images of electric room heaters

Risks of Improper Use of Electric Room Heaters

Electric room heaters, or space heaters, have gained popularity in recent years due to rising heating costs and clever marketing ads that claim incredible energy savings by using these heaters. The problem is that many of these heaters are not used as intended which reduces the savings or the electric circuit in the house is not properly rated which can be dangerous.


Proper Use

The intent of room heaters is to add extra heat for individual rooms that you wish to be at a higher temperature than other rooms in your house. For example, if you spend a larger portion of your time in the living or family room, then you may wish for the temperature to be comfortable in that room while allowing the rest of the house to be at a lower temperature to save energy. Another way to think of the intended use of these heaters is as portable zone control, allowing some rooms to be warmer.

The most common misuse of room heaters is using one or more heaters to heat the entire house, replacing a more efficient option of a gas furnace. Electric heat is more efficient at converting energy to heat than other energy sources, however, it is also more expensive. On average, electric heat will cost twice as much as natural gas. Contact us to discuss efficient heating systems to meet your needs.

Additionally, if the room heater is near the thermostat then the main furnace will not function properly. You may need to have the thermostat moved to a more suitable location if you utilize room heaters.


Power Consumption

Contrary to what is stated in the advertising, room heaters consume large amounts of power during use. A quick look at the label on the back or bottom of the unit will provide you with the rated power. Most heaters operate at 120 volts, 60 Hz, 1500 watts. The watts is the power consumed during use and what you are billed for by the utility company.

For information on how electrical energy is calculated, see article How to calculate electric energy cost of common household items.

I’m not saying that these companies are lying to you, but many of the statements are misleading. For example, one ad claims the heater consume the same or less power as a coffee pot. Good deal, right?, because coffee pots don’t use much energy. Wrong! Many coffee pots are rated at 1200 – 1500 watt, which is the same amount of power as the electric heater. However, we don’t think of a coffee pot using energy since it is generally only on for a few minutes each day; whereas the heater will be on for many hours of the day.


Electrical requirements

It is strongly recommend to have an electrician inspect the wiring and circuit protection in your house before buying or plugging in a room heater. The following are areas that David or James will check during an inspection.

1. Available dedicated circuit rated at 20 amps with proper size wiring and breaker (or fuse).

A 20 amp circuit may seem high but keep in mind that a single heater operating at 1500 watts has a current draw of 12.5 amps (1500watt/120volts). Wiring and breakers are sized based on current. It would seem that at 12.5 amps that the 20 amp circuit would still have 7.5 amps available. Unfortunately, that is not the case as breakers and fuses are rated at 80% capacity, which in this case is 16 amps. If any other devices are on the same circuit then overloading of the circuit is likely which will cause the breaker to trip or the fuse to blow.

2. Is the wiring the proper size throughout the entire circuit?

Sometimes different size wiring will be connected together on the same circuit and may cause a larger size breaker to be used where a smaller size is more appropriate (20amp breaker used instead of 15amp). The breaker rating should be sized based on the smallest wire size in the circuit. This is a particularly dangerous situation as the wire size for a portion of the circuit may be undersized and if the circuit amperage is too high for the wire size then the wire may become hot and cause a fire. Unfortunately, this can be difficult to detect in some installation if the wiring is not accessible.

3. Is the wiring in good condition?

Where possible to inspect, the wiring and insulation surrounding the wire will be check for possible damage or degradation.

4. Is the outlet in good condition?

The outlet body and cover plate will be inspected. If broken, then outlet or cover should be replaced. The fit of the plug into the outlet will also be check to ensure a snug fit. As cords are plugged in and unplugged many times over, the outlet socket wears out. A loose fitting outlet will cause the outlet or cord to overheat and damage the outlet and cord plug end. This is a potential fire hazard.

5. Is the outlet 3-prong?

Most heaters use a 3-prong plug which includes the ground connection to carry away harmful electricity in the event of an electrical short inside the heater. The outlet providing power to the heater must be 3-prong and should be grounded back to the service panel. If the outlet is the older 2-prong type then replacement with 3-prong type is required.

6. Do not use 2-prong adapters.

There are serious concerns with using an adapter to convert a 3-prong grounded cord to a 2-prong plugin. First, the heater will not be grounded, see item 5 above. Second, the adapters are not rated for the continuous current that the heaters use and will overheat. Best case the damage is limited to the cord or outlet, worst case is a potential fire.  Third, the two prong adapters do not hold the plug firmly into the outlet. Problems similar to a loose fitting outlet as described in item 4 are likely.

