What are the advantages of using an immersion heater at the top of a water tank?
Firstly there is no advantage except if you are drawing water from the top. Thats because if you are not drawing water from the top, then the water at the surface that is in direct contact with the immersion heater will evaporate! :shy:
If you are referring to a statndard electric water heater for a home, a two-element heater usually has a lower-temperature heater at the bottom and a higher watt-higher temperature set at the top. As maverick stated, water is usually drawn from the top.
THe lower element preheats most of the tank to, say 110 degrees, and the higher one will heat the upper third to 130 degrees. Overall this is more efficient since less energy will be wasted keeping all 80 gallons at the higher temperature while the whole family is sleeping (and heat radiates out of the heater).
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