7. Not Recommended
In addition to knowing what to look for in an energy-efficient gas fireplace, it is important to know what is not recommended. In the case of gas logs, ceramic logs with gas burners are placed directly into an existing wood fireplace to give the effect of a burning fire. These gas logs provide no real heat to the house and are essentially a waste of energy and money, as well as a potential source of pollutants, although they can provide an attractive fire.
Gas logs can also cause venting system problems, particularly in colder regions. This is primarily because wood fireplace chimneys are not designed to handle the low-temperature, low-flow, high-moisture flue gases generated by a gas fire. If a wood fireplace chimney is not relined to accommodate these gases, the chances of flue gas condensation and chimney deterioration are high. As well, if the fireplace is on an outside wall, there is a risk that the gas burners will not generate enough heat to create a good draft. Under these conditions, the house can become a better chimney than the chimney itself (see "The house as a chimney"), disrupting the flame and drawing carbon monoxide and other combustion products back into the living area.
8. What to Avoid
A type of gas fireplace to avoid in Canadian housing-the vent-free gas fireplace-is available in the United States. As the name implies, these units do not vent to the outdoors; all the combustion gases (including carbon monoxide, carbon dioxide, nitrogen oxides and large amounts of water vapour) are released directly into the house. These fireplaces can cause serious indoor air quality and moisture problems, particularly in airtight Canadian homes. They are not approved for use in Canada.