Douglas Krantz - Technical Writer - Describing How It Works

Why Doesn't the Stair Pressurization Fan Automatically Turn On?

By Douglas Krantz | Descriptions

During a building fire, a Stairway Pressurization Fan builds up air pressure in the stairwell to push back any smoke that may be present.

 uring a building fire, a Stairway Pressurization Fan builds up air pressure in the stairwell to push back any smoke that may be present.


Greetings Douglas,

The fire alarm was activated, but the staircase fan did not activate.

What caused the stair pressurization fan to not run?

Thank You, MF



The Stair Pressurization Fan (SPF) is there to prevent smoke from entering the stairway escape route. See:

What is a Stair Pressurization Fan (SPF)?

If the SPF doesn't turn on, there are several possibilities.
  • The SPF control panel may be an extension of the fire alarm system. If the control panel is an extension of the fire alarm system, the fire alarm system's remotely located relay control module may have failed, and needs to be replaced.

  • Some SPFs have an extra On-Off-Auto switch (sometimes known as Hand-Off-Auto) which will manually turn ON the fan, manually turn OFF the fan, or have a signal from the fire alarm panel or SPF control panel automatically turn ON and OFF the fan.

    If the switch is there, it would be in addition to the switches on the SPF control panel and could be somewhere else entirely. If the added On-Off-Auto switch is in the Off position, this would be preventing the fan from automatically being turned on by the panel.

  • The SPF motor in the fan could have failed, or be overloaded. If power is getting to the fan motor, but the motor isn't turning on, the motor is bad or overloaded.

  • If the SPF isn't turning on, remember that SPFs (Stair Pressurization Fans) also have circuit breakers. The circuit breaker can be accidently turned off, or overloaded and then tripped off.

  • Some SPFs have Air Duct Smoke Detectors in their ductwork. If the Air Duct Smoke Detector is in alarm, that might prevent the SPF from turning on.

Other Reasons that the Stair Pressurization Fans Don't Turn On

  • Some SPFs are activated only when the smoke detector next to the stairway door detects smoke. Unless a smoke detector next to the stairway with the SPF detects smoke, the SPF won't turn on.

  • Some SPFs are activated only when any smoke detector detects smoke. Unless a smoke detector somewhere in the building detects smoke, the SPF won't turn on.

  • Some SPFs are activated when there is any fire alarm. Unless there is a fire alarm the SPFs won't be turned on. A fire alarm is different from a drill, and different from a walk-around test. The drill button or setting the system into test mode test may not turn on the SPF.

  • Another cause of the SPF not turning on could be that, to begin with, the Fire Alarm Control Panel wasn't programmed correctly in the first place, or the panel could have lost some of its programming.

There are many possibilities that can prevent the SPF from turning on. Check out the easy stuff first. Then check out the more difficult stuff.



Douglas Krantz

facpdoug@gmail.com
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