[Daox]

Power vent hot water heaters are a lot more expensive, but they're also quite a bit more efficient. Sadly, the rheem isn't all that much more efficient. Most natural gas units with the exhaust up the middle are ~55% efficient. This one is 67% (still 20% less gas used than a 55%). They get up in the high 90s though if you're willing to pay up front for it.

When you think of how much your hot water use accounts for in your house, its usually worth paying extra for it. With my old (now replaced) 55% efficient gas water heater, I used about $230 worth in hot water a year ($0.95/therm). Going to a 67% efficient water heater would save me $40/year, or $400 in 10 years (assuming gas prices don't go up, haha). Going to Rheems 82% efficient water heater would save me $75 per month, or $750 in 10 years. The efficiency adds up fast! I've been told most tank water heaters tend to last ~10-15 years depending on your water, and your maintenance habits.