controld..
Thanks for your question. When we had gas logs installed when our
house was built, I had no clue regarding vented vs non-vented and what
the differences or advantages were. Now, I do. :)
One major thing to consider when comparing vented and vent free is the
amount of use the gas heater will have. By that I mean, will the
heater be running unattened, such as overnight? Will it be a primary
source for heat in the space or is it a secondary heating source?
Other considerations are your locality's building codes. Some states
and cities do not allow vent-free gas heaters be installed in homes.
Some other things to keep in mind from The Vent-Free Alliance,
http://www.ventfreealliance.org/ :
an extremely tight home — if your home shows symptoms of an
inadequately ventilated home (moisture on inside of windows, mildew,
and shower or bath humidity lingers), additional ventilation may be
required prior to adding vent-free gas appliances. Also, if you have
an extremely tight new home, talk with your builder or contractor to
make sure your home is properly ventilated.
homes at high altitude (i.e. homes at 4,500 feet above sea level or
higher) — homes in higher altitudes may experience nuisance pilot
outage and flame shutdown due to lower atmospheric pressure
If after you have determined that vent-free heaters are allowed and
your home is adequately ventilated, you need to determine the size of
the heater to use. This is done by determining what U.S. Department of
Energy Heating Region you live in. You can look at this map,
http://www.cozyheaters.com/images/usa2.jpg , to determine which
heating region you are in. From there, you can use the chart found at
http://www.ventfreealliance.org/codes.htm to determine the correct
size of vent-free heater you will need to maintain comfort.
In regards to the energy costs and outputs of vented versus vent-free,
vent free units run at 99% fuel efficiency. This is because by
advanced air/gas mixing chambers, burner designs, and other features
all developed to produce the cleanest, most complete possible burn.
Also, since there is no chimney or vent to allow heat to escape, the
efficieny is increased. Some people are afraid that vent-free
products will take "all the oxygen" from a room. This is simply not
true because all vent-free appliances have what are called Oxygen
Depletion Sensors. The ODS shuts of gas feeding the heater when the
oxygen level in a room falls below a certain percentage. Another
concern is moisture that is created by vent-free heaters. Typically,
vent-free appliances do not add any more moisture to a room during a
normal day than a shower. A good average to use would be for every
1,000 btus, 1 ounce of moisture will be created per hour of use.
Air-quality of the space has been addressed in a study in 1996 by the
American Gas Association's Research Division. This study showed the
levels various by-products combustion and the emissions amount from
vent-free appliances vs indoor air quality guidelines and
recommendations. Looking at the results at
http://www.gamanet.org/consumer/ventfree/pr/popsci.htm you will see
that emissions from a vent-free appliance were well below the IAQ
guidelines.
Thanks again for your very interesting question and I hope the
information I have provided meets your needs. If not, or if you need
additional clarification, please let me know prior to rating my
answer.
Stay warm!
Regards,
-THV
Search Strategy:
vented vs vent free
Gas Appliance Manufacturer Association
References:
Vent Free Gas Products Alliance
http://www.gamanet.org/consumer/ventfree/
Gas Appliance Manufacturer Association Consumer Information
http://www.gamanet.org/consumer/consumer.htm
Illinois Propane Gas Association
http://www.ilpga.org/cons_vfree.asp
Vent-Free
http://www.heatershop.com/vent_free_safety.html
Space Heating Questions
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