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Staying with the tank

Posted by on August 15, 2011

About seven years ago, Lisa and I remodeled the kitchen at our home on Parkview Drive.  The one big thing that I got to add to the project was a Bosch Aquastar natural gas tankless hot water heater.  Too bad it was hidden behind the refrigerator.  I’ll never forget the plumber who did the installation.  He had never seen a tankless hot water heater, and he refused to take out our old hot water tank since he knew that there was no way the tankless system would work.  Surprise!  It worked great, and I was excited that we would have the same opportunity to change out the electric hot water tank at our new home, but those plans changed.

Per the EPA heating water can account for about 15% of the home’s energy use.  Keeping 20 to 80 gallons of hot water around the house is not very efficient; plus, using electricity to do it is even more inefficient.  In doing some studying online, I found the efficiency of tankless hot water heaters has gotten even better with a couple of models listing almost 84% efficiency.  I was estimating about $2k for the purchase and installation of a new tankless propane heater.

I have decided to stick with our current inefficient electric hot water tank at least until it dies.  There were a lot of things that brought me to this decision.

The first one was about a month ago when I met Luke, the founder and president of Plotwatt.  Luke told me that Duke Energy offered “time of use service” rates.  Not in my 26 years as a Duke Energy customer had I ever heard of Duke Energy offering this rate system.  So I sent my contact at our new utility, Randolph Electric Coop, an email and inquired if they offered this type of service.  REC does offer a “time of use” rate.

Time-of-Day rate is simply based on the time of day in which you consume electricity.  Consumers pay a lower rate per kWh during periods of low demand and a higher rate per kWh during periods of peak demand.  With REC, the off peak rate is .049 kWh instead of the usual flat rate of .12 kWh.  With a little research I discovered a GE hot water timer at Home Depot for less than $40 bucks.

I was not comfortable completing the installation process by myself.  The directions looked fairly straightforward and simple, but I asked a good friend with more electrical experience to come over and assist.   In about an hour I had a timer, half the size of a shoebox wired into the hot water heater.  Now the hot water heater only has power about ten hours a day, and no power during the peak utility hours from 2 to 8 PM.  I also invested and installed for about $20 in a R11 hot water jacket.

Once Plotwatt syncs to my home system, I will be able to monitor the actual cost of running our hot water heater.  However, I think it will take a very long time to justify the $2k investment of a new tankless hot water heater.


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