Noisy fan

[Learjet]

I decided to switch to a variable PWM controller for the old fan that came with the house some 38 years ago. The old controller had a 5 position switch which went fast and faster. I wanted to slow it down more. The PWN controller was from Bunnings. It works but it makes the fan noisy, like a grinding sound. Worse on some settings than others and it gets noisier during the night. With the old switch there was no grinding sound. Suggestions?

[lsemmens]

Something in the back of my mind is saying, "capacitor" I remember the old fans in Darwin doing this and also getting slower and slower. I never repaired them so, cannot verify the accuracy of my analysis but I think, at one stage someone was replacing the capacitor in these fans and all was well.

[typan]

It may be 1050Hz ripple noise in the mains, the 1050Hz is a signal to switch on/off stuff like HWS switch yard comms. etc. Was your old wall controller a transformer type looking thing?

[Uncle Fester]

I decided to switch to a variable PWM controller for the old fan that came with the house some 38 years ago. The old controller had a 5 position switch which went fast and faster. I wanted to slow it down more. The PWN controller was from Bunnings. It works but it makes the fan noisy, like a grinding sound. Worse on some settings than others and it gets noisier during the night. With the old switch there was no grinding sound. Suggestions?

Remove the variable one and use the the old 5 position switch and add a capacitor in series to the fan. Try 2.5µF, this will make the fan run slower on all settings so that the max setting might be like the lowest 1st or 2nd setting of your 5 position switch. If too slow then use higher but from personal experience I like 2.5µF best. Fans give me a headache but the very light airflow with my mod is OK plus you will hardly hear it running at all.

Those dimmer type PWM 50Hz fan controllers will usually buzz with old fans and cheaper new fans too. It is not a fault. That is how they work.

Ripple signals (higher pitched beep not constant buzz) usually happen only twice a day/night for a couple of seconds. I am very certain that is not your problem.

Here is an example of the capacitor I mean. You can combine the two values parallel to get 4µF if you think it is too slow:



... and yes the usual find a licensed electrician to do this for you disclaimer.