Plymovent MNF Spare Parts FAQs
Straight answers to the questions people ask most when choosing and fitting spare parts for mobile extraction fan units.
What is a motor protection switch and why would I replace one?
A motor protection switch combines a manual on-off switch with overload protection for the motor. It trips if the motor draws too much current, protecting it from damage.
If the switch is faulty, damaged or keeps tripping for no reason, it may need replacing. A tripping switch can also point to a motor, wiring or blockage fault, so investigate the cause first.
How do I choose the right setting range for a motor protection switch?
The switch must have a current range that covers the motor's rated current, which is on the motor plate. The switch is then adjusted to the motor's rated current.
A range that is too high gives poor protection, and one too low trips unnecessarily. Have a competent electrician select and set it.
Why does my unit keep tripping?
Common causes are an overloaded or blocked fan, a failing motor or bearings, a damaged wheel rubbing the housing, low or unbalanced supply, or a fault in the protection switch itself.
Isolate the unit and check for blockages and damage. Have an electrician investigate rather than simply resetting repeatedly or turning up the setting.
Why must motor and fan parts match my supply frequency?
Motor speed, and so airflow and motor loading, depends on the supply frequency. Motors and fan parts are often made in versions for 50 Hz or 60 Hz supplies, and UK mains is 50 Hz.
Using a part made for a different frequency can change performance and put extra load on the motor. Check the frequency on the data plate of your own unit and its motor, and make sure any replacement is marked for the same supply before you order or fit it.