The standby losses are pretty easy to approximate. The losses are the surface area of the water heater (in sq. ft) times the temperature difference between the air outside the water heater and the water inside the water heater (in F) divided by the R-value of the water heater's insulation. This will yield BTUs/hr of heat loss.
As an example, let's assume the following:
Radius of water heater: 10 inches
Height of water heater: 50 inches
Water temperature: 120F
Air temperature: 75F
R-value of water heater's insulation: 16 (units are such to make the result come out in BTUs/hour)
BTUs per kWh: 3412
Cost of electricity: 13 cents per kWh
For this example, the standby losses should be on the order of about $24 per year.
Quote:
Originally Posted by HABckb
Since my Rheem water heater is approaching 10 years in age I am considering having a tankless electric water heater installed instead. I am aware of the cost for electrical hook up as well as cost of the tank but am wondering what thoughts others have in regard to this consideration. I find it a waste of money to have water being maintained at temperature in existing 40 gal tank and thought a tankless system in the long run would be more efficient as well have a longer longevity. thoughts appreciated.
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