What is HVAC shutdown?
RE: HVAC system shutdown – fire detection system And it is this detector that will shutdown the unit, when the unit is actually sensed to be spreading smoke. This sensing of smoke also needs to be communicated to the fire alarm control panel.
What are the requirements of NFPA 72?
NFPA 72 only provides requirements for the installation, performance, testing, inspection, and maintenance of the fire alarm system. NFPA 101®, Life Safety Code® and other codes determine whether a fire alarm system is required in a given occupancy.
What type of device causes the HVAC shutdown?
Most circuit boards are equipped with several different relays, which are used to send signals to various other systems, including the fire alarm control panel to trigger the alarm and the HVAC control system to close the dampers and shut down the fans. There will also be a relay for signaling the supervisory panel.
Do exhaust fans need to shut down with fire alarm?
When any building or floor is provided with an air system utilizing recirculated air and is protected by an automatic sprinkler system or an automatic fire alarm system, provisions shall be made to automatically stop the fans serving the affected area when the sprinkler system or fire alarm system are installed in the …
Why is NFPA 72 compliance needed?
NFPA 72 provides the latest safety provisions to meet society’s changing fire detection, signaling, and emergency communications demands.
How often is NFPA 72 updated?
every 3 years
The NFPA 72 (National Fire Alarm and Signaling Code) is a standard published by the National Fire Protection Association every 3 years for installation of fire alarm systems and emergency communication systems in the United States.
How many CFM is a 5 ton unit?
2,000 cfm
A 5-ton system should have have 2,000 cfm, a 6-ton system should have 2,400 cfm, and so on and son. Measuring how much airflow measurements deviate from that math is a quick way to diagnose airflow issues in a residential duct system.
Where are duct smoke detectors required?
The International Mechanical Code requires a duct smoke detector in the return for units over 2000 cfm and requires a detector in the supply duct for systems over 15,000 cfm. Many designers require duct detectors in the supply and return in an attempt to meet both conflicting requirements.
How do you test a duct smoke detector?
Spray aerosol smoke* into the duct through the ¼ inch hole for five seconds. Wait two minutes for the duct smoke detector to alarm. If the duct smoke detector alarms, air is flowing through the detector.
Where is AC shut off switch?
Many outdoor AC units have a shut-off switch. These switches are typically located near the unit and are inside a metal box mounted to the exterior of your home. They are sometimes labeled as an emergency shut-off.
What do you need to know about NFPA 72?
Understand NFPA 72: National Fire Alarm and Signaling Code to ensure code compliance with system integration. For engineers, coordination is a term that is critical when integrating a fire alarm system with an HVAC system or building automation system (BAS). Although for contractors installing the systems, this can be difficult.
When does the fire alarm shut down the HVAC system?
When a fire is detected, rather than allowing the whole building to fill smoke, the fire alarm system closes the fire doors, closes the fire dampers in the ductwork, and shuts down the air circulating fans. This isn’t really an issue of what the rules or codes say, though, this is an issue of life safety.
Where does the NFPA say to shut down the fan?
Somewhere in the NFPA Code, the Code does say to use the air duct smoke detector that is next to the damper to shut the damper, and the Code does say to use the air duct smoke detector at the air handling unit to shut down the fan.
Do you need NFPA 72 for duct smoke detector?
If one uses a duct smoke detector, it only needs to shutdown the air handler unit it is connected to. Also, NFPA 72 only requires that the activation of the duct smoke detector to transmit a supervisory signal – it does not need to activate audible or visual alarm notification devices.