That is a good unit actually. Buderus throws more cast iron that all other boiler companies combined. I had a Buderus in my last home with the side arm tank beside the boiler. If I was to have your system I would have rigged up lifting points to be able to simply throw a couple come alongs on it and lift the boiler off enough to slide the tank into place. If they are planning on dropping the boiler to the floor, I would suggest that you ask them to build the lifting points in permanently.

When my Buderus indirect went to the dump I switched to a tankless. I saved space, money and had a lot of hot water. If you have limited space, you could have them pull the indirect tank out, lower the boiler to the floor, repipe the drops and set a tankless above the boiler. I would strongly suggest that as an option.

Thank you for the feedback.

I burn oil and I don't think the tankeess one is an option

It is even worse because it is only the transfer coil which has a hole in it but with this model you can't just change the i you have to change the whole tank. Even wore they don't have a stainless steel replacement for it. It is a lost cause.

I am getting quotes to go with the Superstore stainless steel one on the side.

I would look at a Phase III as well. You could change your oil burner to a Riello gas burner and go tankless. The trick to doing well with propane is owning your own tank. Big tank that is. That way you aren't getting a fill every 2, 3 or 4 weeks in the middle of the heating season.