A lot of the wall heaters here in Long Beach, ca. are very old and need major work. If the heater looks like it has all original parts, and hasn't been serviced in years, we normally recommend a complete rebuild, which consists of replacing the safety valve, pilot generator, gas shut off valve, the gas line, and adding a wall thermostat to make the unit more efficient. We also completely clean and vacuum the entire heater.
Floor heaters are basically the same thing as a wall heater, except that it sits in the actual floor of the home. It still needs to be vented properly and needs to be cleaned regularly as a lot of debri can easily fall through the grill of the heater. Many floor heaters need a considerable amount of work as they are subject to a lot of moisture that comes from under the home.
Forced air heating is a little more sophisticated than wall heaters, and some even use a computer to control heating.
The general principal is the same as all heating, but forced air adds a blower motor that blows heat through ducting in the home.
Venting is also crucial with these, and it is recommended to have the ducts cleaned at least once a year, as a lot of dust and allergens can build up in the ducts.
Whatever your heatings needs are, Don's Appliances can help keep you warm!