7. Check the cord plug end on used heaters to ensure the prongs and molded rubber are in good condition.

The cord end will be inspected to check for damage due to overheating or bent prongs. The length of the cord will be inspected to check for any nicks or cuts in the insulation. If damaged, then the cord should be replaced.


Manufacturers Warnings

Read manufacturer’s warnings and the provided owner’s manual. Additional information can typically be found on a tag on the cord.

When buying and installing an electric space heater, you should follow these general safety guidelines:

  • Electric heaters should be plugged directly into the wall outlet. No extension cords or power strips.
  • Do not use 2-prong outlet adapters.
  • Buy a unit with a tip-over safety switch, which automatically shuts off the heater if the unit is tipped over.
  • Do not route cords under carpet or rugs.
  • Maintain clear distances recommended by manufacturer.


If you have any question or concerns regarding use of room heaters please contact us.


Thank You,

David McGill
James McGill


Article written by Tim McGill, editor @ Tree Branch Publishing.

electrical meter

How to calculate electric energy cost of common household items

Electricity from the utility company is delivered to your house and connects to a meter that measures the amount of electricity used. The electricity is sent through the meter and routed to the service panel which split the electricity into the circuits throughout the house to power the appliances, lights and wall outlets.

Each month the utility company collects this usage information from the meter to determine how much electricity to charge you for. Electrical power is measured in watts and is charged by the kilowatt-hour. Kilowatt-hour is simply how many 1000′s of watts are consumed per hour.

Let’s review all the terms you need to know to understand electrical cost.

Kilowatt is watts in units of 1000 (1 kilowatt = 1000 watts).

Watts (wattage) are calculated by multiplying the voltage by the current.  (Voltage x Current = Watts)

Kilowatt-hour (kWh) is how many 1000 watts are consumed in a one hour period.

Utility Rate is the cost per unit of electricity, measured per kWh (kilowatt-hour).


Calculating Electrical Energy Cost

To calculate energy cost the “kilowatts” are multiplied by “time in hours” x “utility rate”. The average utility rate for electricity in southern Iowa seems to range between 11 -14 cents per kWh. I’ll use 12 cents for the calculations.

Just a quick note on time, since the rate is based on hours, converting minutes to hours may be required for calculation purposes (Total usage time in minutes/60 = hours). For example: 45 minutes would equal .75 hours.


Let’s look at two examples for calculating energy cost:

Example 1 – 60 watt light bulb

The power consumed by the light bulb is 60 watts, or .06 kilowatts. Using the utility rate of 12 cents per kwh, each hour of use will cost slightly under 1 cent ($.0072) If the light bulb is on for 10 hours per day then the cost per day is 7 cents for that single bulb (.06kw x $.12 x 10 hours = $.07).  Considering how many light bulbs operate in a household it’s easy to see how the lighting cost per month can add up to a few dollars.

For example: I have 6 recessed 65-watt light bulbs in the kitchen that were on today for 16 hours – I like to hang out in the kitchen. The total wattage for all the light bulbs is 390 watts, or .39 kW. At 12 cents per kilowatt-hour, my cost for lighting the kitchen today is $.75. If that were a typical day, then my projected monthly cost would be $22.50.  Time to rethink leaving the lights on!


Example 2 – Space heater

The typical wattage of a space heater is 1500 watts. In kilowatts that equals 1.5 kW. Using the 12 cent kWh energy rate, the cost per hour for the heater is 18 cents. That doesn’t seem like much until you consider how that adds up over time.

Hours per day

Cost per day

Cost per Month

5 hours



10 hours



15 hours



20 hours




Use the below calculator to estimate electrical cost for your devices.


Calculating Amperage

Sometimes you need to know the ampere draw of a device, especially for determining the correct circuit size. If you know the wattage then you can determine ampere draw by dividing the wattage by the voltage.  For example, the 1500 watt heater plugged into a 120 volt circuit will draw 12.5 amps (1500/120 = 12.5).


If you would like assistance with determining the energy cost or ampere draw of various devices in your house, please contact us. We are happy to help.


Thank You,

David McGill
James McGill

Article written by Tim McGill, editor @ Tree Branch Publishing.

