I have managed to make Homey control the mechanical ventilation system in our home, Stork Air WHR 930 (WTW/HRV), by installing Xiaomi Aqara double relay LLKZMK11LM replacing the perilex plug. Homey can now control the 3 speeds of the installation.
There are other, more slick solutions available in this forum, but they all use Z-Wave devices. I have an extensive zigbee mesh network in the house, so I was looking for a Zigbee base solution. I could not find a Zigbee 0-10v dimmer, so I decided to use the Xiaomi Aqara double relay instead. It is quite easy to install.
Try it first by connecting a standard 220V plug to the N and L connectors. Put it somewhere in an outlet in the vicinity of the HRV and wait for a bit. Pair it to the Homey and try to open/close the relay. If this works, you at least know the zigbee network reaches the HRV unit.
Switch of the mains for the WHR 930 and open the system acooriding to the user manual, which can be found online. Open the plastic casing on top and remove the plug. You will see the N, live wire (going to L3 as well) and L2 and L1. Split the N and L3 and connect it to N and IN on the Aqara switch respectively. Connect L1 to L1 and L2 to L2. Stick the relay somewhere to the top of the unit so that the zigbee antennea can reach the plastic casing on top for maximum coverage. Close everything up the other way around. Wait a while for the zigbee mesh network to include the relay again and test the switches in Homey.
The unit will run at speed 1 when only powered through L3 (both Aqara switches off), It will run at speed 2 when L3 and L2 are powered (switch L1 off and switch L2 on) and ti will rund at high speed when L1 & L3 are powered or L1, L2 & L3 are powered (switch L1 on, switch 2 on or off).
I use a Netatmo weather station to measure CO2 levels (amongst others). You can find many flows on in the community to do something based on sensor values. This is what I used.
CO2 levels should be under 800 PPM normally, 1000 PPM occasionally and should reach 1200 PPM maximum. I used Better Logic to create a variable CurrentCO2, if it changes it updates and stores the previous value in a variable LastCO2. Then I created a Math.js formula using Better Logic to determine if the CO2 level is above 800 PPM and rising fast or it is above 1000 PPM. If that is the case, the HRV should start running on high speed. If CO2 levels are below 800 PPM again, the unit should return to running on Speed 2. Unless Holiday is true, than it can revert to speed 1.
Hope the above can help someone with the same ambition as me, to make things smart in the house. If you have any questions, please let me know. I am happy to help.