Looking to buy a kenmore 20 gallon water heater.110 has 2000 watt element 220 has 4000 element.I was told either way they will use the same amount of electric just the 220 will heat up more quick .Is this the case.I ask because sister said she had a 110 dryer once and electric went through the roof.Also the 30 gallon and larger water heaters have the yellow label giving you the yearly cost at a set KWH rate along with the energy factor.now on the sears site they don't even have this info for the 20 gallon but it does have the same insulation R value and that being 16 so could I assume the energy factor is about the same.