Dirty vs. Clean Air Filter

Why it’s important to replace your furnace air filter regularly.

Myth #1 – The main purpose of the furnace air filter is to keep the air clean in the home.

Myth #2 – You should buy the best filter available.

Both of these statements are false, or at minimum, only partially true.

First and foremost the purpose of a furnace filter is to protect the furnace from damage caused by dust, lint, or foreign objects that find a way into the airstream. Without filtering, these particles may cause damage to the furnace or, at a minimum, reduce the overall furnace efficiency; which will cost you more in energy. Filtering prevents dust and other particles from collecting on the heat exchanger causing excess heat inside the furnace; clogging up the air conditioning coil which reduces the air flow to the house and causes the blower to work harder; or collecting on the fan blade or blower motor causing it to overheat or have electrical damage. Repair of any of these items is expensive and can be avoided by ensuring a filter is in place and receives regular maintenance.

A secondary purpose of the air filter for many households is to improve the air quality by filtering out dust and other small particles, such as pollen.  However, the furnace is not designed as an air quality device so you may not be getting the benefits from a premium air filter that you are led to believe you’re getting. More on that topic in another article; this article is focused on the primary purpose of protecting the furnace.


A clogged filter may cause damage to your furnace.

Dirty vs. Clean Air Filter

Dirty vs. Clean Air Filter

So we established that a filter is needed to protect the furnace, however that same filter may actually cause damage if not maintained. When the air filter gets clogged with dust and other particles, the air flow through the filter is restricted and damage to the furnace and AC unit is likely.

  • Blower (fan) motor failure is common. The restricted air flow causes the blower motor to work harder. This reduces the life of the motor and may cause it to fail, i.e. burn-up. The “burn-up” simply means the motor overheats, which often results in permanent damage to the internal electrical windings or other components. Replacing a blower motor is a common repair and can cost $200 – $500 in parts and labor.
  • In summer months, restricted air flow through the AC cooling coils inside the furnace unit may cause the unit to drop below freezing temperature and “ice up”. When ice forms on the fins of the coil inside the furnace compartment, then the outside air unit must work harder; this may damage the compressor. When the ice melts inside the furnace compartment, the water may cause damage to electrical components or over longer periods of time cause metal to rust and deteriorate. In the best case scenario the iced-up coil can be fixed with a service call. If other components are damaged, then significantly higher repair costs can be expected.

If that’s not reason enough to maintain your air filter, consider the extra energy cost due to reduced efficiency when the air flow is restricted.

The good news is that these costly repairs can often be avoided by replacing, or cleaning if reusable type, your air filter on regular basis.  How often depends on the type of filter, the usage of the furnace, and the conditions in the home or business. More on how frequently to maintain your air filter is discussed later, first let’s talk about the different types of filters.


What type of air filter do I need?

While there are many different types and grades of filters available, most are effective at filtering larger particles, which is the primary concern for protecting the furnace. Refer to your furnace owner’s manual for the manufacturer’s recommendations for type and size of filter to use. The original furnace manufacturer is the best source of information on the type of filter to use as each furnace is designed for a given air flow and using the proper filter will help maintain that air flow. If you are not sure what your manufacturer recommends then contact us. We will evaluate your system and suggest a filter that will meet your needs.

As a general rule, for newer model furnaces the pleated filters work well at trapping the airborne particles. However, for an older style furnace, the pleated filters may be too restrictive on the air flow and thus a woven fiberglass filter is a better choice.


How often do I need to maintain the filter?

How often depends on the type of filter, the usage of the furnace, and the conditions in the home or business.

  • A higher efficiency filter will need replaced more often since they are better at trapping particles and tend to clog up faster.
  • During peak operating months the filter may need replaced more frequently than during months of lower usage. Remember to check your filter during summer months as well.
  • The environmental conditions of the home or business may require changing the filters more often. This is often true during a remodeling project when dust is more prevalent, or if you are sensitive to allergens.
  • Pet owners should consider changing filters more often as pet hair will tend to collect on the filter and cause it to clog up.

A general rule is check the filter monthly and replace (or clean if reusable) if needed.



If you need assistance with replacing your furnace filter, please contact us and we’ll be happy to send a service technician to you.

Thank you,

David McGill and James McGill

Article written by Tim McGill,editor @ Tree Branch Publishing.