The primary purpose of the duct detector on the supply side is to shut down the air handler if fire is detected in the fan or filter. This would protect the equipment and keep smoke from being distributed to the air conditioned space.Considering this, do duct detectors go on supply or return?
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.
Also Know, how do you reset a duct detector? If the difference is greater than 0.15 volts, there is enough air flow through the duct smoke detector for proper operation. Test/Reset Button - Press and hold the test button located on the power board cover for at least 2 seconds.
In this way, where do you put a duct smoke detector?
NFPA 90A requires duct smoke detectors to be located in the supply duct downstream of air filters and ahead of any branch connections.
How do you clean a duct detector?
In addition to vacuuming the inside of your smoke detector, you should also use a clean wipe and mild detergent to remove build-up from the outside of your unit. In particular, you will want to clean the vent openings, to ensure that airflow is not obstructed to the sensor inside the unit.
How much area does a smoke detector cover?
In compliance with the National Fire Protection Association (NFPA), smoke alarms will cover a radius of 21 feet, and an area of coverage of 1,385 square feet. The maximum distance between two smoke alarms should be 30 feet. If a hallway is greater than 30 feet, a smoke alarm must be installed at each end.How close can a smoke detector be to a return air grille?
NFPA 72 recommends installing smoke detectors a minimum of 3 feet from any air supply or return air grill. They may need to be installed farther away when air velocity is higher than normal.How does a duct smoke detector 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 smoke detector with a magnet?
Magnet Test vs Smoke TestThe magnet only closes a magnetic reed switch in the electronics. This switch mimics the signal that indicates that the smoke chamber detects smoke. However, the magnet does not test whether or not the smoke chamber can detect any smoke. The smoke detector looks for particles in the air. 
William Taylor 
