Posted by: @jeegnesh

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so this is on Valiant aroTHERM and my settings has the the room temp mod now set to inactive, so essentially no thermostat, hence my question what the timer is for

The timer is for if you are in expanded mode the wc is modified by switching off the heating if it’s too warm. You can have a set-back temp overnight or other period with a lower temperature for a certain time.

The other mode is active which is wc plus aiming to a set temperature (ie like ‘normal’) and that is for certain times.

If I am in inactive mode, then how or when does setback kick in?

Timer mode lets you specify a time and a temperature but as inactive the temperature for sure has no input.

@jeegnesh Doesn’t matter which room temp mod mode you’re using; the following behaviour happens:

During scheduled ‘heating’ periods, the heat pump targets your chosen set point temp. 

During scheduled ‘off’ periods, it targets your chosen setback temp. 

So this is it, what is my chosen set point, how does it get that? Considering the Room Temp Mod explanation and mine is set to Inactive.

• Inactive

  The thermostat is only a display, and the heating circuit is not being used 

   

   
• Active

  The thermostat adjusts the flow temperature based on the difference between the room temperature and the indoor target. For example, if the room needs more heat, the system will increase the flow temperature. 

   

   
• Expanded

  The thermostat acts as an on/off switch for the heating, turning it off if the room temperature is exceeded. The system control also regulates to the target room temperature, regardless of the outdoor temperature.

@jeegnesh Your chosen set point temp is the desired indoor temperature that you choose via your SensoCOMFORT controller and myVaillant app.

If you’re finding that your house doesn’t drop in temp enough to hit your chosen setback temp during the scheduled ‘off’ period, then this means that either your weather comp curve needs tweaking, and/or you should select a lower setback temp. 

@ectoplasmosis so it constantly breaches that number and turns on.

I do know if I switch to expanded then it adheres to that temperature. So I guess I am asking what inactive does

@jeegnesh It’s all been explained to you already. 

Inactive is pure weather compensation mode, where the only sensor which affects flow temperature and thus heat input into your house is the outdoor temp sensor. There is no longer a concept of an indoor thermostat. 

If your system is overshooting your chosen set point temperature, then your weather compensation heat curve setting is set too high. Lower this setting, wait a couple of days and see how your house reacts. This is a process of trial and error, and takes time to end up with the perfect curve setting which suits your particular house. 

Make sure any TRVs etc are fully open. 

@ectoplasmosis perfect this now makes total sense to me.