About Space Heaters
Space heaters are made in a variety of different ways. There are two types of heat that a space heater might generate.
This sort of heat is heat that is transfered from one medium to another using the adjacent materials, specificaly molecules. The direction of heat flow is from higher temperature to lower temperature for example from a heating element to the air and then from the air to the human body.
This sort of heat is more electromagnetic than anything else. A heated item will emit radiative heat and you might feel this heat even though the air around you is cold. Take the sun for example. There is no air in space to heat so the rays from the sun travel through space and heat the earth.
Space heaters use either of these types of heating, sometimes in combination, to warm you. Some portable space heaters use conductive heat. This includes oil-filled space heaters and most heater fans. An infrared space heater, for example, will use mostly radiative heat to heat you.
Things to Consider When Buying a Space Heater
There are several things to think about when buying a space heater:
Size of Area
If you are trying to heat a large area, using a single space heater probably won't work well. Even a very hot heater will only raise the temperature of a large room slightly. You might consider using multiple space heaters to do the job but then the consideration becomes electricity usage. If you have too many heaters running at the same time you are likely to blow a fuse. Space heaters work great to heat smaller rooms. So if you find yourself spending lots of time in a smaller room or office, then think about using a space heater instead of modifying your home HVAC system.
Use of Room
Some space heaters make noise from the fans used to emit the heat. Therefore you mgiht not want to use a heater fan in a bedroom and instead opt for using a ceramic or oil-filled heater. Heater fans might work a bit better for a larger space where the air circulation will assist in warming the space.
Space heaters can get very hot. Modern space heaters have built in mechanisms to shut off when tipped over, however this mechanism does not prevent children from touching space heaters or from clothing to mistakenly be placed on top of the heater. You also want to be careful of curtains and rugs, in addition to furniture. You should always place a space heater in an open area. Wall mounted space heaters can help to insure that your space heater is never obstructed.
Most importantly, you should consider that physically you can only be in one room at a time so if you wanted to you could opt for space heaters over traditional heat if you are able to turn on/off heaters as you enter or leave a room.
Timers and Thermostats
If you are concerned about forgetting to turn off your heater or worried that a room might get too hot when you leave it, consdier buying a heater that has a built-in timer or thermostat.
A built in timer usually acts like the "Sleep" mode on an alarm clock. You can set it to go off after a certain number of minutes.
A thermostat will actually monitor the temperature of the room and when the room meets or exceeds the temperature setting you specify then the heater will shut off automatically.