Duct Detectors Smoke Detection – NFPA 90A Code Requirements

What you will learn from Duct Detectors Smoke Detection - NFPA 90A Code Requirements article:

  1. Preface for the NFPA 90A requirements for duct detectors in air conditioning and heating equipment.
  2. The question: Where do you install duct detectors in duct work?
  3. detailed answer to satisfy requirements
  4. exclusions and exceptions to the requirement
  5. references for further information about HVAC equipment and fire safety
  6. Finally, additional related information about fire and smoke dampers regarding HVAC


Duct Work and High Ceilings | HVAC Duct Work Systems

Duct Work and High Ceilings

Duct Work and High Ceilings | HVAC Duct Work Systems

Duct Work and High Ceilings – I did not see any reference to my question and would appreciate a response as soon as possible, as due to medical situation, have to make a decision soon. We own an OLD house with 13′ ceilings in a large part of the home and 11″ ceilings in the LV/DR and BR. We are oscillating on where to place the ducts….Floor or ceiling. It appears to be counterproductive to me to put the duct work in the ceiling since it will have so far to go. We are looking for the most cost-effective, not upfront cost but operating cost, solution. In addition, we are considering DF heat pumps. The house will need 2 or 3 to be zoned correctly. Please let me know about the duct placement and thank you for your help? (more…)

Air Conditioner Ductwork Leaks | Leaky Duct Work

Air Conditioner Ductwork Leaks | Leaky Duct Work - A good consideration when replacing the air conditioning system is the duct work.

Air Conditioner Ductwork Leaks

Red Arrow Shows a Duct Work Leak

Duct work seems to be the most ignored part of an HVAC system. However, it is a very important consideration in this age of new technology and higher energy efficient equipment being developed and manufactured. You can have the most energy efficient engine but if its in an old 60 or 70’s model car your efficiency is going to suffer. The same is true with HVAC systems. (more…)

Magnehelic Duct Pressure Sensor

Magnehelic Duct Pressure Sensor - Magnehelic Duct Static PressureMagnehelic Duct Pressure Sensor - The magnehelic measures duct pressure inside of ductwork. It is important, for many reasons, to know the pressure inside of duct work. This magnehelic measures the supply side pressure of the blower inside the air handler. The static pressure in this system is actually controlled by a static pressure transducer which is directly hooked up to a DDC controller that controls a variable frequency drive based on static pressure. The static pressure transducer is a solid state magnehelic and works in much the same way a magnehelic works except the transducer is digital and sends out a signal that registers the pressure it is reading. The magnehelic pictured is simply for visual display and reading the static pressure inside the air handler. It does not send out any signals. (more…)

Duct Systems and Bad Ductwork

Duct Systems and Bad DuctworkBad Ductwork - Ductwork is necessary to deliver the air throughout the HVAC system. It is important that the system has integrity with no leaks. Duct work is made of different materials. Duct systems also have different construction methods which hold the ductwork together.

Pictured above is an old ductwork system (which needs to be replaced) made of duct board, which is a rigid fiberglass board, and flex duct work. The duct board is cut to size from the duct work sizing requirements for tonnage and taped together with special duct tape. For the branches coming off the duct board trunk, metal collars are inserted into holes cut to size in the duct board. Flex ductwork is attached to the metal collars for the branch ductwork. (more…)

HVAC Duct Systems

HVAC Duct Systems - Round Hard Duct WorkHVAC Duct Systems - Ductwork systems channel the air to the spaces where it is needed from the air handler. HVAC duct systems also pulls the air from the space and channels it back to the air handler where it needs to be conditioned. In some commercial applications the area above the ceiling is considered the return duct. All the return air is channeled back to the air handler through the plenum where it is conditioned in the air handler. Part of the conditioning process is the air being passed through a filter and then an exchanger like a coil or heat exchanger. (more…)

Duct Work | Heating and Cooling Mechanical

Duct WorkMost air conditioning and heating systems require some form of duct work. Duct work channels or directs the air to places in the dwelling where the conditioned air is needed. There are many types of ductwork available. Often times the ductwork can make a big difference in your utility bills. For that reason, it is important that the ductwork is installed correctly by qualified installation technicians. (more…)

Ductwork Integrity & Insulation | HVAC Airflow

Ductwork Integrity & Insulation | HVAC Airflow 

Ductwork Integrity & InsulationSo you are having a new HVAC system installed and you selected a system that is high efficiency and you want to get the most out of it. Have you looked at or has the HVAC contractor looked at the duct work and determined if it is good enough for the high efficiency system. A good HVAC contractor would look at the ductwork to make sure it is adequate and sized properly for the new system. This is often done as the HVAC contractor wants to ensure that the new system is properly matched to the HVAC ductwork lest the system not work as it should. Beyond that the most overlooked part of the ductwork is the ductwork integrity.


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