Water Heater Efficiency, Effectiveness and Safety
We all need some attention from time to time to not feel neglected and become depressed. Fortunately, appliances don't suffer from depression, but they really do need some attention from time to time. Hidden away in some dark recess of your home is the lowly water heater. It performs its assigned task quite often for more than a decade, with little attention or maintenance. Although it seldom complains, it could certainly benefit from a couple of changes and some routine maintenance.
The changes themselves are relatively simple and not beyond the skill level of the average homeowner by any means. Adding an insulating blanket can greatly reduce heat losses and reduce water heating costs by nearly 10%. For less than $30 and a half hours work, you can increase the insulation value of your water heater to nearly an R7. Since heating water is one of the largest energy consumers in a typical home it is well worth the minimal expense and effort.
Another relatively simple project to help maintain the efficiency and effectiveness of your water heater is draining the sediment that accumulates from the water. Close to the bottom of your water heater is a hose bib that allows you to drain water from your water heater. The typical recommendation is that this be done at least once a year, although that does depend on your local water supply. The hose bib at the lower part of your water heater makes connecting a short length of hose to a nearby floor drain relatively simple. You would then turn on the water and allow it to flow until it appears clear.
There are two opposing opinions on whether to shut the water off to the water heater when performing this task. One school of thought recommends turning the water off at the supply to the water heater, which would limit any leakages that might arise to only the water in the water heater. The second school of thought feels that water flowing into the water heater as it is being drained would further agitate the sediment and make the draining more effective. In either case, always remember to shut the power off to an electric water heater during the draining operation to not expose the heating elements.
A little more difficult is checking the anode rod installed in the water heater. These are also called sacrificial anodes. The reason being rather than your tank rusting, these take care of the chemical reaction in the water heater by sacrificing their own mass. On top of your water heater there will be a 1-1/16 inch hex head bolt. With both water and power off to the water heater, loosen and remove the sacrificial anode. The recommendation is that if it's coated with calcium or is less than 1/2 inch thick, it should be replaced. Follow the manufacturer's recommendations on installation, and you should be good to go.
Another way to help reduce energy losses is to insulate the supply lines themselves. Your local home improvement center or hardware store will carry self-sticking foam insulation to be installed on the pipes. You may not be able to reach all areas of the hot-water pipes, but the more you can insulate the less the heat losses. Your cold water supply lines will also benefit from insulation, as this will greatly reduce condensation and help maintain better humidity control.
Another common recommendation for saving energy is reducing the temperature setting for your water heater to 120° Fahrenheit. The upside to this is that for every 10° you drop the temperature you can save up to 5% of the energy cost to heat the water. Noting that there is an upside implies there is a downside. Water temperatures of 120°F will pretty well limit the risk of scalding but can also allow the growth of bacteria including Legionella pneumophila, commonly known as Legionnaires' disease. Remember that the 120°F temperature is only reached when the tank is both full and stable. As hot-water is drawn from the tank, cold water rushes in reducing the overall temperature. Between 95°F and 115 or so degrees Fahrenheit bacteria will thrive. At 120°F temperature bacteria are no longer active but are not destroyed. As contaminated water moves to the plumbing supply system, the temperature drops to a range where the bacteria can multiply and be distributed via your shower or other faucets.
To be safe from bacteria in the hot water-supply The American Society of Sanitary Engineering advises a temperature of between 135 to 140 degrees. Operating in this range will require scald protection. This type of protection can be provided right at the water heater by using a temperature activated mixing valve. This means that the temperature of the water at the point of use will always be less than 120°F.
Another option that provides better temperature control at the point of use would be an automatic compensating mixing valve. Either of these options means foregoing some energy savings for improved safety.