1.   Water Heater problems.  Your water heater is a large user when it runs. Leaks and/or thermostats set too high raise your costs quickly. Whether it’s a leaky faucet in the house or a cracked pipe under the house, it causes the water heater to stay on more. The thermostats should be set at 120 degrees. An insulation wrap placed on the water heater traps heat and shortens run time. A popular “feature” on new homes is “instant” hot water in the home, so that you don’t have to “wait” for the hot water to reach you when you turn it on. This is usually done with a small pump that is installed on the water heater to circulate water that has “cooled” in the pipe back to the water heater and keeping hot water at the faucets. The pump itself does not use much energy, BUT—if the hot water pipes are not insulated, it pumps hot water from an insulated tank through pipes with no insulation and allows it to cool then sends it back into the water heater to be reheated (usually by 4,500 watt elements).  Be sure hot water pipes are insulated.

2.   Clothes dryer located in the conditioned part of the home.  The dryer has a powerful fan that whips air past the damp clothes to dry them, then vents it to the outside. If the dryer is in the conditioned part of the home, that’s house air that your air conditioner has worked to cool and dehumidify being sucked out at a rate of 150 to 200 cubit feet per minute (cfm). In a 1500 square foot house with eight-foot ceilings, a 200 cfm dryer can empty a house load of air every 60 minutes. That air can be replaced by hot humid air leaking into the home through kitchen and bathroom vents, fireplace vents, around windows and doors, recessed light fixtures, plug & switch plates etc. For that reason it’s best to locate the dryer in  an un-cooled utility room or garage.

3.   The old refrigerator that still works is in the garage, where it’s hot.  Old refrigerators are not very energy efficient. Plus, if it’s in a hot garage it can run almost continuously. Your new refrigerator can be two or three times  as efficient, especially if it was manufactured after January 1, 1993. You’re much better off keeping everything in the newer refrigerator and unplugging the old one.

4.   Swimming Pool Pumps.  Cost is determined by the size of the pump and the amount of time it runs. A timer for the pool pump is well worth the installation cost. It can pay for itself through energy savings in three months or less.

5.   Thermostat set too low.  Your air conditioner does not cool faster at a lower setting. It only runs longer. The recommended summer setting is 78 degrees. Each degree below that increases run time by 5 to 7 percent. You can conserve energy if you raise the thermostat a few degrees while you are away, but just move it back to the original setting when you return.

6.   Thermostat not calibrated.  For example, you “think” you have it set at 78 degrees, but it may be cooling the home to 75 degrees. This increase in run time increases your cost (see #5 above). You can check for this problem by placing an accurate thermometer on the thermostat to verify, then compensate on the setting.

7.   Blower set “ON” at the thermostat.  It should always be set on “Auto”. If it is set in the ON position it pushes air through the ductwork continuously even though the compressor cycles on and off. When the compressor is running it removes moisture from the home. If the fan continues to run after the compressor cycles off it reintroduces moisture back into the home. By setting the switch to AUTO, humidity is kept lower, your cost is lower, and your comfort is higher. If your ducts are leaky, (and most are), the ON setting is especially bad.

8.   The air conditioner filter is clogged. The system is designed to move the same amount of air back through the filter that comes in through the supply ducts. If the filter is clogged the airflow is restricted. A clogged filter reduces efficiency of your air conditioner and can lead to costly repairs. Change the filter at least once a month. More often if you have pets in the home.

9.   Evaporator coils clogged with dust. This, like the clogged filter, restricts airflow. When the unit is running it draws air from the home through these coils to remove heat. If the coils are dirty your comfort goes down and your cost increases.

10. Heat Pump cooling and heating at the same time. This problem can easily triple your cost. It can be caused by a variety of thermostat and wiring problems, or malfunctions in the unit. When this happens you have TWO large loads switched on that are working against each other. This increases run time for both, and your cost increases tremendously.

11. Heat strips stuck on.  This is another problem that causes a huge increase in cost. Because of a thermostat, control wiring, or other wiring problem the heat strips can remain on even though the system is turned off. This means that the heat strips, ranging from 5,000 to 20,000 watts are coming on even though the fan is off. Even if the high temperature safety switch turns them off occasionally they come back on as soon as they cool. 

12. Air conditioner not getting enough air returned from the house.  There are a lot of causes for this. For example, if the return grille is in the floor and is partially or completely covered by a rug, or furniture, such as couches or chairs placed over the return grille. Also, sometimes the return grille is on a lower wall and airflow is restricted in this way.  This results in inadequate volume of air getting back to the coils, which lowers efficiency and shortens the life of the unit.

13. The ceiling lacks adequate insulation.  Without proper insulation heat from the attic is conducted into the house. Your air conditioner is running, trying to remove the heat. The amount of time the air conditioner runs is increased. If your home does not have enough insulation in the attic, increasing it to the proper level can be one of the best investments you can make.

14. Mobile Home floor insulation has fallen out or been torn out by pets.  It’s bad enough that the insulation is not there to prevent heat transfer to and from the home, but it may be even worse that the ductwork that was installed at the factory is not protected. This is usually a rectangular shaped “box” of very thin sheet metal that runs lengthways under the home. If the insulation is missing it is exposed to outdoor conditions, so the temperature of the “supply” air moving into the home changes in relation to the severity of outdoor conditions. Remember, HEAT moves from hot to cold, and the wider the temperature difference the faster that happens. In the summer you’re moving cool air through ductwork that is surrounded by warm, outside air. In the winter you’re moving heated air, and the ductwork is surrounded by cold air. When conditions are the very worst outside, and when you need relief most inside, are the times this problem works against you the most.

15.  Crossover/connector duct that connects ductwork of the two sides of a double-wide mobile home disconnected.  This is a very common problem, usually caused by a piece of flex duct that joins the two sides together. Because the tape fails, one end falls off and all of the conditioned air for half of the home is “wasted” under the home. There are even times when both ends of this duct are off. At other times both ends are still connected but the ductwork is broken in the middle.

16.  Supply duct leaks.  Conditioned air moves through the ductwork and into your home. Any conditioned air that is lost before it reaches the inside of your home is wasted. Your unit has to stay on longer so your cost goes up. Poorly sealed ducts can cause 10 to 30 percent of your operating costs.

17.  Return air leaks.  As mentioned in #8 above, the system is supposed to move the same amount of air back through the return that it brings in through the supply ducts. All return air should come from the conditioned part of the house. A very common problem is that the unit is drawing air from other sources back through the return. An example of this is when the air handler is in a closet that is not sealed, so it draws air from the attic as well as the home. Lower wall returns are notorious for leaks unless there is a sealed plenum between the grille and the air handler. Another one that is very common is when the air handler is in the garage on a plywood box that is not sealed, so unconditioned and unfiltered air from the garage is drawn into the return. It is also very common to find mobile homes with package units where the return duct is disconnected or has holes in it. All of these result in higher operating cost and lowered comfort levels.