Gas wall heaters work by convection, which means that they heat the air in front of people and objects, giving the room a toasty glow. There are two types of gas wall heaters. Some gas wall heaters have a pipe to the outside that allows them to pull air into the unit which in turn allows the gas to burn. This same pipe expels any possibly harmful fumes back outside as well. There are also ventless gas wall heaters, which work a little differently and actually draw the air from the room in order to heat the room.
Ventless gas wall heaters that were installed before 1980 should be replaced because they do not have the oxygen depletion sensor that newer models have. While most gas wall heaters only last about 20 years and the chances of someone coming into contact with a working one that was installed before that are slim, some older homes still have them.
The oxygen depletion sensor in newer models will shut off the gas automatically if the oxygen levels in the room drop down to 18 percent. This is very rare though.
Gas wall heaters have some definite advantages. First, they give off a very even heat with no drafts, whereas an electric wall heater may work harder to blow enough warm air into the room to heat it. Another advantage is that gas wall heaters will continue to work even if the power is out. Finally, they are self-contained, which means that they need no boiler.
Gas wall heaters also some have a few disadvantages. The main disadvantage is that they are not so good for heating your entire home. They will only heat the room in which the wall heater is mounted. Another disadvantage is that when you use gas to heat there is a byproduct from the fossil fuels. Finally, if you try to install your gas wall heater yourself, there is the possibility of gas leaks.