Subscribe to Fine Homebuilding magazine now and save up to 52%
One thing that also must be considered about this calculator is that it shows payback in terms of months and years, but because there is no explanation I assume that these are only months when the furnace is running. So an 8 month payback means actually more like two Winters in some places. The 26 year payback could mean more like 52 years!
© 2016 The Taunton Press, Inc. All rights reserved.
Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.