Quick answer
The right choice depends on the confirmed fault, the condition of the equipment that would remain, compatible parts and the work needed to restore dependable operation. Ask for a diagnosis and clearly scoped options. Comparing the installed outcome, access needs and likely disruption is more useful than comparing a motor price with a complete replacement price.
Why a stopped fan does not settle the decision
An exhaust problem can lead to several different repair proposals. Before choosing one, ask what has actually failed and which findings support that conclusion. A quotation for a replacement component should explain the component and the work included; it should not leave you to assume that every other part has been assessed.
Separate the confirmed fault from concerns that need further testing. If a system has also been noisy, difficult to start or poor at extraction, make those symptoms part of the enquiry rather than treating them as unrelated.
Three scopes to discuss
A targeted repair addresses a defined fault while retaining the equipment that remains suitable. Ask which findings support retaining it and what the repair does not address.
Motor or drive-assembly replacement changes more of the equipment. Ask how the replacement will be matched to what stays, whether associated controls need attention and what checks are included after the work.
Complete fan replacement is a different scope again. Ask why the assembly is being replaced, what modifications or access work are needed and which existing system limitations remain outside the quotation. A new fan does not by itself establish the condition of the rest of the ventilation system.
Compare the complete scope
Use the same questions for each option:
1. What fault or condition is this option addressing?
2. What equipment is retained, replaced or excluded?
3. What is known about compatibility and parts availability?
4. What access, isolation and associated trade work is included?
5. What testing and handover information will be provided?
6. What downtime depends on parts or site arrangements?
7. What further assessment or rectification may still be needed?
Keep cost comparisons specific to the actual quotations. This guide provides no price range, savings promise, warranty term or claim that one option is always cheapest.
Questions before approving work
Can I replace the motor only?
Ask for the findings that support keeping the rest of the assembly and the proposed matching and testing scope. A motor-only quotation should make its limits clear.
Does a VFD remove the need for mechanical repairs?
Do not treat a drive retrofit as a substitute for diagnosing an existing fault. Ask why it is recommended for that particular system and what separate repairs are still required.
Will a replacement solve poor extraction?
Ask whether poor extraction has been assessed as part of the proposed scope. Avoid assuming that changing one component answers every airflow or capture problem.
How can I help the assessment?
Describe the symptoms, history and recent changes. Provide existing photos or records if available without accessing hazardous areas or opening equipment.
Next step
Request an exhaust fault assessment and discuss the practical repair and replacement options for your existing system. Ask for clear findings before committing to a larger scope.