Where should a duct detector be placed?

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.

Table of Contents

Where should a duct detector be placed?

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.

Are duct smoke detectors required on exhaust fans?

Duct-mounted smoke detectors, however, are not required in a return air system if the spaces served by the HVAC system are protected by ceiling-mounted smoke detectors. Duct-mounted smoke detectors are also not required downstream of exhaust fans.

Are duct detectors required at fire smoke dampers?

1. Duct smoke detectors will not be required at each fire smoke damper where the supply fan shall shut down and all the fire smoke dampers associated with the supply system automatically close upon actuation of an automatic alarm initiating device on the floor(s).

Does duct detector go on 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.

What CFM requires a duct detector?

The International Mechanical Code requires a duct smoke detector in the return for units over 2,000 cfm and requires a detector in the supply duct for systems over 15,000 cfm.

How far does a smoke detector have to be from a vent?

3 feet
NFPA 72 recommends that they should not be installed closer than 3 feet from any supply air diffuser or return vent. If they are too close to the supply, smoke may not reach the detector. Also, the air coming out of the vent contains dust and dirt, which can settle in the detector and cause nuisance alarms.

Are remote test switches required for duct detectors?

You are allowed to use a remote test switch for testing duct smoke detectors to meet the requirements of NFPA 72.

What height should smoke detectors be installed?

Make sure smoke detectors are installed high on the walls or near the center of the ceilings, and at least 10 feet away from cooking appliances. When installing on the wall, place the smoke alarm within 12 inches from the ceiling. This is because smoke rises and will make the alarms the most effective.

Do duct detectors require 120V?

You can power the duct detector from either 120V power or from the fire alarm panel. If there is a fire alarm system, then you must monitor that detector for alarm and trouble. NFPA 90A-2002 6.4. 4.2 In addition to the requirements of 6.4.

How do you test a duct detector?

Spray aerosol smoke into the duct through the ¼ 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.

Can you put smoke detector in corner?

Make sure smoke detectors are at least 18 inches from a corner. Do not place a unit on an uninsulated exterior wall or ceiling. Place smoke detectors at least 3 feet from ceiling fans.

Do duct detectors need to be monitored?

Even though duct smoke detectors are not highly visible, they must be inspected regularly to remain in compliance like the rest of your fire alarm system. Per NFPA 72, duct smoke detectors should be visually inspected twice a year.

How far from the ceiling should a smoke detector be installed?

12 inches away
Wall-mounted alarms should be installed not more than 12 inches away from the ceiling (to the top of the alarm). If you have ceilings that are pitched, install the alarm within three feet of the peak but not within the apex of the peak (four inches down from the peak).

Do smoke detectors go on wall or ceiling?

Smoke alarms should be mounted in or near bedrooms and living areas, either on the ceiling or the wall. Ceiling mounting it is typically preferred as it allows the smoke alarm to be placed more centrally in the room.