Viessmann 222 Heats to room temperature when cold outside, no matter what room temperature set at

mcbiech

Hello, We have a Viessmann 222 Central Heating System. When I set the room temp to be 18C, all is ok until the weather cools down. Then it brings the room up to 22C no matter what I do. I can set the room temp to 15, no matter, the radiators stay hot until it's 22C. I have looked through the settings to see if there's a weather setting I can adjust, but can't find it. Any feedback?

Paul Pollets

Turn the heating curve down, make sure the night time setback is lower than the setpoint, if you're using it. Read the manual for adjusting the heating curve. I presume you've installed the outdoor sensor?

mcbiech

Thank you .... Yes, the outside sensor is installed and it's just below freezing outside. The heating curve was at 1.4 ....... I am going to bring it down to 1.1 and see how we do. Thanks very much!

Paul Pollets

every .1 turndown usually results in a 3 degree difference in output

mcbiech

Thanks, I am getting results!