In a sprinklered elevator hoistway and machine room, heat detectors must have which temperature rating and RTI?

• A. Higher temperature rating and higher RTI
• B. Lower temperature rating and higher RTI
• C. Lower temperature rating and lower RTI
• D. Higher temperature rating and lower RTI

Answer: (C)

In sprinklered elevator hoistways and machine rooms, you want heat detectors that respond quickly to a real fire despite the cooling and air movement caused by sprinkler activity. A lower fixed temperature rating means the detector will actuate at a lower temperature, giving earlier warning as soon as heat begins to rise. A lower RTI indicates a faster response to a given rate of temperature increase, helping the detector react promptly even when cooling from sprinkler water slows heat buildup.

So the best combination is a lower temperature rating with a lower RTI, because both aspects push the system toward quicker detection in a challenging environment. Higher temperature ratings would delay activation, and higher RTI would slow the response, reducing the chance of early warning in this critical space.