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Lighting Seattle since 1905 Jorge Carrasco, Superintendent
Conservation: Your dollars

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Conservation: Home Heating

We call a heating system zonal if its design allows it to heat different areas of a home independently of each other. Thus a colonial era home that had a Franklin stove in the living room and a cook stove in the kitchen could be said to have a zonal heating system. Today, zonal heating systems generally run on electricity.

A zonal heating system contains several heat-producing devices in contrast with a central system which has only one. In a zonal system each heater can usually be controlled independently of the others. The majority of Seattle residents have electric powered zonal heating systems. Most apartment dwellers and many single-family homes have electric baseboard heaters or similar devices. Recently we have seen more installations of electric heaters recessed in walls. These units have small fans to blow the heated air into the room. Both baseboard and wall heaters have thermostats that control them. These controls are generally mounted either on the wall of each room or on the heater itself.

Electric Baseboard Heaters
Electric baseboard heaters have long been popular among builders because they cost less and are easier to install than furnaces. In apartment buildings this system allows the building owner to place the responsibility for controlling and paying for heat on the tenant. In the days of cheap electricity, users seldom suffered from the shortcomings of baseboard heaters. These shortcomings include poor distribution of the heat produced and large fluctuations in room temperature. However, as the price for electricity has risen, many people have looked for ways to get better value out of their heaters.

Baseboard heaters are very simple devices. They contain a metal core that has a high electrical resistance. When current passes through the core the energy gets changed from electrical to heat. The core is surrounded with thin metal fins that conduct the heat produced to the air around the heater. The heated air moves into the room through convection. Convection is the movement of warm or cool air in a space.

Baseboards have customarily been located under windows in order to improve the distribution of the heat into the room. The theory behind this design assumes that there will be a downward flow of cold air coming off the window and an upward flow of warm air coming off the heater. The two streams will meet, and their combined flow will get pushed out into the room. Unfortunately, the real world defeats this theory in many cases. Widespread use of efficient windows has dramatically reduced the amount of cold air coming off windows. Moreover, in many rooms the wall area under a window is the perfect spot against which to put a sofa or other piece of furniture thus blocking the flow of warm air.

One common misconception about baseboard heaters is that they are inefficient. In fact, they are 100% efficient in producing heat from electricity. Unfortunately, they can be ineffective at delivering the heat to where you need it. You can easily calculate how much energy your baseboard heater uses if you know how long you normally run it. All you need is a tape measure. Measure the length of the baseboard heater. Each foot of length draws 250 watts of power. Thus a four-foot baseboard draws 1000 watts or 1 kilowatt of power. For every hour you run it, it consumes 1 kilowatt-hour (kWh) of electrical energy and costs about nine cents.

Heaters recessed in a wall
Recessed wall heaters convert electricity into heat much like baseboard heaters. They differ from baseboard heaters because they also contain a small fan that blows the heat out into the room. This design greatly improves the distribution of heat, but it also makes for a noisy heating system. These heaters are usually located in interior walls so as to minimize the heat loss to the outside. Because the heat they produce has a greater intensity than baseboard heater, you cannot place plants or most plastic items in front of the heater.

To determine how much power a recessed wall heater demand, you will have to find the specification plate on the unit. You can then use the specification data and our calculator to figure out its energy use.

For more information from Seattle City Light on home heating, please
e-mail or call 206.684.3800.
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