Where are duct smoke detectors required?

The International Mechanical Code requires a duct smoke detector in the return for units over 2000 cfm and requires a detector in the supply duct for systems over 15,000 cfm. Many designers require duct detectors in the supply and return in an attempt to meet both conflicting requirements.

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Also to know is, can duct detectors be mounted vertically?

Mounting the detector housing in a vertical orientation is acceptable provided that the air flows directly into the sampling tube holes as indicated in Figure 3.

In this way, do duct detectors go in supply or return? NFPA 90A requires duct detectors to be installed on the supply side of air handler units with airflows of more than 2,000 cubic feet per minute (cfm). The standard also requires a duct detector on the return side of any unit with air flows exceeding 15,000 cfm and which serve more than one floor of a building.

Hereof, how do duct smoke detectors work?

How Do They Work? Duct detectors sample currents in the air handling equipment to determine if smoke or fumes are present. If smoke is detected, the device will close dampers, stop fans and blowers, and trigger an audible and visible signal at the fire control panel, Kapparos explains.

How do you test a duct detector?

Spray aerosol smoke* into the duct through the ΒΌ inch hole for five seconds. Wait two minutes for the duct smoke detector to alarm. If the duct smoke detector alarms, air is flowing through the detector.

How do you wire a duct detector?

How many duct smoke detectors do I need?

NFPA 90A requires the first duct smoke detector to be installed on the supply side of air handler units of more than 2,000 cubic feet per minute (cfm) and requires one on the return side of units of more than 15,000 cfm and serving more than one story.

What is a duct sensor?

Duct Temperature Sensor – The duct static temperature sensor measures air temperature in the ductwork. The solid-state temperature sensing devices are commonly used in HVAC applications that are controlled by direct digital control or a modern building automation system.

Where do you put a duct detector?

To ensure correct operation, install the duct detector using the following guidelines: Install the duct smoke detector on a flat section of HVAC duct between six and ten duct widths from any bends or obstructions. Install supply-side detectors at a point downstream from the supply fan and after the air filter.

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