Parallel fans in same ducting system

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SUMMARY

The discussion centers on the operation of two parallel mechanical ventilation (MV) fans, each rated at 7000 cmh, within the same ducting system. When both fans are activated simultaneously, the total airflow does not simply double to 14000 cmh due to the pressure dynamics of the ducting. Instead, the airflow increase may be approximately 1.4 times the capacity of a single fan, influenced by the fans' characteristic curves and the pressure changes in the system. Understanding the flow versus pressure relationship is crucial for accurate airflow predictions.

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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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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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...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.
 
Welcome!
What "mv" stands for?
How do you keep the airflow produced by the duty fan from going through the standby fan?
 
MV = Mechanical Ventilation.
 
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