Everything Ed is saying is exactly what I said, the temperature of the water will depend on the flow. With less flow the water stays in the heater longer and absorbs more heat from the burner. Turn up the flow and water stays in the heater less time and absorbs less heat, you get cooler water. In reality you may not need to, or want to, turn on the cold faucet, you can adjust the temperature by regulating the flow with the hot water faucet. Down side, you may not get a strong shower!
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