Factory-built fireplace

[Brian A. MacNeish]

Originally Posted by jwilliams4

Vent-less gas logs (often referred to as "Vent-Free" gas logs) have specially designed burners that burn the gas cleanly and produce almost no exhaust—somewhat like the way a gas range in a kitchen works. Since there is little or no exhaust, they can be burned with the damper closed.

The beauty of this type of system is that 99.9% of the heat produced by the gas logs goes into the room, so they produce substantially more heat than their vented counter-parts. However, there are many negative features commonly associated with vent-less logs that one must be aware of before deciding to purchase them:


Positive Features of Vent-less Gas Logs:
1. Much better heat output than vented gas logs
2. Less pollution
3. Slightly less gas consumption

Negative Features of Vent-less Gas Logs:
1. Since the byproduct of burning gas cleanly is water, vent-less logs will introduce excess moisture into your home which can result in mold or mildew.
2. Vent-less logs should not be burned for extended periods of time with windows closed, otherwise they will deplete the oxygen in your home.
3. If vent-less logs are burned for more than an hour or so, a window must be open a crack to allow air into your home to replace the oxygen burned by the vent-less logs. This will introduce cold air into the room and offset some of the heating benefits that vent-less logs claim to have.
4. Vent-less logs produce an odor that some equate to the smell of burning kerosene. If one has a keen sense of smell, the odor may be greatly dissatisfactory with vent-less logs. (On the other hand, some people like the smell because it reminds them of their childhood days at Grandma's house.)
This odor is the oxides of sulfur/nitrogen and other constituents.......not really healthy stuff for any one and especially those with borchial problems!!!

http://www.atsdr.cdc.gov/tfacts175.html

http://www.battelle.org/environment/.../article7.html

http://stripe.colorado.edu/~shellym/...Dutton2001.pdf

5. Vent-less logs are not legal in California as well as some cities and municipalities in other states (check with your local building department). However, one can still purchase vent-less logs in California—they will have to be used with the damper open (which really defeats the purpose).
6. Vent-less logs are required to have an ODS (oxygen depletion system) as well as a CO detector, which might tell you that there are some risks involved in operating them in the event of system failure.
7. The flame pattern with vent-less logs pales in comparison to vented logs. Because the gas must burn cleanly, the flame height is very low and most of it is blue.
8. Also, one may find that the flame does not “dance around” like a real wood fire and very little of the flame actually touches the logs. The reason for this is that when the flame touches the logs, it gets cooled off and does not burn cleanly and starts to produce soot and exhaust gases.

Huge amounts of water vapor are produced by Vent free gas logs. It is estimated that 1.5 gallons of water is produced for every 100,000 BTUs of gas burned. As these systems burn around 30,000 BTUs per hour, it requires only 3 ½ hours to produce such an amount of water. In the case of Vent free gas logs, these vapors can condense on windows and other cold surfaces present in the room which can create severe moisture problems. Hence, these products come with directions for leaving a window slightly open during use.

http://www.carbonmonoxidekills.com/

How can they claim that they burn cleaner and with less pollution????