Setting flow temperature for gas heating in old building

Good day and hello everyone!

Since I am currently dealing with the topic "heating," I am asking the experts / experienced homeowners here :)

Briefly about the current status:
The house is from 1981 (slight insulation in the walls, mostly newly insulated in the roof slopes)
Basement floor heating
Upper floor radiators (except bathroom, since it has floor heating)
So two heating circuits

Heating system (condensing boiler approx. 15 years old)
Junkers Cerapur zsb 22 3
Control in the basement on the device via the FW 200
I have already replaced the pumps with high-efficiency pumps

I am currently trying to read up on the topic because I want to run the system more efficiently.
As far as I know, the previous owners left everything in the standard settings from 15 years ago.

In my opinion, it is most sensible to lower the flow temperature, or am I on the wrong track?

With the control unit, I can only set the max design temperature and the flow temperature.
Each per heating circuit.

Does anyone know the system?
I am grateful for any help!!

Regards

Without hydraulic balancing, the simplest method to optimize the flow temperature (regardless of the system) is: Turn all radiators fully on (5). Gradually lower the flow temperature step by step. Continue doing this until the coldest or hardest to heat room reaches the desired temperature (this will certainly take a few days). Then you are already very close to the optimum. In the second step, it is best to familiarize yourself with heating curves and adjust according to the outside temperature. In any case, lowering the flow temperature is the most effective way to save costs.

Without hydraulic balancing, the simplest method to optimize the flow temperature (regardless of the system) is: Turn all radiators fully on (5). Gradually lower the flow temperature in steps. Continue this until the coldest or hardest-to-heat room reaches the desired temperature (this will certainly take a few days). Then you are already very close to the optimum. In the second step, it’s best to familiarize yourself with heating curves and adjust according to the outside temperature. In any case, lowering the flow temperature is the most effective way to save costs.

Yes, thanks. That’s roughly how I planned it. Could it be that with this device you can only set the design temperature and flow temperature? Could it be that I might damage the system if the values are set too low, like constant cycling, turning on and off, etc.? Regards

I don't know the device, so I can't say anything about the setting options. Depending on the system, you can make it more detailed or more rough. I can determine the heating curve based on a (virtual) room temperature value (which determines the supply temperature) and the offset (a factor by which the supply temperature should be raised for every degree of outside cooling) on my system. In my opinion, the design temperature is the temperature that should not be fallen below on the coldest day.

Basically, you can't really break anything at first. It's okay that the heating cycles on and off. It just shouldn't turn on 10 times per hour. By lowering the supply temperature, I have at least achieved fewer cycles in my case. But there are other factors at play as well; I don't have enough specialized knowledge about them.

PS: Search online for the operating manual for the FW200. On page 52, you will learn more. You need to enter the expert level of the device (usually there is a standard code for this), then you can even adjust base points and other parameters. Nevertheless, read up on heating curves first before you start adjusting values in detail. When you begin, you need patience: Each change only shows its effect over the days (also varying depending on the weather). Additionally, I would document everything well, so that in case of doubt you can revert to the original values that work for you.