Oké, one step further with new challenges 
The Setpoint is now around 30 degr. But within a few seconds at 15%, the water temp shoots over the setpoint to around 40 degr, after which the boiler reduces power to 0%
Any idea?
Yes everything looks pretty good!
Moreover go to System Configuration → Duty cycles per hour and change it to Normal ( 3x per hour ). Then the duty cycle intervals during Low-load Control will be 20 minutes instead of 15 minutes ( 4x per hour ).
Thx, ill do. But is the behaviour in the graph above correct then? It doesn’t look like to me…
No it is not correct, you are right. Do you have the WiFi version of OTGW or the serial?
I have the wifi version
I see a lot of disconnections. This is a known issue when you have the WiFi version and use the serial connection. Better change to MQTT, rock solid connection
So now the flame is ON for let’s say 5 minutes and 15 minutes is OFF and the relative modulation is 0% during the ON time? Or the Control Setpoint value is still low and the boiler is cycling?
Hi,
What happens during the on time:
Setpoint set at a certain vallue, let say 30 dgC. After a few seconds the boiler switches on and starts mudulating for a few seconds. When de actual temp is raising, the setpoint changes directly to a vallue 2 degr. under the actual temp and is keeping this delta for a few minutues. In the meamwhile, the modulation is going back to 0% within a minute.
After a few minutes the setpoint goes back to 10 deg C
See graph
This is completely normal SAT behaviour. Low-Load Control is active, and SAT is intentionally operating your boiler at its lowest stable modulation to avoid overshooting and to maintain smooth, efficient control.
Oh thats good to hear. Only issue remaining is that it does not warming up my room (setpoint thermostat is 19,5 and act temp is 19). This might be a setting of the SAT which I might to adjust?
Max setpoint 40
Coëfficiënt curve 1,5
Minimum setpoint adjustment factor 0,2
I have a very well isolated house
Yes, you need to use a higher Heating Curve Coefficient in the General settings.
Thx!!! I’ll ow you a few coffee 
Hoe do you determine the optimal vallue, or what is a good vallue to start with, 5, having a well isolated house?
Better start with the value 2.5, if your home needs more then slowly use a higher curve until the room temperature is on setpoint.
It seems to work, I’m just tuning a little bit, the system is using a little bit to much gas compared to my previous thermostat. A few remaining questions:
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During the night, with the temp outside decreasing, the SAT is showing strange behaviour, see picture. The setpoint is below the actual temp, so there is no heat required, but the boiler is constantly cycling (and using gas). Any idea what triggers this?
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I would like to use my old thermostat to adjust the setpoint. Do I have to select this thermostat in het thermostat and or the primary field? No TRVs involved.
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How long does it take the thermostat to ‘learn’. Does it have a long term memory or is it based on the last minutes/hours?
Looking forward to your respons!
Cheers
This is strange behavior. Normally shouldn’t perform like this. Can you give me some more informations?