Have you ever received a request to include an HVAC smoke detector with Cambridge heaters? Typically, engineers or building inspectors will make this request, interpreting building codes to require an HVAC smoke detector be installed on any air handling system with a capacity greater than 2,000 cubic feet per minute (CFM).

Why Cambridge Systems Do Not Require an HVAC Smoke Detector

The requirements for needing an HVAC smoke detector are clearly addressed in Section 606 of the International Mechanical Code (IMC), This section covers the requirements for utilizing an HVAC smoke detector for air handling equipment, and states: 606.1 Controls required. Air distribution systems shall be equipped with smoke detectors listed and labeled for installation in air distribution systems 606.2 Where required. Smoke detectors shall be installed where indicated in Sections 606.2.1 through 606.2.3. Exception: Smoke detectors shall not be required where air distribution systems are incapable of spreading smoke beyond the enclosing walls, floors and ceilings of the room or space in which the smoke is generated. Cambridge units fall under this exception, as our systems use only 100% outdoor air to heat and ventilate, making them incapable of spreading smoke beyond these parameters. The IMC Commentary provides further explanation on the intent of the code: It is not the intent of Section 606 to require duct smoke detectors in systems that function only as exhaust systems or only as makeup air systems. A makeup air supply system that discharges 100-percent outdoor air into a building does not withdraw air from the building and, therefore, cannot contribute to the movement of smoke. It is more important to keep in mind the intended application of Section 606, which is to address the potential hazard caused by ducted air distribution systems that link together rooms and spaces within a building, thereby providing the means to distribute smoke to such rooms and spaces. Air-handling systems of any type that cannot transport smoke beyond the area of fire origin are exempt from the provisions of this section.

Since Cambridge heaters are only used as 100% outdoor air systems smoke detectors are not required.

Question: Have you ever been required to include a smoke detector on a Cambridge unit?