Two air movers in parallel will produce double the free flow of one, while air movers in series increase the shut-off pressure to twice that of a single device. Note that at intermediate flow points, the flow and pressure increases, and whether fans should be in series or parallel depends upon the degree of system resistance, i.e. placing two air movers in series in the low resistance system shown would produce a negligible increase in flow and pressure.
Using Multiple Fans
When applying more than one fan in a system:
- "n" fans in series will increase pressure "n" times at a given flow rate, with no additional free delivery flow. Fans in series can be useful in high resistance systems.
- "n" fans in parallel will increase flow "n" times at a given pressure level, with no additional shutoff pressure generated. Fans in parallel can be useful in low resistance systems.
