Duct Limit Control Building Code Requirement
Senasys TC duct limit control, or also known as firestat, is required among many states to be installed in large apartment complexes and commercial buildings through a building code. The firestat is a sensing device that shuts down airflow in the event of a critical temperature increase within an air duct. Senasys offers two different firestat options, fixed or adjustable; and multiple sensing element lengths are available (5″. 7.5″, 11″ or custom).
For more information about the building code regulation and how the firestat functions, continue reading below.
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“A building code, or building control, is a set of rules that specify the minimum standards for constructed objects such as buildings and non-building structures. The main purpose of building codes are to protect public health, safety and general welfare as they relate to the construction and occupancy of buildings and structures. The building code becomes law of a particular jurisdiction when formally enacted by the appropriate governmental or private authority.” – Wikipedia
Duct High Limit Control Used in HVAC Systems
Many local and regional building codes require the use of a sensing device to shut-down the airflow in the event of a critical temperature increase in the air ducts. This code was applied to mainly multi-family dwellings that shared a common HVAC system. The theory was to contain the smoke and prevent it from spreading to multiple units.
There are multiple ways of accomplishing this at a wide range of prices. One of the simplest and most cost effective is the High Limit Duct Control. The device senses a preset temperature limit and opens a set of contacts shutting down any device wired into that circuit. Once tripped the device requires human intervention to apply a manual reset to close the circuit. Some of the more common circuits that are wired through a duct high limit sensor would be the fan blower motor or the main HVAC system. See diagram below.
Senasys Duct Limit Control Details
TC Duct High Limits can be made with a fixed or field adjustable temperatures. The sensing probe length varies depending on the width of the duct: 5″, 7.5″, or 11″. The firestat mounts easily to the outside of any duct with a few screws and a hole for the probe. Once the bimetal probe (element) senses the temperature change it activates a switch that then can shut off a blower or fan. The switch can also be used to activate a set of louvers to close off air flow or turn on an alarm if needed. The TC series of duct high limit switches uses a manual reset so someone has to acknowledge the event to proceed.
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