smoke detector near HVAC return

This appears to be a bad location for a smoke detector to me. Does this violate any code? I’m writing it up as a safety hazard anyway but just want to know if there is a specific code that it violates.

Codes are local.
On the practical side may I as what you are worried about?

I am trying to understand how it is a safety hazard.

Good location. If fan is running, smoke will be drawn back to the return air

I agree. I would think that placing it near the return would draw smoke from a wider area and give the alarm a wider range of coverage. I don’t see a safety issue.

He may have misspoke and been comparing it to a kitchen area which is a bad location due to nuisance tripping.
Not to put words in Johns mouth .

Actually, I was thinking that maybe with the fan running the return would draw smoke away from the detector and not allowing it to be activated. Am I over braining this one?

I think you might be.

When air supply and/or air return ducts are present in a room
or space, the detector(s) should not be placed in the path of
the air flow supply or return (NFPA 72-2007).

Placement of detectors near air conditioning or incoming
air vents can cause excessive accumulation of dust and dirt
on the detectors. This dirt can cause detectors to malfunction
and cause unwanted alarms. Detectors should not be
located closer than 3 feet from an air supply diffuser or an
air return vent.

flo lighting can also be a problem, you’ll have to read or search on your own

A HA!! I was right! Albeit for a totally different reason. Good info Gary. I learned something today.:):slight_smile:

the Bride allows me to accept tips, even if you call me Gary :mrgreen:

[FONT=Slimbach-Book][size=1][FONT=Slimbach-Book][size=1][size=2]There is nothing wrong with that installation.

As in more commercial type smoke detection in ventilation equipment.

Supply duct smoke detector installation should be downstream
of fans, filters, chillers, heaters, and humidifiers.
Duct smoke detectors in the return air stream should be
located at every return air opening within the smoke compartment,
or where the air exits each smoke compartment,
or in the duct system before air enters the return air system
common to more than one compartment.

The principals are the same, just a less expensive detection system. :slight_smile:

Barry, Gary, tomato, tomoto. LOL.

Sorry bout that.:neutral:

Barry is most likely right due to the fact that residential systems don’t have a filtration system that the like of a commercial air system. :slight_smile:

Don’t install smoke alarms near windows, doors, or ducts where drafts might interfere with their operation.

Where not to place smoke detectors?

One of the major causes of unwanted alarms is improper placement of detectors. The best way to avoid unwanted alarms is not to install detectors in environments that can cause them to malfunction, or to install detectors specially designed for those environments. Examples follow:
• Excessively Dusty or Dirty Areas: In excessively dusty or dirty areas consider using the Filtrex™ smoke detector. This detector incorporates a microprocessor-controlled air intake fan and filter that allows the unit to be installed in areas where ordinary detectors cannot be used. Filtrex is an intelligent smoke detector that removes airborne particles before they reach the sensing chamber. It is ideal for textile mills, dusty manufacturing facilities, paper mills, and recycling centers.
• Outdoors: Avoid using detectors outdoors, in open storage sheds, or other open structures affected by dust, air currents, or excessive humidity and temperature extremes.
• Wet or Excessively Humid Areas: Avoid damp, wet or excessively humid areas, or next to bathrooms with showers.
• Elevator Lobbies: Do not place over ashtrays or where people will smoke while waiting for the elevator.
• Extreme Cold or Hot Environments: Avoid very cold or very hot environments, or unheated buildings or rooms where the temperature can fall below or exceed the operating temperature range of the detector. At temperatures above or below the operating range of the detector*, its internal components may not function properly. *Manufacturers’ specifications should list acceptable temperatures in these ranges.
• Areas with Combustion Particles: Avoid areas where particles of combustion are normally present, such as in kitchens or other areas with ovens and burners; in garages, where particles of combustion are present in vehicle exhausts. When a detector must be located in or adjacent to such an area, a heat detector may be appropriate.
• Manufacturing Areas: Avoid manufacturing areas, battery rooms, or other areas where substantial quantities of vapors, gases, or fumes may be present. Strong vapors can make detectors overly sensitive or less sensitive than normal. In very large concentrations, gases heavier than air, such as carbon dioxide, may make detectors more sensitive, while gases lighter than air, such as helium, may make them less sensitive. Aerosol particles may collect on detector chamber surfaces and cause nuisance alarms.
• Fluorescent Light Fixtures: Avoid placement near fluorescent light fixtures. Electrical noise generated by fluorescent light fixtures may cause unwanted alarms. Install detectors at least 1 foot (0.3 m) away from such light fixtures.

  • The guidelines on this page are adapted from Standards published by the National Fire Protection Association, Quincy, Massachusetts, USA. These standards include NFPA 72, National Fire Alarm Code; NFPA 70, “National Electrical Code”, Article 760; and NFPA 90A, “Installation of Air Conditioning and Ventilating Systems”.:slight_smile:

In our area smoke detectors cannot be placed within 2 feet of an air return. The reasoning is that if the smoke is coming from the return side first it will get sucked up before the detector can and thus the detector is rendered useless.


Jim, that was my original reasoning for identifying this as a possible safety issue.

\John you were correct in your original thinkinmg.:cool:


Judging from the supplied picture the grill depicted does not appear too have a filter installed or for that matter away to access a filter (ie hinges)
leading me too believe that this is a non-pressurised “jump over” return that is connected to one or more sleeping room too meet the requirement of a balanced return air system. If this is the case there is no minimum clearance requirement for smoke detectors from a non-pressurised return.

Time to see the eye Doc there Mark! :wink:

That looks like a dinky 3 bdrm (no jump over needed).
Screw latches right there in plain view.