How to automate mechanical ventilation device (Helty FlowPLUS - FlowELITE)?

I’m pretty new on the Home Assistant world (I just started experimenting since couple weeks).

The mechanical ventilation system makes it possible to control the exchange of air in the building, without having to open windows and avoiding unnecessary dispersion, thanks to the heat exchanger that allows the recovery of energy otherwise dispersed outside.

I have a MV device that is not smart-ready, it only has a smartphone app that can control it, but it works only when the smartphone is connected to the local Wifi, it does not even have the cloud capability to control it from out of home.

I want to understand if there is a possibility to create a sort of custom integration for HA so that I can control it and access the sensors of it (it does have sensor for umidity, co2, …)

I asked the manufacturer about smart compatibility and he confirmed me that there is nothing available or even on plan, the only suggestion he made is to try leverage on the “Modbus” port on the back of the device.

This is the image of the port
And I also have a PDF with the documentation for the port:

I was wondering if there is some sort of external device which can act as bridge between HA and sending inputs to such port. Or else, if there is a way to determine somehow how the smartphone app interact with the device and try to replicate it on HA.

Of course a more simple solution can be using something like a smart plug and controlling on and off, but with this I won’t have access to all the sensor data.

I understand that whatever will be the solution, some coding will be required, but this may be a second step. Right now I’m trying to figuring out the basic approach for this kind of scenario.

Thank you

Looks like a job for ESPHOME. You get a lot of information bij Googling for “modbus esphome”

Required hardware is inexpensive (like €20 in total)


it looks like an Helty Flow VMC (or MEV) to me…

I have just built a custom circuit using NodeMCU and Modbus interface, communicating to the device via modbus RTU and publishing the states into MQTT. Commands for moving from speed A to speed X are also available via MQTT as well. I am in the process of writing a post, describing how it works and how to build it. Hold on please.

Hi svalmorri

Yes, it is Helty Flow VMC. The manufacturer provided the PDF manual with the schematics I shared.

While I very new to all the HA world, I’m finding the learning curve more difficult than expected.
In any case I can see you are writing a post, so thank you very much in advance for your help.

During the time from my first post, I found 2 third party projects (which are relatively recent) about this brand:

I’m sharing my discoveries to you but I haven’t put my head in it yet, mainly because I’m still waiting for the device to be mounted in my home but also those modules seem to be a bit too much advacend for my current knowledge of HA, but maybe they can useful to you.

These 2 projects seems to both leverage on a software approach, emulating the commands that the mobile app can send, in this case I’m not seeing a use for an external hardware controller.

Here is my implementation of Helty Flow VMC to HA:
Alpac Helty Flow VMC - The modbus way - Share your Projects! - Home Assistant Community (

Hello Nicola_s, let me know how you’re doing with the code:

If you need any assistance, feel free to contact me! :slight_smile:

Hi @nicola_s,
Did you receive any additional information from the manufacturer regarding the Modbus connection to the VMC?

Thank you!