Lawler's Patent Model of a Hot Water Heater - 1877


This model was filed with the application to the U.S. Patent Office for Patent Number 189,314 issued to Edward Lawler of Hartford, Connecticut on April 10, 1877. Mr. Lawler’s patent was for an improved water heater which would be fed from the normal water mains and which would have the ability to maintain a ready to use reservoir of hot water. He specifically noted its potential use in shops where hot drinks such as coffee were served. His design consisted of two cylindrical tanks made of cast iron. The hot water reservoir, the taller of the two tanks, was mounted on three legs elevating it over the shorter boiler and heating chamber located alongside it. Cold water from the mains entered via a pipe extending from the top of the reservoir to near the bottom. Hot water exited the reservoir through a hole and pipe at the very top. The boiler was connected to the reservoir via two pipes. The lower pipe received cold water from the bottom of the reservoir, and the upper pipe passed hot water into the reservoir where it entered well above the bottom of the pipe supplying cold water from the mains. The hot water, being of lesser density (specific gravity) than the cold, would rise to the top of the reservoir to be ready for dispensing. As hot water was drawn off for use, cold water would enter at the bottom to again fill the reservoir and pass into the boiler to be heated. Mr. Lawler’s design called for the boiler to sit atop a heating chamber of the same diameter which could be heated by gas or other fuels. Research of available trade literature and other sources has not revealed any commercial use that may have made use of Mr. Lawler’s invention.

The patent model is constructed of copper. The reservoir and boiler are modelled along with the pipes interconnecting them as described in the patent. The cold and hot water connections are present at the top of the reservoir. Also shown at the bottom of the reservoir is a pipe that could be used for draining the system for cleaning. In its present condition the model does not include the heating chamber; however, the bottom of the boiler does model the flange described in the patent whereby the boiler would be secured atop the heating chamber. Diagrams showing the complete design can be found in the patent document online (

Patent Date: 1877-04-10

Inventor: Lawler, Edward

Location: Currently not on view

Associated Place: United States: Connecticut, Hartford

Subject: Patent ModelsHeating


See more items in: Work and Industry: Mechanical and Civil Engineering, Engineering, Building, and Architecture, Patent Models


Exhibition Location:

Credit Line: Gift of Raymond F. OReilly, Valley Stream, New York

Data Source: National Museum of American History

Id Number: 1997.0380.07Catalog Number: 1997.0380.07Accession Number: 1997.0380Patent Number: 189,314

Object Name: patent model, heater, hot waterObject Type: Patent Model

Physical Description: copper (overall material)Measurements: overall: 9 in x 6 3/4 in x 3 in; 22.86 cm x 17.145 cm x 7.62 cm


Record Id: nmah_1377258

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