Are duct smoke detectors required on exhaust fans?

Are duct smoke detectors required on exhaust fans?

Smoke detectors are not required in exhaust ducts. The conflicting requirements are obvious. The IMC requires smoke detectors in the return ducts. NFPA 90A requires smoke detectors in the supply ducts.

Where should NFPA smoke detectors be placed?

Install smoke alarms inside each bedroom, outside each sleeping area and on every level of the home, including the basement. On levels without bedrooms, install alarms in the living room (or den or family room) or near the stairway to the upper level, or in both locations.

Where does NFPA 90A apply?

NFPA 90A covers construction, installation, operation, and maintenance of air conditioning and ventilating systems, including filters, ducts, and related equipment, to protect life and property from fire, smoke, and gases resulting from fire or conditions having manifestations similar to fire.

What is the largest return air opening that can be protected with a single smoke detector?

2,000 cfm
Smoke detectors shall be installed in return air systems with a design capacity greater than 2,000 cfm (0.9 m3/s), in the return air duct or plenum upstream of any filters, exhaust air connections, outdoor air connections, or decontamination equipment and appliances.

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

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.

How far should a smoke detector be from a bedroom door?

Smoke Detectors are recommended to be a minimum of 36 inches from an HVAC supply vent, ceiling fan blade tip or bathroom door with a shower or tub. g. The maximum allowable distance from a hallway smoke detector to a bedroom is twenty feet on an unobstructed ceiling.

What NFPA 255?

NFPA 255: Standard Method of Test of Surface Burning Characteristics of Building Materials.

At what CFM Do you need a duct detector?

NFPA 90A and International Mechanical Code 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.

Can a duct penetrate a fire wall?

The duct shall not terminate at a wall register in the fire-resistance-rated wall. Such walls are penetrated by ducted HVAC systems, have a required fire-resistance rating of 1 hour or less, and are in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3. 1.1 or 903.3. 1.2.

Can a smoke detector be used as a NFPA?

For example, if the fan motor were to begin smoking the duct detector would, ideally, shut down the system before the fan caught on fire. Furthermore, the NFPA specifically states that detectors installed in the air duct system shall not be used as a substitute for open-air protection.

Do you need smoke detectors in exhaust ducts?

Return system smoke detectors are not required where the entire space served by the air distribution system is protected by a system of area smoke detectors. Smoke detectors are not required in exhaust ducts. The conflicting requirements are obvious.

Do you need a NFPA for an exhaust fan?

There are also exceptions to the NFPA for smoke detectors installed in duct air systems. Exhaust fan systems do not require smoke detectors, however, again always check with local codes as these normally supersede national codes such as the NFPA.

Can a smoke detector be used with multiple fans?

This should be applicable to air handlers that include multiple fans or a single fan motor. Again, always check with the immediate Authority Having Jurisdiction (AHJ) for their requirements for smoke detection and control. The codes are constantly changing so it’s good to stay updated.