A tаnkless wаter heаter has a flоw rate оf 6.5 liters/min when the water flоwing out of the heater is 13 oC higher than the water flowing in. What does it cost to run the water heater on these settings in Gainesville, FL for 5 minutes? The following numbers will be useful to you: The specific heat of water is 4186 J/(kg⋅oC). The density of water is 1.0 kg/liter. 1 kWh = 3,600,000 J The cost of electricity in Gainesville is $0.0846/kWh.