When to replace a centrifugal fan
A damaged casing, deteriorated impeller, persistent faults or changed laboratory work can prompt a replacement review. First establish what failed and whether the connected system still suits its task. A new fan cannot correct an undersized duct, inadequate make-up air or an unsuitable discharge location on its own.
If the existing fan is repairable, compare the repair scope, availability of compatible components and the condition of the whole assembly. Our centrifugal fan explanation shows the components involved. For a wider equipment decision, read fume cupboard repair or replacement.
The measurements a replacement selection needs
Gather the required airflow and pressure at the proposed operating point, including the pressure basis and air conditions. An old model number is useful, but the original selection may no longer describe today's duct system or process. Keep a copy of the existing fan curve and commissioning results where available.
- Fan model, serial number, rotation and speed.
- Inlet and outlet dimensions, orientation and available space.
- Airflow, pressure and the measurement locations.
- Chemicals, concentration, temperature and possible condensate.
- Motor supply, rating, control arrangement and protective functions.
- Mounting, access, lifting route and connected duct supports.
Include photographs of accessible labels and the surrounding installation. Have a competent person obtain measurements requiring access to operating equipment.
Replacement exhaust fan selection
The fan's wetted materials must suit the actual chemical stream. Consider normal use, cleaning and foreseeable carryover. Check the chemical suitability of the motor's position, seals, casing, impeller and connected ductwork as a complete system.
Our Fumeflow fan selection guide introduces the range. The Fumeflow D250 and Fumeflow TD250 have their own performance information. Choose between models using the required duty and installation arrangement, not a presumed like-for-like substitution.
Confirm whether accessories, controls and electrical work are included in the quotation. A change of motor technology or speed control needs a compatible design and a documented operating sequence.
Plan the changeover before ordering
Agree the shutdown window with everyone whose work depends on the extraction. Plan process clearance, safe isolation and any decontamination before the old fan or duct is opened. Access arrangements should account for equipment weight, roof work, lifting and protection of the occupied building.
Check the proposed connection positions against actual site dimensions. Allow for supports, flexible connections where specified, access to the motor and future maintenance. A larger motor or different outlet arrangement may change the space and electrical requirements even when the duct diameter is unchanged.
Use the installation review to address the cause of the original failure. For example, repeat overheating needs investigation of cooling and operating load, while unusual vibration needs a mechanical and system assessment.
What the handover should contain
Ask for the selected model and duty, installation details, operating instructions, maintenance requirements and the results of the agreed checks. Verify rotation, electrical protection, control operation and achieved extraction performance through the appropriate competent people.
Update the equipment register and drawings so future maintenance starts with the installed arrangement. For a fume cupboard system, coordinate the necessary commissioning checks with the person responsible for its use. Replacement is complete when the system is ready for its intended work, not simply when the motor runs.
Your questions
Can a replacement fan use the existing duct connections?
Sometimes, but dimensions alone are not enough. Confirm airflow, pressure, chemical compatibility, orientation, supports and maintenance access before ordering.
What determines the replacement cost?
The selected fan, controls, electrical changes, access, removal and commissioning scope all affect the quotation. Send the duty and site details so these items can be considered together.