Hello all,

I have a question about the VM148 thermostat:
I will be using the VM148 as an outside sensor for my central heating installation.
It will be monitoring the outdoor temperature, and prevent the indoor thermostat from starting up the heating before the outside temperature dropped below +20 degrees Celcius.

Nothing too exciting thus far. As long as the outside temperature is below 20 degrees the relay of the VM148 will connect the indoor thermostat and heating will take place as soon as the indoor thermostat is triggered.

However, outside temperatures can drop under -18, below the VM148 lower range, putting it in the “UnFl” error state.
What will be the state of the relay when this happens?
Will the relay be deactivated, and in my situation, disable heating all together? Not very funny at minus 18 degrees :slight_smile:
Or will it stay being activated, regardless of the underflow error?


We are afraid that the relay will be turned off during underflow or overflow, for safety reasons.