A fireplace "insert" is intended to fit into a pre-existing masonry fireplace. I assume you mean a metal factory built "zero clearance" wood burning fireplace for new construction The wood burning fireplace "duct" you mention is a chimney whether it is masonry or metal. You can add gas to the firebox or put a gas log kit in it but the chimney must still be designed for a wood burning fireplace and sized for the fire box opening (unless you want to pay for it to be tested by UL). You need to either try harder to get the chimney offsets to work or use a metal factory built gas fireplace already tested by UL with a B-vent through the roof. Factory built gas fireplaces are made in two types: Direct vent and B-vent. The Direct Vent unit has a double-walled metal vent pipe that can terminate on an outside wall or through the roof. It is a closed system so the fireplace gets combustion air from outside through the outer wall of the vent and the firebox has a fixed glass enclosures. The B-vent unit has a single-walled vent that can only terminate through the roof. The fireplace takes combustion air from the room so it can be open to the room. Many of the units have folding glass doors. Carefully read the instruction for installing the vent. Consider an optional outside air supply duct to the firebox.

Here is another previous post on the subject: posted by: renron on 12.19.2006 at 07:28 pm in Fireplaces Forum First, DON'T install a ventless fireplace!!! Even though the MFG.s will tell you the exhaust fumes are OK, do you really want to breathe them? Many people end up with Major Headaches and chronic breathing issues. Does it sound like a good idea to breathe burnt exhaust gasses? B type flue(vent) pipes are dual thickness pipes. A pipe inside another pipe, suitable for use at 1" or more to flammable materials. Outer casing pipe is sealed and will not conduct air. D (Direct Vent) type flue(vent) pipes are also dual layers but they are capable of exhausting burnt gas through the inner pipe and importing exterior(outside) combustion air for burning. Think of a straw inside a larger straw. Inside straw blowing, outside straw sucking outside air for combustion. A fan is usually used to help exhaust the burnt gasses. Details below: B-Vent (Natural Vent) gas fireplaces are designed primarily for decorative use. Generally they produce a larger and more realistic yellow flame. B-vent fireplaces are sometimes available without a glass window, so many homeowners are attracted to this design because of the open, realistic flame effect; some models do have a glass window so the existence of a window on a fireplace does not define its product classification. Natural vent gas fireplaces use room air for combustion and vent fumes through a vent or chimney that must terminate vertically above the roof line. The key to determining whether a B-vent fireplace will meet your heating needs is to check the manufacturer's listed efficiency rating (gas consumed x efficiency = heat output). While efficient, heater-rated B-vent fireplaces do exist, many lower quality "builder grade" fireplaces have no efficiency rating and, therefore, will not supply substantial heat. In fact, this category of fireplace will often use the greatest amount of gas at the lowest range of efficiencies. If you live in a warmer climate where you want the aesthetics of a fire without much heat, this may be the appliance for you. Likewise, bedrooms and smaller rooms may be a good candidate for a b-vent fireplace, but please check building codes to see if this class of fireplace is approved in your locality or for installation in the room where you'd like to use it. Local/national codes in some areas prohibit the use of b-vent rated appliances, especially in colder climates. Be aware that very "air tight" houses can cause performance problems with b-vent rated appliances, so please consult an experienced fireplace installer who can advise you on the proper installation and use you are considering. Direct Vent Fireplaces offer the most features with respect to gas consumption, efficiency ratings and venting options. A direct vent fireplace will always have a glass window because these fireplaces are sealed systems using a double walled venting system. Combustion air enters the appliance via one section of pipe while fumes and moisture are vented through the other pipe. Most often, a double wall "pipe within a pipe" system is used. Subject to each model's requirements for distance and offsets, direct vent fireplace venting may be terminated either horizontally or vertically. Efficiency rating will average 65% to 84%, similar to ratings on gas furnaces. Keep in mind that these appliances must "waste" some of the heat produced to create a draft of rising warm air to evacuate the fumes produced without aid of a forced air exhaust system. Think of direct vent fireplaces as a decorative furnace: the beauty of a realistic flame with high efficiency. This appliance is great for primary or supplental heating and for emergency backup heating as most work without aid of electricity. Because this is a sealed system that uses outside air for combustion, direct vent fireplaces are usually the favored choice among those in the fireplace industry because of their greater efficiency and exceptionally reliable performance. Hope this info helps, I am a General Contractor. Renron

I've got to say that I hate our gas fireplace and would trade it for yours any day. Ours is just flicker of a yellow/blue series of flames that don't crackle or pop. I guess to each his or her own. That aside, if I was doing it again and wanted the heat advantage only, then I'd make sure to get one of the gas fired ones that have the blower and is somewhat sealed behind the glass. Otherwise, you still have the sucking of the cold air, but with none of the advantages of a real wood fireplace. I don't know the technicalities, but I'd shop around for several installers and see if you (they) can change the orientation and get at least 3 bids. Personally (although I'm not an expert) I don't see why you can't alter the flue/vent, but the cost would be more for sure. It's probably just up to the cost of redoing things and how much you are willing to pay. The stone veneer is a great idea and easy to do yourself. Also, consider stone tile. This post was edited by audiomixer on Thu, Feb 7, 13 at 23:20

That is a really nice set Rebbecamom. I think your concern was wixe because, from the photos, it looks like the cabinets projecting at the side of the fireplace may cross the zone where you shouldn't have combustibles with a wood fire. At least for our wood burning fireplace, the installation instructions say there should be no combustibles in front of a line that goes out from the side of the firebox at 45 degrees for 24" on each side of the fireplace up to some height above the fireplace. I don't know how universal that requirement is, so perhaps your set up would have been okay with your fireplace. We put in a wood burning fireplace for the family room that is sealed so there is no issue with embers or sparks. It heats the family room really well and provides the look of real flames, but one can't hear the crackling of the fire. Also, we don't feel comfortable running it when our little grandchildren are visiting because the glass gets really hot - if we were going to run it with small children around, we would probably want to put a protective fence of some sort around it which would not help ambiance. It uses external air intake which can be adjusted to control how hot the fire burns and to damp down the rate of burn. It is nice to not have to worry about leaving the fire going when we go to bed. For the living room fireplace, we are considering putting in a gas log set - we have never used that fireplace and have no need of running it for heat, but it would be nice to turn it on occasionally for looks when using the room. We don't need two heating fireplaces and I don't want to deal with wood in the living room.