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Vented Vs. Vent Free (Vent Less)

This is General Information only. A full publication on the subject will appear on this site in the future.

When shopping for a gas stove, fireplace or gas logs you may be asked to choose whether you want vented or Un-vented.

We at FlameWorks strongly believe in choice and there is no other dealer in the US (that we are aware of) that offers as many hearth choices focused on efficiency. Un-vented products are nearly 100 percent (in the real world the efficiency is lower, more later) efficient, BUT FlameWorks does not offer* Un-vented hearth products…. Why? Read on.

FlameWorks only* handles vented hearth products, but dealers who sell Un-vented products have reasons for offering the product line. The decision comes down to several factors including usage, health concerns, looks vs. efficiency, local codes and placement of the unit.

With vented fires, you'll almost always enjoy a larger more realistic-looking flame that operate with an open chimney flue, or damper with the case of gas logs. These logs, which simulate a wood-burning fire, are more decorative than they are efficient as a heat source because much of the generated heat goes up the chimney. Direct-Vent hearth appliances operate differently and although some heat goes out the vent it is balanced with air coming in from the outside for combustion and results in efficiencies ranging from respectable to exceptional.

Un-vented units operate with the chimney flue closed or no flue or venting at all. They will not give you that roaring fire effect -the flame is not as realistic or as high as you'll find with most vented units. But, Un-vented logs are an efficient heat source because nearly 100% of the heat generated stays in your home. You'll often see Un-vented logs referred to as "vent-free heaters" because that is essentially what they are. Un-vented heaters add moisture to the air, so it's important to install them in a room with proper ventilation to avoid formation of mildew. Also, the by-products of combustion are released into the living space as well.

Before installing any gas Un-vented system, check your local and state codes. In some localities, Un-vented heaters are not permitted. Un-Vented heaters (any form: logs, fireplaces, stoves or utility units) are nor permitted in bedrooms, sitting rooms, bathrooms or recreational vehicles, and must be installed in an area where curtains, furniture, clothing or other flammable objects are clear from the perimeter of the heater a specific distance, often 36”. Un-Vented heater installation also is not recommended in high traffic, windy or drafty areas, due to possibility of flame impingement and sooting. Most importantly, Un-vented units are no a good choice for individuals who have allergies, asthma, emphysema or chemical sensitivities. Check with your doctor before installing a Un-Vented fireplace, stove or log set.