I found that the cost of the power vent and direct vent were both high enough that it made sense to go to a high efficiency tankless or hte AO Smith Vertex units. You can sometimes also get a rebate from teh utility for them as well. Most of hte HE units vent with regular PVC like your power vent. When I looked at direct vent units, they were pretty pricey. The blower goes away, but the flue pipe get larger and more complicated and is stainless steel I believe and requires specific vent pipe.