Wall Heaters 101
With winter around the corner, now is a good time to start thinking about how you'll warm up those cold rooms. If you're looking for a permanent heating solution, an electric heater might be just be what you need.
There are several types of electric heaters available, but the two most common styles are wall heaters and baseboard heaters.
Understanding How it Works
An electric wall-mounted can heater has three parts. First, a metal can is installed in the wall and is usually attached to the side of a stud. The heating unit is located inside the can, which includes the heating elements and a small fan. To finish things off, a decorative safety cover is installed over the can and the heating unit. The cover prevents direct contact with the heating elements and includes louvers to help direct the heated air.
An electric baseboard heater attaches directly to the face of the wall. It mounts right where the wall and floor meet, hence its name. Baseboard heaters have an electric element inside, and the element is covered by a series of metal fins. Baseboard heaters are typically fully assembled, and require only screwing to the wall.
Wall Heaters vs. Baseboard Heaters
Both types of heaters work on electrical resistance. Electricity flows through the heating elements, which are designed to resist the electricity. This creates friction, which in turn produces heat. The primary difference between the two is in how that heat is delivered to the room.
The can heater has a small fan in it. The fan blows across the heated elements, forcing the heat through the grill and into the room. With a baseboard heater, heat from the elements warms up all the thin metal fins on the cover. The fins then radiate that heat into the room, without the use of a fan.
With both styles of heaters, the demand for heat is controlled by a thermostat. The thermostat may be mounted on the heater itself, which is less expensive but, since it's affected by the warmth of the heater, is also less accurate. The other method is to mount the thermostat on a wall, which increases the accuracy but requires additional wiring. In larger rooms, one thermostat may be used to control more than one wall heater.
Sizing Your Wall Heater
Electric heaters are sized according to their electrical usage, measured in watts. When choosing one, you want to match the heat output of the heater to the type of room the heater will be used in. To properly size a wall heater for efficient operation, you need to consider both the size of the room and the amount of heat loss that you'll have to compensate for in order to keep the room comfortably warm.
First, determine the square footage of the room by measuring the length and width of the room, and multiply the two numbers. A typical rule of thumb is to allow 10 watts of heat per square foot if the room is well insulated and has generally good energy efficiency.
For rooms with less insulation or more moderate energy efficiency, figure 12 watts per square foot. In an older home with no insulation, poor windows and overall low energy efficiency, you may want to increase the allowance to 15 watts per square foot.
These are just some general guidelines -- for more specific information on sizing a wall heater to meet your specific needs, talk to your heating retailer, your electric utility company or your electrician. Also, remember that adding a wall heater requires a separate electrical circuit, and in most jurisdictions it also requires an electrical permit. Always consult with a licensed electrician if you have any questions about safe and proper installation.