Yes, a direct vent gas fireplace can be put anywhere in the house if the vent lengths and turns meets the rules of the manufacturer which are shown in the form of charts & diagrams in the installation instructions. It can vent horizontally to an outside wall or vertically through the roof within those rules. The roof termination would be an exposed metal pipe. Fresh/combustion air is drawn into the outer wall of the vent and the center pipe acts as the exhaust for combustion byproducts. A B-vent gas fireplace can only vent to the roof and draws combustion air from the room (or through a separate outside air duct). It can have a glass face or bi-fold doors. Either unit might have heat recirculating louvers or not. If you find the roof termination unattractive you can add a fake masonry or wood surround. Roof leaks shouldn't be an issue if the roofer knows how to flash a roof penetration. Be sure to use Ice & Water Shield self-adhering flexible flashing in addition to the factory metal flashing. Click on one of the direct vent gas fireplace installation manuals and see if the vent tables will work for your installation. It's a lot of design work if the vent travels horizontally and vertically. Here is a link that might be useful: installation manuals

Thanks for your input, Renovator8. That fireplace has been through a few transitions. It was first an Isokern masonry like fireplace but to save some money we changed it to a b-vent on the plans. Once we placed the house on the lot, it became apparent that the b-vent pipe would be viewable from the street, and would have to be fairly high due to the slope of the roof. The initial hope was to hide the b/vent pipe from view behind the upstairs Isokern chimney, but the house is oriented in a way that it is viewable on approach, even though not seen in the front or back yard. We then changed to an direct vent. The whole reason for the direct vent was to not vent to the roof, so I would like to avoid that. We have a couple of options with the Montebello like running them behind a bookshelf in the dead space and then over a boxed bay bumpout, but the pipe is so big it may make it not feasible. I don't think we have enough rise available to run it over the master bedroom tray ceiling above, unfortunately, because that will vent out the side of a house above the a/c in a very inconspicuous place.

Unfortunately we had to make the through the roof decision yesterday because today the cedar shake roof went on and there is no turning back now. We are going out the side of the house, for better or for worse. Today I took my husband to an appliance store in hopes that we would be looking at washers and dryers. What else did the store sell? Vent a Hood. The salesman got hold of my DH and you know the ending. Yes, my DH loves Vent a Hood. So right now I am showing him all the information on this site re how noisy it is, etc. but I am losing the case. Help. Any opinions out there would be greatly appreciated.

It shouldn't be extended outside since it may freeze and cause the unit to stop working. It may be relocated to another area from inside and re-terminated outside. Venting codes need to be followed with certain dimensions adhere to from openings, doors and windows. It can never be vented into the chimney however, many times as long as no other appliances or fireplaces use the chimney; it can be used as a chaseway for the piping out the top.