By James Dulley, Published September 11 2009
Steps can make aging water heater efficientDear Jim: My electric water heater is 18 years old but still works and makes enough hot water. I want to reduce my water heating costs. What can I do to make my water heating more efficient other than installing a new one?
– Sandi T.
Dear Sandi: New water heaters are more energy efficient than old ones, but there is no need to replace an old one that is not leaking. The electric water heater in my own house is 22 years old and still going strong. I have made some improvements to it so it is more efficient than when it was new.
Electric water heaters are simple devices. There generally are two electric resistance heating elements, top and bottom, in the water tank. The bottom one is used the most to keep the tank water hot. When the tank starts to run out of hot water, for example after many long showers, the top element comes on instead to supply hot water faster.
From the standpoint of using electricity to heat the water, all electric water heaters, even the old ones, have nearly 100 percent heating efficiency. The differences in the overall efficiency and your water heating costs are determined by how much heat is lost from the water tank (called standby losses).
With old water heater tanks, the lower heating element has to come on often just to make up the heat lost through the poor insulation to the utility room or basement air. The most energy-efficient new electric water heaters have many inches of high-R-value insulating foam in between the water tank and the outer skin.
The efficiency of most older water heaters can be increased by adding tank insulation. You can easily test your water heater tank to see if it needs more insulation. Put your hand on the water heater tank near the top and then on the top. It will probably be warm, which indicates it is losing heat.
You can purchase water heater insulating jackets at most home center stores. These wrap around the tank and cover the top. I used old Fiberglas batt wall insulation to wrap my water heater. I put the paper vapor barrier to the outside and covered this with construction foil to also block radiant heat loss.
Your water heater probably does not have heat trap fittings in the inlet and outlet pipes as new water heaters do. Hot water naturally circulates up into the pipes above the water heater. There, it loses heat and drops back down. Put tubular foam insulation over the pipes immediately above the tank or have heat trap fittings installed.
Install a water heater timer to switch it off, typically during the daytime when away working, and back on in the evening. The water will stay warm enough for most tasks. Set the thermostats under the heating element covers so the water is about 120 degrees at the kitchen faucet.
Check with your utility company about incentive programs if you allow them to install a timer that they can control during peak usage periods. Every several months, drain a gallon of water from the valve at the bottom of the tank to flush out sediment.
Dear Jim: I had a new high-efficiency air conditioner installed last fall. This summer, the house is cool, but the air seems to be too humid for good comfort. Is there anything I can set differently so it works better? – Kay N.
Dear Kay: This problem can happen with a high-efficiency air conditioner and a single-speed blower. There really is nothing you can change yourself. A contractor can set the blower speed lower, but it may sacrifice some efficiency.
When installing a very efficient central air conditioner, it generally is best to also install a variable-speed blower and compatible thermostat. This will allow you to control the humidity level as well as the temperature.
Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com