Yes, you can run a pusher and a puller fan in the same ventilation circuit, but it must be done with careful design and selection. In ventilation language, a pusher fan is installed to blow air into a duct or airway, while a puller fan is installed to suck air out. When both are used together in series on one airflow path, they act like two fans in series, adding their pressure capabilities. If they are poorly matched or placed incorrectly, however, the result can be turbulence, recirculation and lower overall performance.
In mining and tunnel ventilation, a common example is a surface main fan combined with an underground auxiliary or booster fan. The main fan may push air down an intake, while a booster or auxiliary fan further along the airway pulls and pushes the same airflow, increasing pressure to overcome additional resistance. When both fans are correctly sized and their performance curves align, the system can deliver more air than either fan alone, with stable and predictable behavior.
Problems arise when the pusher and puller fans are not well matched. If one fan has much higher pressure capacity than the other, it can force the weaker fan to operate far from its best efficiency point, increasing noise, vibration and power consumption. In extreme cases, one fan can drive flow backwards through the other during transients or off-design conditions. Poor duct transitions between the two fans can also create significant losses and turbulence, reducing the theoretical benefit of running them in series.
Another risk is recirculation or short-circuiting. If there is a path that allows air to flow from the discharge of the puller fan back to the suction of the pusher fan, a recirculation loop can form. This wastes fan power and can concentrate dust or gases in a limited area. Proper placement of stoppings, doors and regulators, along with good duct sealing, is essential to prevent such loops in mining applications.
For smaller industrial or workshop systems, a push pull arrangement is sometimes used with one fan blowing into a space and another extracting air. This can help control air patterns, but again the fans should be selected so that their flow rates are compatible and that the space does not become over or under pressurised beyond acceptable limits.
In summary, you can run a pusher and puller fan together, and this is essentially running fans in series to boost pressure. To be effective and safe, the fans must be properly matched, installed with smooth duct transitions, protected against recirculation and considered within a full ventilation design rather than added at random.
