Home heating with radiators

Wall heaters are sized according to wattage.  Therefore, you want the heat output of the heater to match the size of the room it will be used.  This is important for efficient operation.  When deciding on the proper size of wall heater, you must consider the size of the room and the amount of heat loss that the room has in order to maintain a comfortable temperature.

To determine the room size, measure the length and width of the room, and then multiply these two numbers to give you the square footage of the room.  For example, if your room measures 12 feet by 14 feet, it would be 168 square feet.

To determine heat loss, consider when the home was built.  Newer homes usually have significant amounts of insulation, and double pain windows making the giving the room very little heat loss.  However, homes built before or during the mid-1960s, may have very little to no insulation and single pain windows will have a greater amount of heat loss.

With this information, you can make an educated choice on the size of wall heater you will require to efficiently heat your room.  The rule of thumb is that it takes 10 watts of heat per square foot for rooms that are above average for energy efficiency; 12 watts per square foot for rooms that average for energy efficiency; and 15 watts per square foot for rooms that are below average for energy efficiency, such as rooms in older, colder homes.

Therefore, for a 168-square-foot room with above average energy efficiency, you would want a heater that is approximately 1,680 watts (168 x 10), which would be either 1,750 or 2,000 watts.

It is important to realize that these examples are for a room with standard 8-foot ceilings.  Therefore, for other size rooms, you will need to make the following adjustments in your calculations.
• For every 2 feet of ceiling height over 8 feet, you will need to increase the heater’s wattage by 25%.
• For rooms with a large amount windows or glass doors, you will need to increase the wattage between 25% and 50%, depending on the size of the room.
• If your room will require more than 2,000 watts, then divide the needed wattage in half for two heaters.
• Bathrooms should use heaters with a minimum of 1,000 watts.  This is due to the demand for faster heating and the amount of humidity.

These are only general guidelines and for more in depth information concerning your needs, you should speak to your heating retailer, electric company, or a certified electrician.  You should also keep in mind that installing a wall heater will require the installation of a separate electrical circuit, as well as an electrical permit.  To ensure that your wall heater is properly installed, always consult with a licensed.