AES Hearth & Patio sells, services, and installs Gas fireplaces by Heat N Glo, Quadra-Fire, Ambiance and Lopi Fireplaces in Carlisle, Chambersburg, Mechanicsburg, Shippensburg, Camp Hill, and Harrisburg, PA.
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Direct Vent Gas Fireplaces and Inserts – The Healthy Hearth Choice
What is a “Healthy Hearth” Choice?
A direct vent gas fireplace or insert is the best hearth choice when it come to protecting the air inside your home that your family and friends will breathe. A direct vent design hearth product is engineered to include a sealed glass front that keeps gases such as carbon monoxide, nitrous oxide and excess moisture from entering your home. The glass front of a direct vent model gives you a full, clear view of a beautiful fire. This design uses air from outside your home to fuel the gas fire rather that pulling air from inside.
Are direct vent gas fireplaces the kind that don’t have a chimney?
Not exactly. Direct vent gas fireplaces need to be vented outside, however this vent, or “chimney” can be run horizontally through an outside wall. In this sense, it doesn’t require a traditional chimney that extends vertically above your roof line. You should be careful however not to confuse direct vent with unvented gas hearth products.
What is an unvented hearth product?
Unvented, or more correctly, “room vented” products are designed to operate with all the gases and other by-products of the burning process coming into the room. They use an ODS or Oxygen Depletion Sensor which may act as a safety shutoff should the unit not operate properly. In addition, several manufacturers of unvented hearth products also include a carbon monoxide detector as part of the system.
Are unvented models safe?
Yes, when properly sized, installed and operated, they are listed to be safe by ANSI standard Z21.11.2 However, many building scientists and indoor air quality experts have voiced concerns that proper sizing and operation of ventless models is not occurring in all circumstances.
What could happen if an unvented model is not properly sized to the room?
The biggest concern is excess moisture in the home. A principle by product of burning gas is water vapor. An unvented appliance operating at 25,000 BTU/hr will put approximately one quart of water per hour into the room! In new homes which are tightly insulated by today’s energy codes, this excess moisture can become “trapped” in the home, condensing on cool surfaces such as window glass and frames. This in turn, can lead to the development of mold and mildew which have a negative impact on the air you breathe inside your home. Room size to meet AGA sizing guidelines (with an 8’ ceiling) required to accommodate an unvented fireplace.
What else should I know about the differences between Direct Vent and Unvented Hearth products?
For starters, you should check with your local building code to confirm if unvented products are allowed to be installed. For instance, there are several states that ban their use entirely.
Secondly, consider the “comfort control” you have with direct vent models. Many offer options that allow you to put excess heat into other rooms, or outside the home completely if you choose. (A nice feature when you’re entertaining a room full of guests.) Since all the heat from an unvented type product comes into the room, it can make a room uncomfortably hot in a hurry!
Lastly, while unvented products are technically “safe” when sized, installed and operated properly, there are several reputable sources and industry experts who do not believe they are “healthy” in certain conditions.
“We truly believe that direct vent fireplaces and inserts represent the “Healthy Hearth” choice for you, your family, your friends; for anyone who gathers at your hearth. Enjoy…Relax…Breathe easy!”
But don’t just take our word for it. Consider these statements from industry experts when making your decision:
“An unvented gas fireplace thats safely sized needn’t pose any acute health hazard. But our tests confirm that these heaters contribute significantly to indoor air pollution. If you’re planning to buy a gas fireplace, a vented model should be your first choice.” Consumer’s Report Magazine November, 1998
“The date in the AGAR (American Gas Association Research) report on unvented appliances suggests that tighter houses may not be suitable for the installation of unvented products. This is especially true for colder regions of the country, or when cold snap periods are occurring in milder zones.” Paul Stegmeir, Hearth Industry Expert on Indoor Air Quality
“Direct vent, sealed combustion models are the only type of gas fireplace we allow in our Health House project.” Dianne Walsh-Astry, Director National Health House American Lung Association