The application of HVAC controls starts with an understanding of the building and HVAC systems, and the use of the spaces to be conditioned and controlled. The type of HVAC system determines the control sequence. Several types of control products such as pneumatic, electric, analog electronic, or electronic direct digital control (DDC) can then do the basic control sequence.

Background. At one time, draft dampers ( by thermostat control of the dampers) controlled heating. The use of mechanical stokers for coal firing required another step in the use of control. When oil burners were introduced, the concept of combustion safety control became necessary. This involved the sensing and proof-of-flame in the proper time sequence of introducing draft, fuel, and ignition.

El uso de ventiladores para proporcionar ventilación y aire caliente se controlaba mediante amortiguadores, que variaban la fuente y el volumen de aire. El control típico de los ventiladores de la unidad se realizaba mediante controles neumáticos e incluía las siguientes características: aire exterior mínimo, aire de descarga, límite de baja temperatura y termostatos con ajustes nocturnos más bajos activados por el nivel de presión de suministro comprimido. El mayor uso de aire acondicionado condujo a secuencias de control más complejas en sistemas más grandes a monitoreo y control centralizados.