Parallel fans in same ducting system

In summary, the conversation discusses a MV fan ducted system with two fans in parallel, each with a flow rate of 7000cmh. The question is whether running both fans at the same time will result in a total flow rate of 14000cmh, to which the answer is no. The flow versus pressure relationship must be considered, and depending on the fan's characteristic curve, the flow increase may only be around 1.4x. The term "MV" stands for Mechanical Ventilation, and it is important to ensure that the airflow from the duty fan does not interfere with the standby fan.
  • #1
KingMan
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Currently, I have a mv fan ducted system with two fans in parallel, one duty and standby (each with 7000cmh).
If I were to run both fans at the same time, do I get 14000cmh in total?
 
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  • #2
Welcome to PF.
KingMan said:
If I were to run both fans at the same time, do I get 14000cmh in total?
No. You must study the flow versus pressure relationship first.
The two fans will only double the flow if there is no increase in pressure when the two fans are operated together.
 
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  • #3
...if there is an increase in pressure due to having a fixed/the same ducting system the flow increase may be somewhere near 1.4x. I say "may be somewhere near" because fan performance follows a characteristic curve that is different for every fan, and may stray from the ideal.
 
  • #4
Welcome!
What "mv" stands for?
How do you keep the airflow produced by the duty fan from going through the standby fan?
 
  • #5
MV = Mechanical Ventilation.
 
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FAQ: Parallel fans in same ducting system

What is the purpose of using parallel fans in the same ducting system?

The purpose of using parallel fans in the same ducting system is to increase the overall airflow and improve ventilation in a specific area. By using multiple fans, the system can handle a larger volume of air and distribute it more evenly throughout the space.

How do parallel fans in the same ducting system work?

Parallel fans in the same ducting system work by pulling air from the same source and pushing it through the same duct. This creates a more powerful and efficient airflow compared to a single fan. The fans can be connected in parallel, meaning they have the same pressure and flow rate, or in series, where one fan has a higher pressure and the other has a lower pressure.

What are the benefits of using parallel fans in the same ducting system?

There are several benefits to using parallel fans in the same ducting system. These include increased airflow, improved ventilation, and better air distribution. Additionally, using multiple fans can provide redundancy in case one fan fails, ensuring continuous operation of the system.

What are the potential drawbacks of using parallel fans in the same ducting system?

One potential drawback of using parallel fans in the same ducting system is increased energy consumption. Since multiple fans are running, it may require more energy to power them compared to a single fan. Additionally, if the fans are not properly synchronized, it can lead to imbalances in airflow and cause inefficiencies in the system.

How do you determine the appropriate size and placement of parallel fans in the same ducting system?

The size and placement of parallel fans in the same ducting system depend on several factors, such as the size of the space, the required airflow rate, and the layout of the ducting system. It is important to consult with an HVAC professional to determine the most suitable fan size and placement for optimal performance and energy efficiency.

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