Is there anyone who has one of these as their heating unit for their home? We moved into a house last year that has Viessman boiler that is now 24 yrs old. It works fine all we wanted was someone to do a go over yearly maintenace check on it. We called 2 different heating businesses that apparently 'specialists' in installing/maintaining specifically Viessmann units. Both service call visits from 2 different businesses, neither of these guys had a clue about how our 24 yr old boiler "works". We were charged by the hour to have the guy stand there dumbfounded while he charged us $$$-by-the-hour-time, to read OUR Viessmann manual....!! We are in a dilema because there is just no one that knows anything about maintaining/trouble-shooting this particular brand of boiler that is MADE IN GERMANY.. Even though ours still works fine, all they want to do is sell us a brand new modern version of Viessmann boiler. Would like to hear from anyone who has experience with owning an older model Viessmann German made boiler..