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I am planning to replace the 65 year old Columbia boiler, with tankless coil, in my 1200 square foot house. I have had two contractors look at the layout of my system, and one recommended a Biasi B-10/4 , and one recommended a B-10/5. To add to the confusion, I have been offered a slightly used Buderus G215/3 in exchange for removing it from it's present location, due to the owner switching to gas.
The house is a single zone, with about 13 feet of baseboard in one room, and 19 feet of Beacon Morris convectors throughout the rest of the rooms. I would like to incorporate a Triangle Tube Smart 40 indirect water heater in the new installation.
The contractors I spoke to recommended the Biasi primarily due to it performing well with a poor draft situation- the existing boiler exhausts via a 12 foot long horizontal run to a 8" sq tile lined chimney. I have since decided to install a new triple wall chimney adjacent to the new boiler, whatever it may be, to assure the best possible draft.
They both recommended a boiler with low mass since there are no big radiatiors- just the baseboard and convectors. The water capacity of the Buderus seems quite large at 12.9 gallons and I am concerned that that might be a major source of inefficiency in my case. I'm sure it was an asset in the original location in an older home with big radiators.
Is the Buderus an acceptable boiler for my new application, since it is available for the removal, or is it too oversized for my application to result in any substantial economy over my old boiler.?The claim made for the Biasi is the boiler can "go cold" except when heat is required due to it's low water volume. I am making the assumption that this would not be the case with the high water volume in the Buderus. I value any comments and advice you wish to offer!