Why Stairwell Fans Must Respond to Opening Doors
A stairwell pressure-control system supplies fresh air to establish a pressure difference toward the adjoining corridor. Opening a door changes the flow area, so the fan, pressure controls and outflow routes must respond together.
Follow the air through the process
Closed doors leave leakage gaps
With a door closed, air escapes through relatively small gaps. The supply maintains a pressure difference across the doorway.
Opening the door changes the duty
The larger opening provides a much easier air path. Pressure can fall while more outward airflow is needed at the doorway.
Closing the door requires pressure control
The large opening disappears when the door closes. Fan control and a designed relief route limit excessive pressure that could make the door difficult to open.
The corridor needs an outflow route
Pressure feedback, supply points and natural or mechanical outflow form one system. Assess their combined response under the project’s specified door conditions.
Airflow function
- Supply fresh air through the installed duct and grilles.
- Operate across the specified open-door and closed-door duties.
- Work with pressure sensing, relief and the corridor outflow arrangement.
What can change the result
- Insufficient supply when a door opens can weaken the intended pressure and outward flow.
- Excessive pressure with doors closed can increase opening force.
- An incomplete corridor outflow path can prevent the planned system response.
Start with the complete air path
Share your layout and the information you already have. Unknown values can be identified before a configuration is selected.
Match the fan to this air path
Discuss LONGWELL EC backward-curved centrifugal families as component candidates for suitable fresh-air unit development. Start with the system layout and operating duties so the component can be reviewed in context.
Where it sits
In a fresh-air supply unit serving the stairwell. Pressure sensing, relief, corridor outflow, power and controls form the surrounding system.
Why consider this configuration
An EC component can be reviewed across the open-door and closed-door operating duties. Its usable control range must suit the complete pressure-control sequence.
Check the result in your equipment
Application questions
Why does opening a door change the fan duty?
An open doorway has a much larger flow area than closed-door gaps, changing both airflow and pressure.
Can a larger fan solve every pressure-control problem?
The fan must work with the pressure controls, relief route and corridor outflow. Its size alone does not establish system performance.
Does the pictured fan constitute an approved fire-safety system?
It is a component-family reference. The assembled system requires its own design review, verification and applicable approvals.
Discuss your fresh-air unit duty
Send the stairwell and outflow layout, specified door conditions and operating points. Include controls, relief arrangements and complete-system acceptance requirements.
A layout, installation photos or your existing model is enough to start the discussion.