DraftMax Basic Spare Parts FAQs
Straight answers to the questions people ask most when finding and fitting spare parts for a downdraft extraction table.
Which parts of a downdraft table wear out or fail most often?
The parts that work hardest are the push buttons and switching elements, the relays and contactors, the fuses, and the fan motor with its fan wheel. Control components fail from heat, vibration, dust and repeated switching. Fuses blow when something else is wrong, such as a motor drawing too much current.
Mechanical items such as adjustable feet can also be damaged by moving the table. Keep a note of what has failed, because repeated failure of the same part usually points to an underlying cause.
Can I fit electrical spare parts myself?
Only a competent person should work on the electrical parts of a table. That means someone with the training to isolate the supply safely, prove it is dead, work on the control circuit and test the unit afterwards. If your workplace has a maintenance electrician, they are the right person.
Always isolate the table at its main switch and lock it off before opening any cover. Follow the wiring diagram in the manual, and have the unit checked before it goes back into use.
What does a thermal relay do and how should it be set?
A thermal relay protects the motor. If the motor draws too much current for too long, for example because the fan is jammed or a phase has dropped out, the relay trips and stops it before the windings overheat.
It has an adjustable current range, and the setting should match the full-load current shown on the motor data plate. Setting it too high removes the protection, and too low causes nuisance tripping. Always choose a relay whose range covers the motor's rating, and leave the setting to a competent person.
What is the difference between normally open and normally closed switching elements?
A switching element is the contact block behind a push button. A normally open element completes the circuit only when the button is pressed, which is the usual arrangement for a start function. A normally closed element breaks the circuit when pressed, which is the usual arrangement for a stop function.
If you fit the wrong type, the button will do the opposite of what its label says. Check the existing element before you replace it, and test the stop function carefully.