What is the minimum distance for mounting a spot-type smoke detector from an air supply diffuser?

What is the minimum distance for mounting a spot-type smoke detector from an air supply diffuser?

• A. 3 feet from diffusers
• B. 1 foot from diffusers
• C. 6 feet from diffusers
• D. 2 feet from diffusers

Answer: (A)

Detectors rely on sampling the room air for smoke, so you want to place them where the air is well mixed and not dominated by a strong draft. Keeping a spot-type smoke detector at least 3 feet away from an air supply diffuser reduces the impact of the supply air’s velocity on the sensing chamber. If the detector sits too close to the diffuser, the moving air can carry smoke past the sensor or cause dust and drafts to trigger false alarms or delay detection. The 3-foot distance is a standard guideline that helps ensure reliable smoke detection while avoiding interference from HVAC air currents. While some installations may allow other distances per manufacturer instructions, 3 feet is the commonly cited minimum.

Detectors rely on sampling the room air for smoke, so you want to place them where the air is well mixed and not dominated by a strong draft. Keeping a spot-type smoke detector at least 3 feet away from an air supply diffuser reduces the impact of the supply air’s velocity on the sensing chamber. If the detector sits too close to the diffuser, the moving air can carry smoke past the sensor or cause dust and drafts to trigger false alarms or delay detection. The 3-foot distance is a standard guideline that helps ensure reliable smoke detection while avoiding interference from HVAC air currents. While some installations may allow other distances per manufacturer instructions, 3 feet is the commonly cited minimum.