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Hello Forum,

I have been using an Elga heatpump over the last 2 years. Since I installed a woodstove this summer and still wanted to heat the parts of my home that are not heated by the stove, I purchased a Honywell Evohome installation (with the opentherm option).
Connection the Evohome to the Elga makes the Elga start immediately and it never stops (until I remove power from the Elga).
Has anyone successfully conntected the Evohome to the Elga?
In the meanwhile I connected an Opentherm Gateway in between the Evohome and the Elga, but I am not able (yet) to have the Elga do what I want.
Has anyone (perhaps hansdegit) tried the opentherm gateway with the interface firmware to 'fire-up' the elga? What commands does the Elga exact need to start?
I have Raspberry Pi connected to the opentherm gateway and am planning to connect the conventional (gas) boiler using and on/off conection directly to the Raspberry Pi.
Any help is appreciated!
many thanks,

Eric

Do you have the EvoHome 1 (monochrome) or 2 (color display)?
I've had the same problem with the 1 version, though the R8810A (OT module) was not connected to an Elga but an ordinary boiler.
After connecting all modules together, it seems that the EvoTouch doesn't automatically recognizes the OpenTherm module, it remains as an on/off module. You must manually change this setting to OpenTherm. Not doing so, the boiler keeps on heating.

Haven't been here recently, sorry.

The Elga does not respond to CS commands, it only listens to room setpoint overrides. If you want to start the Elga, set the room setpoint 0.4 degr LOWER than the current room temperature. If you want to switch off the Elga, set the room setpoint more than 0.5 degree LOWER than the room temperature. That is, the Elga stops heating when the reported room temperature is 0.5 degr ABOVE setpoint.

The consumed power increases when:
- you set the setpoint closer to the room temperature
- the gap between hot & cold water is larger than 3 degrees.

You have control over the setpoint, you cannot control the latter....

Hope this helps.

@Hans

thanks for your reply! Did you connect de ELGA using the Opentherm Gateway using the Interface Firmware?

If I understand you correctly, you only need to send the Opentherm messages 16 (Room Setpoint) and 24 (Room Temperature) to control the ELGA.

To make the gap between hot and cold I need to set the circulation pump as low as possible... I had some issues with the ELGA that it didn't start when there wasn't enough flow (at least that is what I think as it did start when I increased the power setting of the circulation pump).

thanks

Eric

No, I use the normal 4.0 firmware. Interface firmware is something for the (remote) future. I only send the setpoint override command, the thermostat itself sends the room temperature.

/not OpenTherm related:
If you want to learn more about the Elga and its peculiarities, may I suggest the tweakers forum?
(http://gathering.tweakers.net/forum/lis ... es/1560938)

About the pump. Set it as high as reasonably acceptable. Higher speed means higher COP.