Hi, Guys: Anyone out there have experience installing the Buderus GB142 wall hung units? We are about to convert our 50-yr.old cast iron oil-fired Sunnyday boiler to natural gas. We are leaning towards the Buderus high-efficiency. My question has to do with correctly sizing the boiler for both heat(I have cast iron rads) and domestic hot water. We will be going with an indirect hot water tank, a 40-gallon one has been advised. We are a family of two with occasional houseguests. We have two bathrooms.
I have gotten conflicting sizing of boilers from different contractors. My heat loss for my 1700 square foot 1960 single-level ranch is ABOUT 50K BTU. One contractor wants to install the GB142 24 size and one wants to install the 30. The contractor pushing for the larger boiler says to be safe with the indirect, you need to go bigger. I'm even wondering if we could get away with the Buderus 32 gallon HW tank. Any help appreciated! I don't want an oversized boiler OR indirect tank if I don't need one. Thanks for being out there, guys. We all appreciate it!