What would you do if the directions of your vented gas log fireplace said: “Step 4: Turn on gas and light log set with a flaming $10 bill”. No matter what you tried, you couldn’t get the gas log to light unless you burned a $10 bill and put it to the logs to light it. I think you would be tempted to write the manufacturer about this issue, or talk to the store you bought it from, or maybe just not use it!
The inefficiency of a vented gas log fireplace
In a way, this is what it is like to use a vented gas log fireplace. You get little to no usable heat from the device, you consume fuel in it, its use/or non-use sucks heat from your home, but it sure makes a nice flickery flame. Is it worth it?
There are some key elements that are dead wrong with vented gas log kits. The primary issue is the damper use with these kits. Most state building codes say if a vented gas log is installed in a fireplace the metal damper has to be locked open or removed. The reason for this particular code is so that people don’t turn on their vented gas log and forget to open the damper and therefore asphyxiate the inhabitants of the home. The reality of this code is the homeowner has to live with a sizable hole in their homes energy envelope that is releasing energy 24/7.
Vented gas logs do not produce usable heat
The vented gas logs combustion process does little to produce usable heat to the living area. Much like a wood burning fireplace the vented gas log wastes heat in many ways. The combustion process grabs already heated air from your home and burns the oxygen and combustible gasses in it. The heat that is created in this combustion quickly rises and grabs more heated inside air and tosses it up the chimney. You can restrict the amount of inside air that the fireplace has access to by installing glass doors, but this will also severely limit the amount of radiant heat that fireplace can cast forward into your living space. This radiant heat is the heat you feel on your skin in front of the fireplace, and is the only usable heat that the fireplace will produce since the combustion heat is pouring out the top of the chimney. In the meantime the home is drawing in cold outside air from other places (i.e. windows, light sockets, doors, etc) to replace the air that is escaping the home through the chimney. This is referred to as the “stack effect”.
How much money and heat is lost?
Most vented gas log operate at a consumption of .5 to 1 Therm per hour. In January of 2008 one Therm of Natural Gas cost me $1.57. So if you burn your vented gas log for 3 hours you wasted $4.71 worth of fossil fuels, and have no heat to show for it. With that same amount of natural gas you could have heated a 1200 sq ft home with a 95% efficient power vent furnace all day long.
Vented gas logs are good for ambiance
The flickery yellow flame that is produced by a vented gas log is a very realistic looking flame, but it is a low temperature flame and therefore tends to burn “dirty” and outputs soot and other pollutants. If you have a vented gas log fireplace or are considering having your wood fireplace fitted for one. Consider first the cost and environmental ramifications of using it.