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The definition of a closed loop control system according to the British Standards Institution is "a control system possessing monitoring feedback, the deviation signal formed as a result of this feedback being used to control the action of a final control element in such a way as to tend to reduce the deviation to zero."
A thermostat exerts control by switching heating or cooling devices on or off, or by regulating the flow of a heat transfer fluid as needed, to maintain the correct temperature. A thermostat can often be the main control unit for a heating or cooling system, in applications ranging from ambient air control to automotive coolant control.
Building automation (BAS), also known as building management system (BMS) or building energy management system (BEMS), is the automatic centralized control of a building's HVAC (heating, ventilation and air conditioning), electrical, lighting, shading, access control, security systems, and other interrelated systems.
Air coil freeze stat. A freeze stat is a temperature sensing device for HVAC that monitors a heat exchanger to prevent its coils from freezing.Freeze stats can be used on both refrigerant-to-air, and refrigerant-to-liquid type heat exchangers and serve different purposes with similar goals for each.
There are many types of physical devices that can act as inertia dampers: Stockbridge damper - absorbs resonant wave motions in wire and support cables, seen on high voltage power lines. [2] Shock absorber - motion redirected as heating of viscous oil forced through a restrictive passage [3]
An indirect contact or direct contact condensing economizer will recover the residual heat from the combustion products. A series of dampers, an efficient control system, as well as a ventilator, allow all or part of the combustion products to pass through the economizer, depending on the demand for make-up water and/or process water.
An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning system. [1] An air handler is usually a large metal box containing a blower, furnace or A/C elements, filter racks or chambers, sound attenuators, and dampers. [2]
(The latter are more properly described as packaged terminal heat pumps or PTHP). PTACs with support for external heating through a hydronic heating coil or natural gas heating also exist. Typical PTAC heating and cooling capacity values range from 7,000–19,000 BTU/h (2 to 5.5 kilowatts) nominal. [3]