I ended up removing an 8 year old Mini Therm 50 boiler from an apt where it was heating and firing a 36 gal indirect. I'm thinking that in another 3 family house that currently has a regular 75 gal WH, I could replace it when it goes by buying an indirect for not much more than a replacement 75, power it with the boiler, and save gas with a more efficient system. Is this boiler simply too underpowered for the idea? I looked at 75 gal WH BTU's and they're all over the place. The house has 3 2-bedrooms apartments and a washer in the basement. Any thoughts?