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Meter Messenger #119 - Cool Your Hot Water Bill
June 15, 2012
How to Cool Your Hot Water BillIn this age of technological marvels like smart phones, hybrid cars and Web apps that run in the cloud it is easy to take simple home conveniences for granted. Consider hot water for example. We just don't notice it until it's missing - especially if taking a shower.
This take-for-granted convenience comes at a price - the cost of energy to produce it and the cost of repair to replenish service when an interruption occurs. We will limit our discussion to the energy cost portion of hot water service as it is second only to the heating and cooling cost found in most homes.
Hot Water Timer - Install an electric water heater timer to turn your hot water heater off at night when service is not required.
Insulate your Hot Water Tank - Install an insulation blanket around your hot water heater tank to increase thermal efficiency.
Insulate Hot Water Pipes - If under new construction apply a sleeve of pipe insulation to all hot water feeder lines but exclude risers from the feeder line to the fixtures. If construction is complete, try to insulate all hot water feeder lines that are accessible in the crawl space, basement or above ceiling tiles. Worst case, insulate the hot water line within six to eight feet of the hot water heater.
Install Heat Traps - These devices are simply check valves that install in the hot and cold water ports of the hot water tank and prevent heated water from seeping into uninsulated lines where it will lose Btu's.
Install a Drain Water Heat Recovery System - If you have six to eight feet of vertical drop in the primary drain line of your home you may benefit from installing a heat exchanger to extract heat from the drain water and use it to preheat the water going to your hot water tank. Higher incoming water temperature means less Btu's will be needed to reach the desired output temperature.
Install an Instant Hot Water System - Add a small circulation pump to the top of your hot water tank and use the cold water line from the last fixture in the plumbing loop as a return line. Circulate water through this loop during waking hours for instant hot water at every fixture. This saves both water and energy provided hot water lines are insulated.
Install a Tankless Hot Water System - If your hot water tank has trouble keeping up with demand, consider heating it instantly as it is needed. Whole house gas systems are recommended over electric because of the high amount of energy required in a short period of time.
Install a Heat Pump Water Heater - Using the same technology as a heat pump that heats and cools your home, a heat pump water heater uses only a third of the energy that conventional water heater does to get the job done. However, capacity and cost are important factors to consider.
Since energy costs for heating hot water are second only to heating and cooling the home, implementing any one of these suggestions should take some of the "heat" out of your energy bill.
Energy Monitor Rebates?There are various tax credits and rebates offered by federal and state governments for the installation alternative energy generation equipment. Many local utilities also offer rebates for the installation of high efficiency heating and cooling equipment, water heaters, window replacements and other energy saving improvements. The idea is to reward those who invest in reducing their energy usage because it lowers the utility's cost during peak periods and helps the environment.
Those who invest in an energy monitoring system and use the information it provides to reduce their energy consumption are doing the same thing. However, energy monitor systems are not included in the list of devices and appliances that qualify for tax incentives and rebates - yet!
I recently met with my local utility company and discussed the possibility of adding energy monitoring equipment to their energy efficiency rebate program. Since higher-end energy monitors do a very good job of tracking energy usage the approach suggested was to consider a rebate that is based on actual energy savings after the monitor is installed.
Using the documented savings, the utility would match a percentage of that savings with a rebate to their customer. Think of it as an employer contributing matching funds to an employee's 401K. The percent of contribution is yet to be determined and would be capped with a fixed period of time or a maximum dollar amount. Exactly how initial savings would be quantified also remains to be determined.
The idea was well received by the local utility and they expressed interest in elevating the concept to their power generation provider for further consideration. At this point, however, the concept is just in its infancy and must cross many hurdles before becoming a real program that delivers actual dollars to customers.
Challenges include finding a consistent method of measuring and tracking energy savings that does not favor one energy monitor manufacturer over another. Avoiding fraud is another concern - individual energy measurements would need to be reconciled with the total energy use through the utility's meter. Rebate percentages and time periods also need to be determined.
Benefits would lower overall energy monitor costs to consumers and accelerate payback periods. Consumers would have to act upon the information the energy monitor system provides in order to receive rebates. Once action is taken to reduce energy usage it tends to remain in place beyond the rebate period.
