Central heat control - Stiebel Eltron WPC

[edoedo]

Hi all,

I'm thinking about purchasing a Loxone system for my house. But before I want to spend a lot of money I want to make sure my idea / target is possible.

I'm using a Stiebel Eltron WPC heat pump which I want to connect to Loxone by the ISG web device (modbus):

https://www.loxwiki.eu/pages/viewpage.action?pageId=24840030

I want to control the heat / cooling over 3 seperate linving areas: (All aeras have floor heating with one on/off valve for each level)
Basement, only heating after activation by app
Living room, heating / cooling
Bathroom and bedrooms, heating / cooling

I want to install a Loxone climate sensor on each level.

Does anybody has some experience with connecting the Stiebel heatpump to Loxone and the use of the correct buildingblocks? Or better a example project?

Thank you all in advance!

Regards,
Edo

[Jan W.]

Hi Edo,

I have a similar setup and written the modification to the ISG web pages to allow for easier integration into Loxone. My ISG web does not has a Modbus/TCP option for free, so I've choosen this path. With a new ISG web, the modbus option might be better, even if the documentation in the Loxwiki is not that good. There is a XML file for download somewhere in the doc - maybe it helps.

Initially I had the problem that the cooling option was only enabled in the heat pump after a FEK was connected to the heat pump! The FEK is a remote control unit(connected by a CAN bus cable), e.g. in the living room that includes a humidity sensor. I had a quick look and the FEK might have been replaced with the FEK 2 meanwhile. I recommend to read the manual for the heat pump (should be available online in english) and verify the prerequisites to enable the cooling option. The FEK might be more expensive than a cheap humidity sensor from China that can be added to Loxone, but on the other hand it is easy to install and your wife may like a manual knob to adjust some important settings. Stiebel Eltron does not trust "3rd party" humidity sensors, so there is no easy way to integrate them. The humidity sensor is used to stop the cooling if the air/floor becomes too humid to avoid any damage to your building.

It might be possible to "fool" the heat pump and write some code for a Raspberry PI with a CAN bus interface to connect directly to the heat pump (see links in the Loxwiki in section "Raspberry PI mit CAN-Bus Schnittstelle" - on the parent page to the link you have provided). If you are a good programmer, have experience with protocols like CAN bus and plenty of time, this might be an option for you, but otherwise I recommend to go the easy way and buy the ISG web and FEK.

In my setup the humidity and temperature from the FEK are used to set the flow temperature for the heat pump and give direct feedback to the control of the heat pump. The temperature sensors that I have integrated into Loxone (one for each room) are used to control the valves. To be energy efficient you should adjust the flow temperature directly. Closing the valves may help to distribute the heat within your house, e.g. if the sun is shining a lot, the living room might heat up, but not some other rooms to the north side. The "intelligence" within the Loxone system only shuts the valves if the desired temperature in the rooms has been reached, but it does not reduce the flow temperature of the heat pump. This is somehow similar to push the brake in a car, but still push the accelerator at the same time. The IRR (Intelligent Room Controller) in Loxone was neither made for energy efficient underfloor heatings or heat pumps.

So far I'm just monitoring the values that I get from the heat pump, but I do not adjust settings. It may be possible to fully control the heat pump by Loxone, but I'm not sure if somebody has done that so far. The intelligence and control of the heat pump by Stiebel Eltron comes from the outside temperature (north side without sun), some parameters about insulation and capacity to store heat within the house and feedback from the temperature that is returning to the heat pump. This works well and you are independent of a Loxone miniserver. I recommend to keep this intelligence within the Stiebel Eltron system and maybe use Loxone in the future to tune the system, e.g. by lowering some parameters if your weather forecast predicts sunshine for the next few days. As an example: If you have a house with a good insulation you may stop heating in the night before a sunny day.

Regards,
Jan

[orli]

Hi Edo,

I have a similar setup and written the modification to the ISG web pages to allow for easier integration into Loxone. My ISG web does not has a Modbus/TCP option for free, so I've choosen this path.
Jan

Jan, soweit ich weiß kannst du bei Stiebel ein (kostenfreies) Software Update für das ISG Web runterladen. In der letzten Version ist Modbus TCP enthalten.

[Labmaster]

Dazu muß das ISG Web aber auf einem Mindest-Software-Stand sein.
Das gebrauchte ISB Web welches ich gekauft hatte, war auf V4... da war ein Update nur über den Stiebel Eltron Service machbar, das haben die aber extrem schnell und auch kostenlos gemacht.
Ab da konnte ich dann die Updates selbst durchführen.

[Jan W.]

@Edo: Today I've updated the section in Loxwiki how to integrate Stiebel Eltron heat pumps via Modbus TCP, see https://www.loxwiki.eu/x/Xgd7AQ I hope Google translator is good enough to understand the content.

Hopefully there are other users who have done this method already and share their values and settings. It's quite easy to ex- and import XML files with all parameters.

Labmaster and orli: thank you for pointing me to the free update option for the ISG web! I had v8.6 and was able to do the update by myself.