With winter on its way, you may be thinking about some different options for warming up those cold rooms. If you don’t like the idea of moving portable heaters around and you’re looking for something permanent, an electric heater might be just the solution you need.

There are several types of electric heaters available, but the two most common styles are probably the wall-mounted can style, and the baseboard style.

An electric wall-mounted can heater has three basic components. A metal can is installed in the wall first, usually attached to the side of a stud. Inside the can is the heating unit, 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.

Both types of heaters work on electrical resistance. Electricity flows through the heating elements, which are designed to resist the electricity. That 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 the 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. …CONTINUED

First, determine the square footage of the room. Simply measure the length and width of the room, and multiply the two numbers. For example, if your room is 12-by-14, it would be 168 square feet.

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.

So, for a 168 square foot room with good energy efficiency, you would want a heater that’s rated for at least 1,680 watts (168 square feet times 10 watts per square foot). Chances are you won’t find a heater with exactly that wattage, so always choose the next highest one — in this case, it would probably be either 1,750 or 2,000 watts.

Here are a few additional tips when sizing electric room heaters:

  • Increase the wattage of the heater by 25 percent for every 2 feet of ceiling height over 8 feet;
  • If your room has a large amount of glass in it, increase the wattage by 25 to 50 percent to compensate for heat loss through the glass;
  • If your room requires more than 2,000 watts, divide the required wattage in half and utilize two heaters. For example, a room needing 3,000 watts should have two 1,500-watt heaters rather than one of 3,000 watts;
  • Because of the demand for faster heating and the amount of humidity present, bathrooms typically should have a minimum of 1,000 watts of heat.

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.

Remodeling and repair questions? E-mail Paul at paulbianchina@inman.com.


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