VFD for air extractor filter

My fathers restaurant has a large extractor filter which I’d like to control with a VFD (Variable Frequency Driver). The extractor itself only has on or off, no speed control whatsoever.
The extractor uses 1400W at 230v, which is around 6A. (lets make this 10A, just in case).
I’ve been looking at the RobotDyn dimmer, but not sure if that will do the job. From what I’ve learned, motors will humm, lock up or fry when the wrong kind of dimming is used. And this being one serious expensive piece of kitchenware, I’d like to do it right :wink:
This brings me to VFD. Does anybody have any experience with this kind of projects? There’s plenty of circuits on the internet, but none of them are suitable for HA. I’ve seen some Arduino projects, but me not being a programmer would make this even more challenging.
Would be great if I could use the AC Dimmer component combined with some VFD, or other suitable device for controlling the speed of the extractor.
Any suggestions for off the shelf devices, or circuits that I can build myself?

After a quick peek on AliExpress I found this VFD, which looks very promising. It can be controlled by RS 485 and 0-10v, which makes this an internesting candidate :slight_smile:

The big difference between controlling LED brightness with PWM and a motor VFD is a LED strip is unlikely to kill someone!

VFD implies 3-phase mains power with significant currents, harmonics, phase angles, and complex power MOSFETs - really not something to tinker with unless those terms are very familiar. Yes, I am a cautious engineer!

That said, I’d expect even a cheap VFD module to be controllable via something like a serial port or dry contacts compatible with simple relays and an ESP module.

Single phase motors sometimes have speed control as simple as a capacitor or multiple windings so check what is installed - a 3-phase VFD could be overkill.

I’d start with a VFD module that works with your motors, then see how to interface with it - that way the hard power engineering is done for you. Concentrate on the user interface and automation, but don’t forget stuff like interlocking with fire alarms so flames aren’t fanned.

Just be careful as 3-phase motors have more kick…

Thanks for your suggestions and yes, high voltage makes me cautious :wink:
I found this on AliExpress, looks promising and not all too expensive to experiment with.


It’s the first one that I ran in to, so maybe there’s other more suitable for HA usage.
Looks like it already has RS485 built in, so can hook it up to an ESP32 or MCU. Not that I have experience with that, but worth a try I guess.
Oh, and the extractor is single phase, which makes it easier and slightly less hazardless :see_no_evil:

Not knowing the details, I would caution you on making any modifications to the air exchange in a commercial building.

  1. Disrupt the air balance (exhaust / make up). There are requirements for this balance in most jurisdictions in the US for ‘commercial’ property.
  2. You can put the motor bearings at risk (design depended) when changing the operational RPM envelop.

If this doesn’t deter you and you insist on upsetting the air exchange balance look at ABB, Siemens, or Eaton. I prefer ABB.

I’m afraid you guys make it a whole lot more complicated than it is. It is an extractor with a filter attached to it and I’d like to make it smart to be able to schedule the amount of air it sucks out. I.e. 100% when the kitchen is running, 20-30% during the night or when preparing for opening times. Thats it. Not’ going to change the airflow, fire alarms or anything like that. See it as a large fan speed controller, only one that is suitable for bigger loads (that sounds somewhat nasty :wink: ).
The one I found is suitable for single phase an can be controlled by 1-10v, just like many other devices. What I need to figure out is how to do that. If anybody can point me in the right direction, please do.

Esphome ?


I’m half way reading exactly that topic, thanks :slight_smile:

@ Holdestmade
You happen to have experience with Modbus? The VFD can be controlled by either 0-10v or Modbus. Which would you prefer? Modbus looks more complicated, but if its more reliable or flexible then I dont mind putting in a bit more effort.

No sorry, just did a search for 0-10v on Esphome

Ok, no problem.
Looking into Modbus because 1-10v only controls speed, while Modbus can do much more than that.
I’ll have to wait until the VFD arrives and see what commands are available. After that I’ll decide which solution suits best.

Just remembered, I have an esp32 running Esphome connected to my solar inverter using modbus so might be worth searching on here and Esphome website.

I just copied commands that someone else worked out.

I believe I saw that topic. Will have another look, thanks.
Which RS485 module are you using? Is the MAX485 any good?

Think it was one of these

HALJIA 5V MAX485 Module RS485 Module TTL to RS-485 Module Converter Board Compatible with Arduino https://amzn.eu/d/0J6FKaO

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