Opentherm Gateway - Thermostat Temperature Messurement Diff

[roeland]

Hi,

I have recently placed a Openterm Gateway between my CV (Intergas) and Thermostat (Chronotherm Modulation). Technically this all works.

However, there is one strange thing.

When the Opentherm gateway is in between the CV and Thermostat the recorded room temperature is ~ 1 degree Celsius higher than without the gateway in between.
I have checked the voltages on both the CV and Thermostat connections and these are similar.

This behavior is repeatable by removing and replacing the gateway.

Any an idea what could cause this behavior?

[roeland]

I monitored the behavior a bit longer.

It seems that the temperature measured by the thermostat seems to be bouncing up and down. (See attached screenshot of the graph.)
This behavior is reflected on the thermostat screen. When i remove the OTG, the measurement is constant.

Anyone an idea what could cause this?