propane water heater venting

Currently putting on low-profile barrel tile roof on "weathered in" addition, so considering options for venting the future water heater. I'm leaning towards a wall vent vs. a roof vent to avoid another roof penetration and potential flashing problems with the tile. Intuitively I think I would prefer to have a non-powered unit. Had the propane co. tech (who does their plumbing work) out, but he wasn't real familiar with through the wall venting. Have googled a bit & looked at the non-powered unit on the Bradford-White site. Plan to talk to my local plumbing supply and try to find a local familiar with wall vented units, but sure would appreciate some opinions before I get to the part of the roof where I would have to put the vent if that option turns out to be better for some reason.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.