All About Baseboard Heaters

Electric baseboard heaters are best used to supplement the main HVAC system in your home, to compensate in areas where the main heating doesn't reach well, or to selectively heat one room or area. While they're usually not efficient enough to serve as the main heat source, the exception might be homes in mild climates where a forced-air system and its ductwork is too excessive and unnecessary. Employed strategically, the use of baseboard heaters can actually lower energy costs.

Baseboard heaters are a type of ductless heating system that doesn't have to be connected to your ductwork. There are two basic types of electric baseboard heaters: electric convection and electric hydronic, and within those broad categories are numerous variants. All of the baseboard heaters are long and narrow, encased in metal, and are designed to hug the wall at the baseboard. A few models of baseboard heaters come equipped with a fan to assist in air circulation, but most types rely on convection for their circulation system.

Convection is based on the principle that cold air falls and hot air rises. The heaters receive colder air at the bottom, pass it through the heating coils and release it out the front, where it rises to fill the room. That's why baseboard heaters are usually placed against an exterior wall and below a window or bank of windows. The cooler air descending from the surface of the glass panes energizes the convection effect and promotes circulation of the heated air.

Both electric convection heaters and electric hydronic heaters are available as portable units that are corded and plugged into a standard 120-volt, 20-amp outlet, and as hard-wired units that require either 120 or 240 volts. For optimum efficiency, the 240-volt hard-wired baseboard heaters are the best choice.

Baseboard heaters are available in a range of lengths and wattages. For best results, the heater you choose should be adequate to the dimensions of the room it will heat. To determine the appropriate baseboard heater size, multiply the length times the width of your room to determine the square footage.

Each square foot of your room requires approximately ten watts of heater capacity, so multiply the number of square feet by ten to determine the watt output of the heater your room needs. Most electric baseboard heaters specify their wattage; you can also estimate the wattage of a 240-volt heater by assuming 250 watts for each foot of heater.

Some baseboard heaters come equipped with a built-in thermostat and some require a separate thermostat. Some can even be wired into the home's central thermostat. If you're using the baseboard heater to even out temperatures, avoid connecting it to the central thermostat. If you do, it'll shut off when your main heating shuts off. The integral thermostat, if your unit has one, is second best, since it can be influenced by hot or cool air currents in the immediate vicinity of the heater and not necessarily the overall temperature of the room.

The most accurate way to control it is with a dedicated thermostat located on an interior wall. Typically, this requires a line voltage thermostat designed for baseboard heaters. Unlike the familiar low-voltage central thermostats that work indirectly to control your heating system, line voltage thermostats are wired directly into the power supply for your heater and allow or interrupt the power flow as needed. They're only appropriate for hard-wired baseboard heaters, which are usually 240-volt units, and aren't practical for 120-volt plug-in heaters.

Electric convection and electric hydronic baseboard heaters look basically the same. The differences lie in their initial cost and in their overall effectiveness. Choosing the best baseboard heater for your home could help you save money on utility bills.

Convection baseboard heaters are simply a high-resistance heating coil surrounded by fins or baffles that maximize the surface area that gets heated. Cool air enters the heater, is warmed as it's drawn through the fin structure and leaves the unit as warmed air.

Convection heaters are generally the least expensive to purchase. The units that don't rely on a fan are quiet, mechanically uncomplicated and reliable. They heat up quickly and, when shut off, shed their warmth just as quickly. Their inability to retain residual heat makes them the less efficient and ultimately less economical choice.

Hydronic baseboard heaters use electric heating coils or rods to warm a chamber filled with water, oil or some other special heat-transfer fluid. This makes them slower to reach full temperature, but once the target temperature is reached, the heated liquid holds and radiates that warmth long after the power is off. Hydronic baseboard heaters are generally more expensive to purchase than simple convection ones — often four to five times as expensive — but their operating economy soon makes up the difference.

Baseboard heaters work best when there is a free flow of air above and around them. Since they dominate the wall, furniture and draperies placed in front can interfere with their function and even present a fire hazard. Although most baseboard heaters are designed to be safe to touch, something falling onto a heater or draping over it can cause the unit to overheat. To prevent overheating, many models have a safety thermal shutoff that will respond by turning off the heater. Having these heaters at baseboard level presents a potential hazard to small children, so baby-proofing baseboard heaters is necessary.

In a dust-prone house or one with pet hair issues, you'll need to clean and vacuum your baseboard heaters regularly. Dust and pet hair scorched by the heating element can produce unwelcome odors and also inhibit the effectiveness of the heater.

Mounting the baseboard heater on the wall is the easy part. A few screws, possibly some drywall anchors, and you have it. The tricky part comes with the electrical connections. Even a simple portable, corded, 120-volt heater merits some advance consideration.

Unless it's one of the smallest units, the heater should be plugged into a 20-amp circuit; in many homes, those can be in short supply. It doesn't take many high-wattage appliances to trip the breaker, so you'll also need to consider what else is on the circuit. The 120-volt baseboard heaters are also considered the least efficient. Effective baseboard heaters require a 240-volt, 20-amp circuit — probably a separate dedicated circuit for each room you heat — and that circuit ideally should include a line-voltage thermostat.

The electrical complexity, including whether you have adequate electrical capacity in your home to accommodate electrical baseboard heaters, argues strongly in favor of a consultation with a qualified electrician. This is especially true if you plan to wire several heaters. A licensed electrician can tell you if the power supply to your house is suitable and whether you need additional circuits. If you do, he or she can safely and properly install them.