Image Alt TextImage Alt Text
Image Alt Text
Image Alt Text

Hidden Health Effects of Vent-free Gas Appliances


Hidden Health Effects of Vent-free Gas Appliances

Super-clean-burning and boasting a toasty 99.9% percent efficiency, choosing between a vent-free gas log and a vented gas log appears to be a “no-brainer” considering today’s high gas prices. Since there is no vent, every drop of heat remains inside the home… none is yanked up a chimney only to heat the great outdoors.

   At first glance, vent-free gas fireplaces seem to be all positives with no negatives. Lower purchase and installation cost (no holes to cut or pipes to buy) certainly is a real plus.  A ventless fireplace can be set in places that no vented fireplace has gone before, such as on the first floor, directly beneath an upstairs bathtub.  Since absolutely no heat is dumped outside, operating costs are smallest 

   So, what’s the catch? Since there is no vent, just where does the exhaust go?  Why are these fireplaces rated at 99.9% efficiency, rather than 100%? What is in the one tenth of one percent?  

    Well… almost all the fumes are consumed by the fire, which actually is extremely clean-burning. But, is “almost” good enough when it comes to breathing clean air in your own home?  Unfortunately, there are still measureable traces of chemical residues remaining in this exhaust, including carbon monoxide, which of course, is an odorless, colorless and tasteless poison.

   Although there certainly are lots of happy vent-free fireplaces users, if you are have been working hard to alter your lifestyle by changing eating habits to avoid excess fat, sugar and overly processed foods, exercising, quitting smoking, etc., you may want to think twice before buying a gas appliance which constantly oozes enough pollutants into the air you breathe in your home to compare with the atmosphere on the corner of a very busy thoroughfare in a large metropolis.    

    Traces of various other chemicals besides the carbon monoxide do create a slight odor.  Some people with a poor sense of smell may only notice this odor for the first few minutes after the gas logs are turned on, while others with a more sensitive noise may compare the odor to that of a mild kerosene heater. Sensitive people, those with allergies, asthma, or other respiratory problems may find the exhaust irritating, to the point where even a relatively short period of use can routinely trigger headaches,  congestion and  asthma attacks.    

    There is even a warning in fine print on the metal data plates wired to each unit concerning those with heart or lung disease, anemia, and even pregnant women, who “are more likely to be affected by carbon monoxide than others.”  

    A separate issue is the excessive moisture given off by vent-free systems which can encourage mold and mildew, and can create a yellowish film given time in a tight home, if the vent-free logs are run excessively as a main heat source. All manufacturers recommend using vent-free only as supplemental heat and not as 24/7 primary heat. When using vent-free strictly for emergency heat, many of these negative “side-effects” are minimized to the point of a non-issue. 

    For those wanting to research this subject further, check out the following websites. The first offers a forum for homeowners who have questions about vent-free or who have already “been there, done that.”

Another well known website site of interest is:  Type in “gas fireplaces” in their search box, and click on the first article listed, entitled “Burning Controversy.”

   So, what’s the alternative? You may have heard that you’ll lose almost all the heat produced by a vented gas logset, not to mention that the fully open damper will pull out a tremendous amount of heat you just paid for from your central system. Unfortunately this is true.       

    However, there is a type of high-efficiency vented gas appliance called “direct-vent,” which is an airtight unit, sealed with a single sheet of glass, with hidden gaskets and clamps.  This seal prevents any fumes from escaping into the room, and also prevents the fireplace from sucking in expensive already heated air just to feed the fire. 

     There are two versions:  The first, a “fireplace” version,  simply frames into a wall (for new construction or remodeling) which can then be decorated to look like a conventional fireplace. Fresh air gets pulled in from outside, in between a double vent pipe, while the exhaust leaves through the inner pipe.  The “insert” version is short and is designed to install inside an existing woodburning fireplace. This direct-vent “insert” has two separate flexible vent pipes running up the chimney --- one carries out the exhaust, the other brings in the fresh outside air.  Blowers and heat exchangers surrounding the firebox blow out intense heat. The best heating   direct-vents   use a ceramic glass (rather than tempered glass) to better pull heat out into the room.  Most direct-vents units average around 80% efficiency, but some are considerably higher.

   Is there a “catch” on these direct-vents?   Yes, direct-vent fireplaces and inserts cost considerably more than vent-free counterparts. But… if the cheapest route was the only thing that ever mattered to most people, we’d still be seeing lots of Yugo’s driving by.

    For a comparison sheet listing pros and cons of both vented and vented-free, go to Click on the “Hearth  Articles” menu to find the list comparing vented with ventless.   

    To get more information on the pros and cons of vented and ventless, visit Custom Fireplaces showroom, where you can see dozens of working displays of both vented and ventless, as gas log sets, as inserts and as built-in fireplaces.  They can be reached at 931-526-8181 or 800-264-8181 or emailed at Store  hours are Monday through Saturday, 9:00 – 5:00 (and by appointment beyond regular hours). Custom Fireplaces is located at 1611 E. Spring St. (Hwy 70 N) in Cookeville, in between Hwy 111 and I-40, exit 290.

Total: 0 Comment(s)