstat’ introduced by Kramer would be representative of one class of response. Acting as a ‘back-up’ valve it would force liquid to back up in the condenser at a set refrigerant temperature and pressure, effectively reducing condensing capacity and as a result stabilising the refrigerant at the desired pressure. The effect would be similar to that accomplished by the water pressure regulating valve used on water cooled condensers of the period, see ID # 211 and 212

Industrial Significance:
Socio-economic Significance:
Socio-cultural Significance:

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

HHCC Storage Location:
Bibliographic References:

Kramer, ‘L’ Thermobank, Manual No. TV 320, undated, Kramer Trenton Co. Trenton N. J.


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