Depends on the peak load...a typical WH is normally in the 45-60K BTU, so the boiler is in the ballpark, but more complex. It might be more efficient. A commercial tank that size has a much larger boiler and could provide more first hour hot water, though. I think it may be undersized for that application. Depends somewhwat on the size of the indirect and how hot you keep it. It would likely require a tempering valve, which makes it look like a bigger tank. It may be normal for all occupants to take their showers in the morning near the same time getting ready for work...that can take a substantial system. If recovery isn't a big problem, then a big tank that can be heated with the small boiler would work.