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Viessman vitodens b2ha-19 control issue? Setting

Have an Vitodens 200 B2HA-19 with Vitotrol 200 room tempature sensor. The set up is for a room that is heated on it own. The boiler runs radiant floor for a sun room and IDHW only. House has gas forced air not on boiler , so I have it set to use a reduced room tempature at night. Here is a new problem, at night used to work fine before it got to 16 outside. At night the floor circuit pump is set to run if it gets so cold 37 out keeps floor curcit pump running but not the burner. The other night when it was in reduced room temp the floor was warm ie burner was on with the boiler. I check the control to see if it was making hot water for the indirect, it wasn't. The outside tempature was 16. Normally the heating curcit pump will run if below 37, but never the burner. I check to make sure party button wasn't pressed. I pressed the piggy bank, it said invalid operation, which has always meant it is already in stand by mode. I checked the boiler by pressing information then heating curcit and the operating status was in standby mode. That should have meant that it will heat if room gets to 37 red room temp stpt. That night I changed the mode of heat and hot water to off then back on both. It did stop the burner, but I think the outside temp also went to 17 the burner then turned off. Tonight it's 16 and burner is on boiler running in standby mode which is set for 37 even thought the room tempature is 67. The burner is on and boiler temp is 140 and has been on for the last hour. Only way is to turn off burner is to change the room tempature down then the burner will go off, but not a solution because then when it is scheduled to turn on in morning it will stay at that temp. Any ideas? What coding is turning on burner at the lower outdoor temp. Standby by mode should mean reduced room tempature stpt of 37. When it gets to 16 the burner is on ignoring the standby mode temp of 37. Thanks in advance for any ideas. Sorry for the long post. I do understand that most don't use setbacks for floor heat but is shut and night and set to come on early in am and warm floors feel great for the kids.


  • heathead
    heathead Member Posts: 229
    I think I have the fix. In the code settings F8:5 is set to what the germans call tempature limit for terminating reduced mode. I beleive it was set from factorty at 23 degrees. I think that when the outside tempature hits 23 degrees it takes it out of reduced mode (night set back ) and sets it to run in normal mode ie heating like its running during the day. Does anyone have cheat sheet that does a better job explaining all the coding options. Thanks to all. Hope this helps someone else.