Thermotank Ltd

The business was based on Alexander’s invention, the Thermotank, a system designed for maritime use which could maintain a constant temperature coupled to a change of air on board ships.

[1] In 1922, Alexander Stewart invented and patented the Punkah Louvre a device able to control and direct the supply of air as required.

In 1897, Alexander William Stewart,[4] head of the electrical department at shipbuilders J&G Thomson & Co,[5] at Clydebank on the River Clyde, invented apparatus which he called the Thermotank.

[8] In 1898, Alexander William Stewart patented his invention in the United Kingdom under the heading ‘Improvements in ventilating and heating or cooling apparatus for use on board ship’.

Early in 1901, the Thermotank system was installed on the Japanese steamer Kumano Maru which was under construction at the Fairfield Shipbuilding and Engineering Company shipyard in Glasgow.

The system was described by The Marine Engineer and Shipping Gazette and Lloyds List as: The arrangements for ventilating and heating or cooling the cabins are novel and are the result of much careful thought.

Four of Stewart’s patent Thermotanks, with the necessary electric fans etc., have been introduced, and work in conjunction with steel trunks led to the various compartments.

Its temperature may also be controlled, for a system of brine pipes from the refrigerating machine connects with the Thermotank coils, and in warm climates the circulating air may be cooled.

Stewart’s Punkah Louvre, in addition to becoming one of the most ubiquitous objects of the 20th century, allowed air to be delivered at speeds of between 30 and 50 feet per second.

About 450 miles of trunking was manufactured as well as ventilating fans for coal mines, underground railways and refrigerated food stores.

By 1945, Thermotank equipment had been fitted in more than 50 million tons of shipping, in large numbers of trains and aircraft, and in many famous public buildings.

In 1962, Hall Thermotank acquired the Searle Manufacturing Co Ltd., makers of heat transfer products used in air conditioning and refrigeration.

Glasgow concentrated on consultancy, design, supply installation and commissioning of marine air conditioning, heating and ventilating equipment.