Manufacturer heating / controlled indoor ventilation wanted

You only need one CO2 sensor centrally in the exhaust air to use the information.

I just finished my first CO2 sensor. Why do you only need one centrally in the exhaust air? Because that gets the mixture from all rooms, but you want to know the worst room? Or am I thinking about it wrong?

The background is that you can't control the rooms individually anyway, so the information doesn't help you much, at most to manually adjust the flow rates with the forward temperature, but then a €100 device is enough to check the rooms.

I just finished my first CO2 sensor. Why do you only need one centrally in the exhaust air? The mixture of all rooms comes there, but you want to know the worst room? Or am I thinking incorrectly?

Your line of thought is correct. Usually, the value in the bedroom is particularly interesting. Of course, you can only turn up the entire system, but that's not a problem initially. Especially at night, the overall value is only semi-relevant, since it’s about the air in the bedroom.

The idea is not correct. Especially at night, you don't want to turn up the system because only one room exceeds a limit. Consider the volume of the system. In general, the topic of CO2 is overrated. What insight is supposed to result from it? Ventilation systems are designed to keep the indoor air in a healthy range. There is no need to regulate anything based on that. Ergo, no need to measure anything for it either.

Well, I’d say... my system is also only quietly audible on the highest setting in the bedroom. Not louder than a ticking clock.

I have two VOC sensors and one CO2 sensor connected. One VOC sensor is centrally located in the device, one in the kitchen, and the CO2 sensor in the bedroom. The system then regulates itself all the time.

And if you want to take it to the extreme, you could install ventilation with variable volume flow controllers. But yes, actually nonsense, I agree... it works perfectly fine like this and one sensor in the exhaust air duct should be enough.