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It may just be difference in perception.
With the tankless, the hot water appears at the faucet after around 10 seconds, but it is fully heated hot water.
With the tank hwh, I got warm water in about the same time frame, but it takes 30 seconds or more to get fully heated hot water.
The reason is that the tank hwh has hysteresis, so the actual temperature will vary a few degrees, typically in the range of 4 F. So if the thermostat is set for 120 F, it will heat to 122 F, then not reheat until temperature drops to 118 F. So if you draw water when it is close to 118F, the water will be warm but not hot for a while, until it reheats.
People compensate for this by setting the temperature higher - but that is less energy efficient.
With the tankless, the hot water appears at the faucet after around 10 seconds, but it is fully heated hot water.
With the tank hwh, I got warm water in about the same time frame, but it takes 30 seconds or more to get fully heated hot water.
The reason is that the tank hwh has hysteresis, so the actual temperature will vary a few degrees, typically in the range of 4 F. So if the thermostat is set for 120 F, it will heat to 122 F, then not reheat until temperature drops to 118 F. So if you draw water when it is close to 118F, the water will be warm but not hot for a while, until it reheats.
People compensate for this by setting the temperature higher - but that is less energy efficient.
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