Vented Gas Logs Require a Fully Functional Wood Burning Fireplace and must be burned with the damper open,
Ventless (or Vent Free) Gas Logs can be installed in either a wood burning
fireplace, or a ventless fireplace that is rated for aftermarket ventless logs and are burned with the damper closed.
Ventless gas logs will produce more heat, while vented gas logs will look much
more realistic. Read the Pros and Cons of each below:
Vented Gas Logs:
"Fully Vented" gas logs must be
burned in a fireplace that is capable of burning real wood and must be burned
with the damper open. The reason for this is that they do not burn the gas
cleanly and create exhaust that is very similar to burning a real wood fire.
This exhaust needs to be able to go up the chimney. The real beauty of vented
gas logs is that they produce substantially more yellow flame than ventless logs
which makes them look far more realistic. The downside is that most of the heat
goes right up the chimney.
However, In most cases, you can offset this heat loss by
slightly closing the damper...but you must be careful that the exhaust from your
logs is not coming into the room because, just like burning real wood, it
contains Carbon Monoxide. A good way to test this is to turn on your gas logs
with the damper slightly closed. Hold a lighter or candle in front of the
fireplace opening near the top. If the flame from the lighter (candle) is being
drawn in toward the fireplace, then you are OK. If the flame is standing still
or pushed out toward the room, then your fireplace is not drafting enough and
you must open the damper more.
Positive Features of Vented Gas Logs:
Extremely realistic flame pattern that looks like a wood fire.
Flame is much taller than ventless logs
Flame dances and wraps around logs like real wood.
Does not require a CO2 detector
Since the damper is open, most of the smell will go up the chimney
Ventless 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 ventless logs that you must be aware of before you
decide to purchase them:
The main byproducts of burning gas cleanly are Carbon Dioxide and Water Vapor. Because of this,
ventless gas logs will introduce excess moisture into your home which can result in mold or mildew.
You must be careful not to burn your ventless logs for
extended periods of time with windows closed, otherwise they can potentially deplete
the oxygen in your home.
If you burn your ventless logs for more than an hour or
so, you must crack open a window to allow air into your home to replace the
oxygen burned by the ventless logs. This will introduce cold air into the
room and offset some of the heating benefits that ventless logs claim to
Ventless logs produce an odor that many people equate to
the smell of burning kerosene. So if you have a sensitive nose, you may not
be able to handle the smell and will be greatly dissatisfied with ventless
logs. On the other hand, we've heard some people who like the smell because
it reminds them of their childhood days at Grandma's house.
(Read Why Ventless Gas Logs Smell)
Ventless logs can cause eye irritation and coughing spells to those who are sensitive.
Ventless logs are not legal in California as well as some
cities and municipalities. However, you can still purchase ventless logs
from us if you live in California...you will just have to burn them with the
damper open (which really defeats the purpose).
Ventless logs are required to have an ODS (oxygen
depletion system) as well as a CO2 detector...which might tell you that
there are some risks involved in operating them if these systems fail.
The flame pattern with ventless logs is not nearly as realistic in comparison
to vented logs. Because the gas must burn cleanly, the flame height is very
low, it is more blue than yellow and appears to be more nerveous and less lofty.
Also, you will 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
Installing vent-free gas logs is not a DIY job. Installation must be performed
by a professional who can do the proper tests on your gas pressure and make sure
that the installation meets building codes and follows the specifications required.
Clearances to combustables is different than that of wood buring fires or vented gas logs.
If there is a mantel above the fireplace, you may need to install a hood to divert heat away from it.
You should check the
Installation Manual for the Ventless Logs for clearance requirements before you
There are also BTU limitations based on the cubic feet of air available to your room. The maximum BTUs allowed is
calculated using this formula: Room Width x Room Length x Ceiling Height x 20.
Ventless gas logs may not be legal in a bedroom or confined space (differs with local building codes).
Other restrictions apply with each of the various burner systems available, so again, you should read the
installation manual pertaining to the ventless logs you are considering "Before You Purchase".
Bottom Line: We highly
recommend that you purchase vented gas logs. You will be much happier with flame that they produce
and less likely to experience discomfort from odors or irritation.
We only recommend ventless logs when maximizing the heat output outweighs all of the other negative aspects.