ᐅ Setting the Flow Temperature for a Gas Heating System in an Older Building

Hello everyone!

Since I’m currently dealing with the topic of heating, I’d like to ask the experts and experienced homeowners here 🙂

A brief overview of the current situation:
The house was built in 1981 (there is some insulation in the walls, and most of the attic slopes have recently been insulated)
Basement has underfloor heating
Upper floor has radiators (except for the bathroom, which has underfloor heating)
So, there are two heating circuits.

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

I’m currently trying to learn more about the topic because I want to run the system more efficiently.
As far as I know, the previous owners left all settings at the standard defaults from 15 years ago.

In my opinion, the most sensible thing is to lower the flow temperature, or am I mistaken?

With the control unit, I can only adjust the maximum design temperature and the flow temperature.
Each setting can be made per heating circuit.

Does anyone have experience with this system?
I’d appreciate any help!!

Regards

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

HausiKlausi schrieb:

Without a hydraulic balancing, the simplest way to optimize the supply temperature (regardless of the system) is: turn all radiators to the maximum setting (5). Gradually lower the supply temperature step by step. Continue doing this until the coldest or hardest-to-heat room reaches the desired temperature (this will definitely 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 them depending on the outside temperature. In any case, lowering the supply temperature is the most effective way to save costs.

Yes, thanks. That’s basically what I was planning.
Is it possible that with this unit you can only set the design temperature and the supply temperature?
Could it also be that I might damage the system if the values are set too low, like causing frequent cycling, turning on and off, etc.?
Regards

I am not familiar with the device, so I cannot comment on the adjustment options. Depending on the system, these can be more detailed or more basic. In my case, I can set the heating curve based on a (virtual) room temperature value (which determines the supply temperature) and the offset (a factor that increases the supply temperature for every degree of outdoor temperature drop). In my opinion, the design temperature is the temperature that should not be fallen below on the coldest day.

Basically, you cannot cause any damage at first. It is normal for the heating to cycle on and off. It just should not turn on 10 times per hour. By lowering the supply temperature, I have at least achieved fewer cycles. However, other factors also play a role here, and I have limited specialized knowledge about those.

PS: Try to find the user manual for the FW200 online. On page 52, you will find more information. You need to access the expert mode of the device (there is usually a standard code for this), which then allows you to adjust base points and other parameters. However, make sure to read up on heating curves first before you start making detailed changes to the settings. When you begin, be patient: Each adjustment takes several days to show its effect (which also varies depending on the weather). Additionally, I recommend documenting everything carefully so that you can revert to the original settings that work for you if needed.