Pressure Atomizing Oil Burner Equipment and Systems – High Temperature Limit Controls
A mid 20th century, single function, adjustable temperature safety control for home “winter air conditioner”. Used for automatically shutting down the system to prevent over heating if, for example, the fan failed to come on allowing heat to build up in the furnace plennum beyond the safe operating point; equipped with helical bimetal heat sensor, single tilting mercury bulb line voltage switch, LA419, Minneapolis Honeywell, 1946. [1 of 2, similar to ID#239]
Features:
– Complete with original T. H. Oliver tag, marketed used LA419, H limit, operation OK
– Original label with wiring diagram and specifications
– With original swivel compression mounting device allowing the postioning of the temperature sensor in the furnace hot air plennum
Technical Significance:
– A mid 20th century, single function temperature limit safety controller exemplifying the materials and engineering know-how of the immediate pre W.W.II years.
– The Post W.W.II market for “winter air conditioning” was enormous and the industry sensed the potential, but there was still the public concern over the safety of all automatic equipment operating unattended in the home.
– The development of affordable, reliable high temperature limit automatic shut off control was a key to achieving market potential. Sales people, installers and service people would make a point of pointing out the safety features, why and how they worked. Some sales people would carry one of these safety controllers with them to clinch a sale.
Industrial Significance:
– The simplicity of the controller is surely a hallmark of the times, reflecting sophisticated engineering and manufacturing methods, as well as the availability of the engineering materials needed
– This controller may be one of the first class of products to be built in Canada by Minneapolis Honeywell, for the then rapidly growing market – see dateline in side cover “Toronto 17”
– Also made as a fan on-off controller, this series of limit safety controls by Honeywell would become the work horse of the industry throughout the major growth years of the winter air conditioner market in Canada, from the 1940’s through 60’s
– The original tag on the control tells the stories of the time, where controls were repaired and held in stock by service shops for quick replacement as needed.