“Ventless” Fireplace Products: Efficient Heat at What Price?
With today’s modern construction of nearly airtight homes, indoor air quality is an even larger issue than in past times. “Vent-Free” or “Ventless” gas logs, stoves and fireplaces are a very controversial subject. They aren’t 100% ventLESS or ventFREE, they basically vent into your home. Debates among scientists, the gas industry, local code officials and manufacturers are taking place all over North America. Vent-Free heaters are not new. They have been in use in Europe before WWII. Vent-Free appliances have become very popular with consumers as efficiencies run to 99%; they do not require vent pipe and involved installation; they can be installed almost anywhere (providing square footage requirements are met); and they are fairly inexpensive. The reason there are requirements for adequate square footage is to assure there is enough space to dilute the combustion by-products. All ventless appliances built after 1980 are built with an ODS (oxygen depletion sensor). This device assures that the ventless appliance will shut down if the oxygen level in the room falls to 18% or below (21% is normal). Before purchasing a vent-free appliance, there are important considerations. There are odors associated with these units. When there are other odors present in the home, such as fresh paint, cigarette smoke, household cleaners, plug-in air fresheners, oil lamps, finger nail polish, new carpet, etc., these odors and other airborne contaminants are drawn into the burner and altered by the combustion process. This creates some unusual new odors and can cause some discoloration to walls and ceiling. Another important consideration is that since water vapor is a product of combustion, this humidity is forced into the home. A vent-free heater will exhaust a significant amount of water vapor into the home. This effect can cause excessive moisture on the windows, even contributing to rotting the windowsills over time. Common results of excess moisture are wallpaper peeling, mildew, mold and furniture damage.
If you already own a vent-free appliance you should clean and inspect it regularly. Each home has its own environmental characteristics, affecting the way your appliance performs. A dirty appliance or one that is out of adjustment can cause sooting on walls, carpet and furniture. Ventless log sets are designed for the flame to come out of the burner without coming into contact with the logs. Should the logs be accidentally moved or the flame pattern be altered by a draft (such as a ceiling fan), the flame could contact the logs causing flame impingement. This situation can result in release of carbon monoxide gases. It is also another cause for major sooting problems.
Ventless products are rated 99% heat efficient. This means that 99% of the combusted fuel energy is released indoors. However, some of that energy remains trapped in water vapor until it condenses on cold surfaces such as exterior walls and windows. Manufacturer owner manuals often contain a statement requiring a nearby window be opened when the appliance is lit.
The following is an excerpt from an article in November 1998 Consumer Reports
Magazine outlining their independent testing of vent-free gas fireplaces. “…our tests confirm that these heaters contribute significantly to indoor air pollution. If you are planning to buy a gas fireplace, a vented model should be your first choice. That is especially wise if any household member has asthma or another respiratory ailment that may be exacerbated by particulate matter, or if your home is very airtight—and so will disperse the fireplace’s emissions less readily…”
A direct vent gas appliance is a better alternative. Products are available as complete fireplace units, freestanding stoves and inserts designed to fit in your existing firebox. These appliances use minimal venting, a small vent going out the side of the wall, much like a dryer vent. Direct vent heaters take their combustion air from the outside, not robbing the home of oxygen, then vent the exhaust back outside. This isolates the living area of the home from combustion wastes, maintaining your indoor air quality. Most direct vent units are in the range of 80% efficiency, many offering a lifetime warranty and realistic flame appearance. They serve as powerful heaters and/or an alternative heat source, adding value to your home.
When you really think about it, what is a fireplace? It is a contained fire within your home to provide warmth and beauty. It is often the focal point of a family gathering place. Your home is usually your biggest investment and a safe and healthy environment for you and your family. Perhaps this is not the best product to save an additional few dollars.