BTU Sizing

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
I have a lead on a used (three season old) Buderus G115/5 for a great price.
My house is roughly 2,000 square feet and very well insulated with new windows.
When I run various online BTU calculators I am coming up with less BTUS than the 115/5. However, I want to add a zone out my 400 square foot shop. This boiler is rated at 120K BTUS.

Would the 115/5 still be too big? Just about right? What is the danger in being potentially on the wrong side of either the 115/4 being too small, or the 115/5 too big?

Thanks.