I can't answer many of your questions but yes a b vent needs a chimney, but it can be a metal chimney (looks sort of like an attic vent). It would be something you would want on the back side of your house, but not particularly obtrusive. B vents vent vertically and can have a bend in them but I am not sure how far they can run horizontally, if you need them to do so to reach the back of your house.

A direct vent would vent out to the side of the house so it would not matter if you have a second story. I don't know how long the "run" to the outside can be, but I am sure someone else will chime in.

The big difference I have seen is that B vents function like a normal fireplace and don't have to have glass in front of them. Direct vents all have glass (although you can get clearview ones which don't have louvers on the front just glass inside the firebox).

The other thing to look at is whether they are zero clearance. These help them look more realistic too as they are sitting where a traditional fireplace would, rather than being raised up.

Thanks, athensmomof3. It sounds like a B vent could run straight up and out the roof of the second floor--but it would be best on the back side of the house.

I'd like to have glass in front of the fireplace to keep CO and any smoke particles (?) out of the house (two family members have asthma). Not the gorgeous look of a masonry wood burning fireplace, but we'd enjoy it.

Zero clearance is a very good point. I'll look for that.

Anyone else have an idea of cost?

Thanks!
Liz

If you do opt for direct vent you can also get custom doors from http://www.stollfireplaceinc.com/direct_vent_fireplace_screens.asp. Lots of options in lots of finishes, in case the fireplace you end up with does not come with the doors you like (options are pretty limited)

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

Zero clearance refers to a factory manufactured metal fire place that can be as close as 1 inch to combustible materials.

macv, thank you for the detailed information and the link to direct vent installation manuals. I'll look through them tonight. The idea of a fake masonry or wood surround on the roof sounds more promising than an exposed metal pipe. I've saved your information about Ice & Water Shield too. Thanks also for the clarification on the term "zero clearance". It is wonderful to get this kind of information so quickly. All the best, Liz

Here is a fake stone chimney hiding a large chimney from a zero clearance wood burning fireplace.

Here are two gas fireplace direct vent terminations.

macv--what a difference! I know the direct vent box on the side of the house is not attractive, but I'd say the metal pipes on the roof are worse. The fake chimney is an improvement. I'm not a fan of fake, but sometimes it is better than the alternative. Many thanks. Liz

Everyone has a different opinion about such things. I would tolerate almost anything on a roof in order to avoid disturbing the face of a building especially near the ground where you can see it up close. The metal terminations are not intended to be painted (usually galvanized or stainless steel) but it can be done. Black hides them against the roof and grey hides them against the sky.

The chimney hidden in the fake stone enclosure looked great on an ocean front house so we left that one exposed.

The slope of the roof makes a big difference in how much of a chimney you can see when standing close to your house.