I had a vitodens (200, I think), in my last house that the previous owner installed. It was incredibly cheap to run and gave me no problems in the 8.5 years I lived there. Wasn't easy to fine someone to even do pm's on it though.Viessmann ...best on the market.Has the correct turndown ratio
You may be limited on what is accessible.I’ll check out the Viessman. Yes I’m planning the install myself