Evohome + Opentherm + Viessmann Vitodens 100

[Stulin]

I'm looking at introducing a Opentherm gateway between the evohome and my Vitodens 100 to allow me to control the flow temperature manually or even possibly automatically from climate/ seasonal data.

Has anyone had experience with this DIY gateway project? http://otgw.tclcode.com

Having done a small amount of research it would seem possible to relay the R8810A & boiler opentherm commands through the gateway but crucially also allowing the addition of the temp flow ID data set on the gateway to be passed to the boiler.

Even though the project is somewhat DIY you can purchase pre-assembled boards for those less handy with a soldering iron (like me!) https://www.nodo-shop.nl/en/48-opentherm-gateway

Thoughts on the above would be welcomed.

Stu

[baloghta]

I have lyrics t6R, with the same problem with opentherm. Viessmann does not help, says this is honeywell's fault. But I can set parameters in the thermostat. Software update resolves the problem so that I can set maximum heating water. Now I can set hot water temp. Why does not honeywell do it?

[Richard]

I have lyrics t6R, with the same problem with opentherm. Viessmann does not help, says this is honeywell's fault. But I can set parameters in the thermostat. Software update resolves the problem so that I can set maximum heating water. Now I can set hot water temp. Why does not honeywell do it?

The problem doesn't reside with Honeywell, the problem is with Viessmann for not allowing a maximum central heating temperature setpoint at the boiler.

Honeywell fully complies with the requirements of the OpenTherm spec and this does not state that OpenTherm controls MUST control the maximum central heating temperature setpoint. A decent OpenTherm boiler following the OpenTherm specification, will allow this to be set manually at the boiler (as Intergas boilers do).

This is very much a Viessmann problem and if Honeywell choose to control DHW temp setpoint and CH temp max then this is in addition to what is 'REQUIRED'...

[baloghta]

I have lyrics t6R, with the same problem with opentherm. Viessmann does not help, says this is honeywell's fault. But I can set parameters in the thermostat. Software update resolves the problem so that I can set maximum heating water. Now I can set hot water temp. Why does not honeywell do it?

The problem doesn't reside with Honeywell, the problem is with Viessmann for not allowing a maximum central heating temperature setpoint at the boiler.

Honeywell fully complies with the requirements of the OpenTherm spec and this does not state that OpenTherm controls MUST control the maximum central heating temperature setpoint. A decent OpenTherm boiler following the OpenTherm specification, will allow this to be set manually at the boiler (as Intergas boilers do).

This is very much a Viessmann problem and if Honeywell choose to control DHW temp setpoint and CH temp max then this is in addition to what is 'REQUIRED'...

Thanks for the answer. What do you recommend? Do I use with opentherm or on / off relay?

[baloghta]

The documentation said:


https://www.honeywelluk.com/Documents/F ... 0sheet.pdf

Max Supply Water Setpoint 90 30 tot 90 °C (appliance depending) - future

"future"?

[Richard]

Thanks for the answer. What do you recommend? Do I use with opentherm or on / off relay?

I would recommend you get a decent OpenTherm boiler...

The documentation said:

https://www.honeywelluk.com/Documents/F ... 0sheet.pdf

Max Supply Water Setpoint 90 30 tot 90 °C (appliance depending) - future

"future"?

If you read the section its says 'read only' as in this is data you can obtain from the boiler over OpenTherm in a 'read only' format. AFAIK, there are no plans currently by Honeywell to have the thermostat set max flow temp.

[baloghta]

Thanks for the answer. What do you recommend? Do I use with opentherm or on / off relay?

I would recommend you get a decent OpenTherm boiler...

The documentation said:

https://www.honeywelluk.com/Documents/F ... 0sheet.pdf

Max Supply Water Setpoint 90 30 tot 90 °C (appliance depending) - future

"future"?

If you read the section its says 'read only' as in this is data you can obtain from the boiler over OpenTherm in a 'read only' format. AFAIK, there are no plans currently by Honeywell to have the thermostat set max flow temp.

I have a viessmann boiler, I can not change it, I do not want it.

Opentherm or not?

[Richard]

OpenTherm is great, but maybe W/C hybrid if max flow temp can't be adjusted?

[baloghta]

OpenTherm is great, but maybe W/C hybrid if max flow temp can't be adjusted?

What is W/C hybrid?

[Richard]

OpenTherm is great, but maybe W/C hybrid if max flow temp can't be adjusted?

What is W/C hybrid?

Exactly...