Ventilation Systems ComfoAir CA350/CA500 Control for HASS (Zehnder, Storkair etc.)

I am controlling my CA350 Luxe ventilation system over RS232. I hacked an esp8266 (eps-01) chip together with a cheap step down module (12V to 3.3V) an a super small RS232-to-TTL module. Wrapped all parts with some shrink tubes and now it hides behind my CCEase controller in the wall. It’s powered directly from the ventilation system.

This setup provides me with a telnet server on the esp-01 to have a transparent wifi-to-RS232 bridge. I can send commands from my Linux box to my CA350 or use my simple python script to turn things on an off or read some data. E.g. I can read firmware version and temperatures and write the ventilation levels from 0 to 3 (off to high). With this it’s easy to setup some HASS switches etc. to do basic things.

I did a lot of research and came to the point where I understood that I am not able to write a good component for HASS. I’am far a way from being a programmer or engineer. It makes no sense to invest more time to create a half-assed version of something that needs a solid base.

I want to provide as much information about my setup and the CA350 / 500 and it’s protocols as I have gathered to you.

What the home assistant community needs is a programmer that has the time and the passion to create a solid component. Is someone out there?

Here I will list all links / photos / infos I have:

Related ventilation systems:
StorkAir WHR950
Comfoair CA350
Comfoair CA500


Open problems concerning Hardware:
How to switch CCEase off and esp-01’s RS232 module on by esp-01?

Open problems concerning software:
Someone there to write a component?
Commands to control exhaust and intake air ventilation separately?

CCEase (Controller)

CA350 ventilation system

I will clean up this post as soon as I have the time to.
Pictures / schematics of my setup (esp-01, stepdown,RS232-to-TTL) will follow soon.
Sorry for now!

My CC Ease Controller (12V) is down.
No display, no controlling functions.
Can You recommend how to replace it or fix it.
I use it for Zehnder Comfoair 550.

Will new Comfosense C work with my Comfoair 550 ?

Thank You for response.

First you can try is to disconnect the CCEase completely (unplug it). Wait for 10 sec or so and try it again.

Second you can try: disconnect your comfoair completely from power. Wait a minute or two and power up your ventilation system again.

What exactly did you do before? CCEase takes damage if you wire it up the wrong way… Especially +/- in reversed order for a too long time kills parts of CC Ease.

Do the buttons still work?

Thank You for Your time.

The suggestions did not help.
I have powered off comfoair completely for 1 hour for cleaning and then controller did not start again, after powering comfoair.
I did not change cables.
I did not open it.

Display is dead.
Also when I press buttons comfoair is not changing the speed.
I guess power supply or processor are down.


I can buy at good price (100USD) used controller Comfosense C67 mtb.

I have got email from Zehnder that it will replace my old Comfocontrol Ease for my old Comfoair 550 Luxe.

But I’m not sure beacuse some people say that new Comfosense C is compatible only with new Zehnder q450, q 600 and it is not compatible with old Zehnder, which use CanBus, and do not have display.
What do You think ?

Here is picture of my old connection of ComfoControl Ease :

There is volatge between white cable (gnd) and brown (12V) equal 12V DC.
There is no volatge on other cables.

In the manual of new Comfosense C 67 mtb :
there is a drawing with connections between :
Comfoair : Comfosense
12V : 12V

I guess I should connect :
old 12V to new 12 V
old gnd to new gnd
but how to connect the last two :
green to H ?
red to L ?


You should check with a multimeter. Do you get +12 on purple/violet and white? If you get -12 then they are reversed. This way your display may get damaged (happend to me…).
Green an Red are for communication. If you plug them in in the wrong way, you get an error on the display. just reverse them then. This should not damage anything.

If you connected purple and white correctly the display should instantly light up. If you checked that there is +12V (purple +, white - ) and the display does not light up, then there could be two problems:
-display is distroyed

  • a fine-wire fuse / microfuse is destroyed on the board of your CA.

A destroyed fine-wire fuse happend to me once also.They look like this:

Could you provide some good pictures of all (three?) PCB of your CA?

Yes, there is 12V and display does not light up.
Fuse on CA is ok.
I attach picture of PCBs of controller CC Ease.

I cannot add more pictures as new user.
I have been told by servis that CC Ease can be replaced by Comfocontrol.
But - it will NOT work with latest Comfocontrol C series which will work ONLY with new ComfoAir Q series.
I have ordered Comfocontrol.

1 Like

I have purchased new controller Comfosense 67 (not Comfocontrol).
It has fully replaced old controller ComfoControl Ease from 2008.
Be careful : newr version Comfosense C 67 will NOT work with older versions of Zehnder Comfoair.
I have connected it as at attached photo.
One can compare colours with old connection of ComfoControl Ease.
To access advanced menus (Geothermal Heat Recovery, fan speeds) one has to put password. Mine is : 14
Thank You and good luck.
I do not know how to get inside Comfoair to make photo of circuit board.

if you are still interested in control your ComfoAir by PC: I expanded the openhab.binding.comfoair (originaly written by Holger Hees) with many new read and write commands, so now you can have full control on your ComfoAir like as by original contol panel CC Ease or CC Luxe.


If you are interested I’ve taken the comfoair component created for Domoticz integration and adjusted it for Home Assistant. It is still early and quite dirty work but feel free to use and built upon. Would be greatfull if you keep it public or directly contribute to my repo.

1 Like

Hi, I have only the ComfoAir 350, no panel. So I just have to connect the RS232 on the ComfoAir350 and on my Raspberry Pi with an RS232-USB Stick? Sorry but I am a beginner…

Finally had a moment to get my esphome comfoair plugin working, you can find it here:


For clarification; like @linuxlurak my esp-01 is powered by my WHR-950 and is natively communicating with home assistant. The board contains a 3.3v regulator, esp-01 and a max3232, all sourced from aliexpress. I should probably have bought an original max3232 as these are known to be counterfeit, we’ll see how long it will last…

Oh, and here is the mess on the back:

Nice hack! Are you using a CA-remote? I noticed some problems when the CA remote and my eps-module communicated at the same time. I implemented two optocouplers to connect/disconnect power and TX/RX from CA remote while communicating with it. I’ll see if I find some pics of the module and the PCB. I could share the pcb gerbers/schematics too.

Are you using a CA-remote? I noticed some problems when the CA remote and my eps-module communicated at the same time.

No I’m not. I could add a (software) switch or an option when externally controlled to disable the CA-remote. Would you like to test this, once integrated? Or are you keeping your current software solution?

Today I added the simple thermostat view using a custom card from

Not there yet, but at least the control is a lot friendlier than before:

Just too give my 2c

I have a WHR-930 with a custom PCB that reads the serial input/output over MQTT. (Based on a Arduino MKR1000 WIFI with custom firmware) and a lovelace card based on with a custom python component.
Nothing public (yet?)


 a lovelace card based on

Nice one, I did a copycat on your card, it still needs some buttons though:



I was able to solder the board together yesterday and connect it to my ComfoAir, it was immediatly working :grinning:
Many thanks for creating this great ESPhome integration !
I have seens 2 minor things that we can maybe improve:

  1. the climate object has an object
current_temperature: 0

this always stays at zero, might be usefull the populate this with the ‘Return air’ as this value is compared with the setpoint comfort temperature.

  1. there is a strage thing with the off fan mode:
  - 'off'
  - auto
  - low
  - medium
  - high

don’t know why that one is quoted, but it seems to work.
Finally, what is the role of the auto mode ? For me this just seems to be the same ass off mode.