In 1869, Benjamin Sturtevant patented the first hot blast apparatus, marking the beginning of the modern air-blast apparatus as applied to heating, ventilating and drying applications. The early "Sturtevant System" was centralized with air forced by a fan across steam coils then conveyed through ducts to all parts of the building. The line would expand to include unit ventilators for schools and suspended/floor type heaters for commercial/industrial work.

It was nearly a full decade after Nesbitt Co. introduced the first unit ventilator in 1917 that Sturtevant started a product line, though they patented a unit ventilator as early as 1915. As long-time believers in the Central Air System, they viewed the initial units as too bulky and noisy to be seen as a viable alternative.

With the creation of a light-weight copper heating surface,(developed by Aerofin Corp. which Sturtevant co-founded) in the 1920s, these issues disappeared and Sturtevant jumped into the fray. Originally developed for schools, unit ventilators would be in great demand in public and private buildings.

The Speed Heater suspended type unit heaters were adaptable to almost any commercial or industrial application.
The Air Washer was an early commercial air conditioning unit that purified, cooled, dehumidified and humidified the air
Air Washer
The Unit Ventilator, originally intended for schools, became a common means for ventilating all types of public and private buildings.

The Tenter Frame was a large fabric/material dryer.

The Axiflo Fan was originally developed for hull ventilation in US Navy ships.

Axiflo Fan
The Autoforce Ventilator was a natural ventilator that used the force of wind to create suction.

Autoforce Vent
The Multivane Heater was designed for big space, severe heating jobs.

Multivane Heater
The Downblast Heater had a high discharge velocity for industrial applications.

Downblast Heater