In theory, if you read, understood and followed ALL the numerous warnings that go with unvented equipment, it could be operated with reasonable safety. But I've never encountered a single person who did that.

Vented is safe, but NOT energy efficient because most of the heat goes up the chimney. So if you want serious heat, safely and efficiently generated, go with direct vent. It's more costly, but in the end a better choice.

"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"

Good luck.
-Gary G

We had a standard masonry fireplace but we hated the mess and smell and lack of heat from wood. We did have the chimney inspected when we moved in and it was obvious the prior owner used it.

Note our main source of heat is a heat pump for our two story 2000 sq ft home.

We looked at vented vs ventless vs an insert. The cost was about $500 for a ventfree logset or vented logset and about $2800 for an insert. (add $550 for a used tank or rent yours) If you can afford it the insert is the way to go. They throw off heat and supposedly have no smell at all, no fumes etc. It was out of our price range though.

My dad has a vented logeset. It throws off a GREAT looking fire but in most homes you will realize no heat. His room however is small and enclosed and he does get some heat from it; enough to make it warm and even warm his bedroom upstairs. Probably not economical though. In most cases you are not going to get any heat; especially if you have an open floor plan as our house does. Still if you just want the ambience the vented is fine. Realize though your chimney must have the damper locked open all year allowing your heat and ac to go up the and out...unless you have a REALLY good quality door set...which if you were going to invest in you likely would just get the insert!

The vent free set does not have nearly as nice a fire. Still it does throw off heat...a lot of heat. If you have an open floor plan you likely won't have any mositure issues. If anything you may need to turn your down humidifier a bit. You can control the amount of heat by adjusting the flame and even by opening the damper.

We really just wanted the ambiece but opted for the vent free set figuring the heat could be nice if it worked out and if not we'd just open the damper.

Well, the thing does throw heat but it smells. They say ANYTHING in your house can cause the smell as the flames burn whatever is in the air...bath spray, cooking odors, fresh paint or carpet, galde plug-ins etc. Well we eliminated all that and still have the smell. I think the gunk in the fire place from the prior owner's wood is what is combusting and throwing off the smell.

Anyway, we find we have to open our damper a little less than half before to eliminate the odor problem. It does throw some heat into the room especially if on for a few hours. If I could close the damper all the way it would heat our first floor (1000 sq ft)easily.

I did run the thing with windows and doors open and vent closed once this fall to try to burn the smell out of the fireplace. I think I was partially successfull as I can close the damper more now. Maybe I will try again.

I can just say that if you can afford the insert go for it. Of course if you do so, realize that if your thermostat is on the same floor as the the insert it likely will not kick on much and your second floor will get cold...even with your the heat pump's fan running. That has happened to us even with our log set only partially closed. Of course if you have stats on each floor you should be in good shape.

Good luck and be sure to invest in a carbon monoxide detector for each floor.

If you're considering a vent-free, do the research and make sure you're putting it in a room that has lots of air access. Get permits and have pros install it. Install the CO detector nearby. Keep a window cracked. This is my second gas fireplace--as a rule, flip off all the gas lines off-season.

If I have problems with the vent free, I promise to log back on and eat crow.