The purpose for the power vent is so you can use PVC for a flue, as far as I know, and these HWH are much more expensive than a simple convection type water heater. If I had a good chimney nearby, I would use the simple type. Why complicate something that has worked for years through natural convection? If you need a power vent, you need it. If you don't you don't. What is your situation?