I bought a Shelly Dimmer 0/1-10V PM Gen3 and the Shelly Plus add-on, so I could add 4 temp probes to the supply/exhaust feeds. The wiring was surprisingly easy. Wire your mains input to L and N and split the N to also go to your MHRV unit. Then wire up output 0 to the unit live input and the Shelly switch will control on/off power to the unit.
Then wire up P1 S to the positive output of the 10V and the negative to the P1 - terminal and you are all set.
You will also need to go into the setup menu and select Proportional 1 to be Pure 0-10V. I also set the fan low speed to 10% and high to 80% so that the Shelly has more control of the fan speed. I think the default setting was 30% and 70%.
Also just posted my air quality monitor project if you’re interested to control your VentAxia with HA using indoor air quality index, Co2 and humidity levels etc. This is now what drives my unit on/off and fan speed.
With RS232 in mind, could all this be avilable through a rs232 to ethernet converter and your clever plugin/app to HA?
I don't have any soldering nor progamming knowledge but I have just connected my solar inverter via a RS485 to ethernet adapter using someone elses app in HA with good results.
It just seems like a straight way of doing it, but I am clueless when it comes to HA and writing software.
Does anyone know if there are any diagnostics available on the summer bypass status? I'm not sure ours is working correctly.
We are currently experiencing a heatwave in the UK, and I've noticed that even with the summer bypass on, the outlet temperature feels colder than the supply to the house (using mk I hand thermometer on the metal pipes). Because we have a ground/air heat exchanger on the inlet side the inlet temperature can be quite low even when it's hot out, so we set the incoming air temp limit to 12C to ensure the summer bypass stays on (internal target is set to 21C).
Using the built in diagnostic mode I can see the incoming air temp was 18C (despite external air temps being north of 30C - ground/air heat exchanger FTW), with room extraction at 27C.
But still the extract pipe was noticably colder than the room supply, which suggests the heat exchanger is still "in circuit".
Is there any way to physically check if the bypass is active? (Even when we've had the thing open for heat exchanger maintenance I've not been able to spot where the bypass actually is!)
Answering my own question in case it's of benefit to anyone. The bypass is on the right sat between the heat exchanger and external inlet fan. The actuator pushes against a mechanism that closes the louvres covering the heat exchanger, and open the ones into the space behind and in front of the heat exchange matrix.
This allows the incoming air to take the direct path to the house supply outlet instead of via the heat exchanger (and similarly the house extract direct to the external outlet).
I extracted both the heat exchanger and bypass and gave the latter a through clean as it had ~10 years of accumulated dust (post-filters, so not too bad).
I was able to observe it opening - slowly, and maybe not quite fully? But it did little to affect the air temperatures at the different in/outlets
External air temp was around 29-30C. Inlet was 21C (cooled by ground/air heat exchanger). House supply and extract both around 29C, and external exhaust was around 25-26C.
All spot-readings with an IR thermometer pointed at post-it notes on the metal spiral duct (otherwise you just get a reflected reading from the surroundings). Not exactly scientific. I really need to get some PT1000s or DS18S20s on them to log the temps in HA...
On my system I also struggle to know if the summer bypass is working. More important though for me is that the inlet vent on the south roof sucks in really hot air in heatwaves as it a black slate roof. So it's better to just turn off the system to stop it sucking in this hot air. I need to install an alternative inlet on north roof but even this will get solar gain when the sun is high in the sky.
Interested to control the unit from HA.
I am currently at something similar. But I wanted to control bypass with Shelly’s O(utput) too. Unfortunately, this Shelly does not work independently, sice it is light controller, and when O is off, also there is no oputput in 0-10 DC. So I’ve added another Shelly (1PM) to control just the bypass.
I get inspired in vent-axia manual about their “IR” controller wich is using some “CIB protocol” (no idea here). Bypass is controller by simple relay on main board that sends L to it, so Shelly 1PM is good for this.
However my settings of fans are bit different- according to CIB installation manual - low 1%, normal 10% (however they said 15), high 100%. Shelly dimmer is set to work in 0-10 range, with 5s transition.
That way I am using 10 % “brightness” as standard low, which is around 900 rpm. I am not sure what is safe minium, although when “light” is off, it falls back back to units low 1% mode (since I got also normal mode in schedule) wich is around 350 rpm. SW on 1PM is used in detached mode only to monitor if unit wanted to open bypass, however it settings it is OFF now, since i got own control.
Also I’m still using original forked repo on ESP2866 + RS232 to TTL to read display and press buttons remotely if needed.
Currently I am pretty happy with this and planning automations for “smart” home features.
I’m currently working on my version of the controller where I want to add 4 independent calibrated PT1000A temperature sensors via Modbus to the whole build for the intake and exhaust channels. I am gonna use an op-amp to go from a PWM output to a stable 0-10V output. And the ESP is hard-wired with Ethernet.
However, I’m at the stage of soldering everything together and building my code in ESPHome. I’ve noticed the pull request on a custom component of @tardnuk, but it’s not merged or reviewed yet. And I’m not sure how to integrate the UART logic into ESPHome. Anyone got a lambda inside ESPHome? Or is this custom build neccesary when I view the original code repo
Hello,
I have connected the controller from Vent Axia looks very similar to the one you have on top.
Well done.
I was really interested in the humidity & Temp value. Let me know if these data are easy to pull every 10 min