For example, replace incandescent lights with LED's or turn off that old refrigerator in the garage that is rarely used. Psychologists say that once a behavior is practiced consistently for at least three weeks it becomes a habit.
I encourage you to contact your local utility and ask them if they offer and type of incentive toward reducing the cost of an energy monitoring system. In most cases they will say no. Offer some of the suggestions outlined here. If enough voices speak up and ask the right questions we may just see rebates for energy monitoring systems become a reality in the future.
Fundamental DefinitionsAlthough many of you are familiar with fundamental electrical energy terms, some of you that are new to energy monitoring may still be struggling a bit to get your arms around how electricity is actually defined. Since it is something you cannot see or hear, to many, it remains shrouded in mystery.
Ohm's Law states that E = I x R where E is voltage, I is current and R is resistance. Power, in watts, is defined as voltage times current and energy reflects power used over time and is expressed as watt-hours or kilowatt-hours. To an electrical engineer these concepts are fundamental but to the average person they can get confusing. To shed some light on the subject, consider the "fireman" metaphor:
Picture a fireman spraying water on a fire. The water pressure in the hose represents voltage and the water flowing through the hose reflects current which is measured in amps. The restrictive diameter of the nozzle can be considered resistance and speed at which the water exits the nozzle is power. The total amount of water sprayed on the fire over time is synonymous with energy.
Another way of differentiating power and energy is to look at the speedometer-odometer relationship in your car. The speedometer represents power - an instantaneous reading of speed at a specific point in time. The odometer reflects energy as it shows the total distance traveled over time.
Energy monitors track energy or power used over time because it is what you pay for. They also show power to provide immediate feedback of consumption levels. On larger commercial and industrial accounts customers pay for the maximum amount of power drawn in a 15 or 30 minute period through a demand charge which can be as much as 30 to 40 percent of the electric bill.
Most energy monitors also track voltage which should normally run 120 +/- 5 volts for single phase power. As long as voltage remains in this range it is of little concern. However, if it goes higher (spikes) or lower (sags) sensitive electronic equipment may be subject to damage or unexpected shut down. Use of an uninterrupted power supply (UPS) of power conditioner can aid in preventing these voltage anomalies from reaching sensitive equipment.
Regardless of the type of power used; single phase, split phase or three phase, these fundamental definitions apply. Additional considerations for power quality include power factor and harmonics but are beyond the scope of our fundamental definitions here. If you'd like to learn more please visit the power quality section of our web site.
Ten Energy Saving Tips
1. Be sure that lamps or TV sets are not running in the vicinity of the thermostat. The heat they emit can affect thermostat temperature and cause cooling equipment to run longer than necessary.
2. Clean the lint screen on your clothes dryer before every load. Lint build-up slows air circulation. Reduced air circulation means more run time for the dryer.
3. Try to avoid running large heat generating appliances such as the range or clothes dryer during the middle of the day so they do not compete with the air conditioner. Use these appliances in the morning or evening when outdoor heat loads are less.
4. Thermostat set points cost money. For every degree you lower your thermostat below 78 degrees, cooling costs go up 3 to 5 percent. The same is true in winter for heating costs above 68 degrees.
5. Use bath fans and range hood fans prudently. They can expel a whole house of conditioned air in an hour of inadvertent operation.
6. When cooking on the range, be sure to use properly sized lids on the pans. The covered pan will bring contents to temperature more quickly and use less energy to cook the food than one left uncovered. Stove top clean-up is easier, as well.
7. Whenever you take a vacation for more than three days shut off the breaker to your hot water heater and shut off the water to your house. It takes more energy to keep 40 gallons of water warm for four days than it does to reheat it. Shutting off water can save a hardwood floor or carpet if the plastic water line to the refrigerator ice maker happens to rupture while you are away.
8.. Use your home energy monitor track the energy saving ideas your kids act upon. Take the savings from your electric bill and use a portion to bump up their allowance - when the energy is saved.
9. When checking food in the oven, look through the window instead of opening the door. A 20-30 degree temperature loss occurs whenever the door is opened briefly. In summer, the heat released must be removed by a heat pump or air conditioner adding the the energy load.
10. Do not oversize your water heater or add a second one unless you really need it. Remember, more gallons of hot water stored means more kilowatt-hours to keep it warm.
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