Vitocal 222 & Vitotronic 200 - heating based on actual room temperature

[Johan2]

Hello! My German is not great hence posting in English. Hope someone can help.

I have a Vitocal222 with Vitotronic 200 integrated in the indoor unit located in garage. There is an outdoor temperature sensor and I can set desired temperature via Vitotronic. Currently heating happens based on difference between outdoor temperature and desired temperature set via Vitrotronic. I would like to change to: heating based on difference between actual room temperature and desired temperature. What is needed to make this change?

Do I need to purchase another Vitronic 200 (or other component?) and place it in living room?

Change in Vitocal 222 settings required?

Thank you & best regards

[koektrommel]

Hi Johan2, if I may ask, why do you want to make this change? Don't you manage to get the right room temperature based on your current setting of (pure?) weather control? If this is indeed the reason, then the next question is whether you have already tried optimizing your heating curve. Didn't this work out as you wanted? Why not? Could you explain?
If you insist on changing the settings and you don't have the advanced Vitotrol, you have to ask your heating firm to make the required changes.  If you have the right Vitotrol, you can make some changes yourself but I don't know exactly which parameters are involved.
However, I think it is worth trying to optimize your heating curve before you switch to a different control mechanism. If finetuned properly, weather control often results in a (more) efficient way of heating your house because you can select the lowest water temperature to achieve the desired room temperature. 
As a meet in the middle between pure weather control and pure room temperature control you could allow for room temperature influence. This means that the heating curve is adjusted according to the difference between actual and desired room temperature. Unless you have a Vitotrol I think your heating firm should make the required changes for this.
FYI, I have a Vitocal 200s but cannot change the parameters to make a switch from pure weather control to a different control mechanism. I would need a more advanced Vitotrol for this I was told. This is not necessary though, because in my case weather control works perfectly after I finetuned the heating curve. That is, with my current heating curve, I get the desired room temperature regardless of the outdoor temperature and I use the minimum possible water temperature. In this way, I get a high COP and thus save money on electricity costs. But it probably depends on your specific situation weather this is feasible for you too. I have a renovated and very well isolated 150 m2 house from 1993 with floor heating only.

[Johan2]

Thank you very much for your reply. I am not able to get the house to a comfortable 21 degrees by changing heat curve settings. It’s either too hot or too cold. I have floor heating at ground floor and low temperature radiators in 1st floor bedrooms. I feel heatpump is running too many hours using  too much electricity hence wanted to switch to room temperature control. It should be possible with Vitotrol 200.
The other challenge is that my installer is out of business and I contacted several other  installation companies but they all say they don’t want to work on it because they didn’t install the heat pump. It seems I’m stuck☹️

[koektrommel]

Dear Johan,

I can't help you with the Vitotrol, but I do have an advice for you. Instead of switching to room temperature control directly, it could be beneficial anyhow to check whether your heating system satisfies some basic requirements. This could save you energy costs, even if you eventually decide to switch to room temperature control. 

Without a full specification of your heating system it a bit of a guess for me, but I have the feeling the following could be part of your problem. If you have both floor heating and radiators, you need different flow temperatures for both (lower ones for the floor heating and higher ones for the radiators). To say more I need some information:
* Do you have a heat pump that allows for two separate heating circuits for floor heating and the radiators, each with their own heating curve? Or do you have a floor heating mixer that produces less warm water for the floor heating and uses the undiluted warm water for the radiators? 

*Have you opened all radiator valves to the fullest instead of using them to control the temperature in your rooms? For the proper running of the heat punp this is crucial.
* Furthermore, has your heating firm implemented a hydraulic balance with your radiators? Also this is very important for a heat pump to function properly.
If you give more specs of your heating system, I may be able to say more.