Opentherm behavior... how your boiler run?
I have a Viessmann 100 B1KC 35kw and is connected with the wireless receiver on +/- opentherm. Boiler is modulating and is ok,but at low heat request(1 wave) the boiler will not fire till at least 2-nd wave displayed and this time between 1-st and 2-nd level of heat request will ONLY run the pump and can't understand why and what is the point if not fire and just running the water for long,mostly around 1-2 hours before reaching the 2-nd wave when the boiler fire. Let me explain ,, in facto ": heat set at 21°C and room temp at 21.5°C,all fine. The confusion start at 21.3°C when the first wave appears and the receiver display heat request(connected via opentherm with the boiler bus),in that moment the pump start to run,the boiler fire for 15sec and stop and again pump run till the temp not goes down to 20.8°C and second wave showed when finally boiler fire and run for 10-15min,modulating power,all good. When boiler stop the pump continuing to run for 1 hour or more,this is confusing for me.
How your boiler do? Pump is running long period of time without boiler to fire? Is this ok or normal? Hope to get some answers. Thank you!
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I have a similar model (35kw B1KF), Tado confirmed it supported Opentherm with the Tado system, and I configured Tado to be set to D01, and it seems to be working for me.
If your pump is running when Tado isnt calling for heat, are you sure no other device is calling for heat anywhere - I think its shows this on the care and protect button. Or maybe that boiler is set somehow to keep running.
Either way, I guess if Tado is not calling for heat and the boiler is heating, then its a boiler question for Viessmann?
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@Floob Wireless receiver has the wave light on for calling heat from boiler .On the app if set temp is 21 and actual temp is 20.7 it shows only 1 wave( low req) and therefore boiler fire for 10-15 sec and stop and only the pump us running...at the moment,pump run for about 1hr:45 and till temp drop to 20.5 will do the same....annoying! Is not using gas but the electricity is waisted by running the boiler pump for nothing.
I cant understand this behaviour,if i do connection on/off relay the boiler(or Tado) is not running pump for so long but the advantage of opentherm is lost.
In fact,in 24 hour time the boiler pump is on for about 14-15 hours.This is not normal for me and i repeat,it happend only with opentherm. Is Tado opentherm still learning? I use it only for a week or so.
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Is see the same behavior. Installed Tado 2 days ago. When heat is requested. The the boiler starts pumping water at 22 degrees. This is useless. Then later it goes to 33. Which is better. And Then to 42. Which is fine. But running at 22 for an hour? It should start at 33. But I gues Tado is stil learning? Did it get better with you? @BOG730
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@Jelledrm it has been a year since,Tado is still working in the same way,first wave heat req very rare to fire the boiler and thus the only pump run sometimes for an hour or less,depending on heat loss. I guess your house is well insulated and heat loss is slow. So,dont expect Tado to work better in this situation. But,i can see an improvement(maibe learning but dont think is learning really😜) in Opentherm behavior cause it run better,low flow temp,mostly at 40C or less when outside 0-5C temp.,modulating the output of the boiler and try not to overshoot the inside temperature. To recap your issue with the Viessmann pump...use the smart schedule,set a time of max 2 hr(mine is 75min) to call for heat and if your desired temp is 21C let say,after this schedule time set a temp lower then 21,maibe 19.7 or 19.9 or whatever but not 20.8 cause the pump will run till the inside temp will drop to min 0.5 C to desired temp and only after boiler will fire. Hope this clarify for you. Cheers0
