Tankless water heaters have a downside in that there's a minimum amount of flow before the heater turns on. I stayed at an Airbnb in Italy where I had to contin

Tankless water heaters have a downside in that there's a minimum amount of flow before the heater turns on. I stayed at an Airbnb in Italy where I had to continuously run the sink in order to take a warm shower that wasn't scalding hot or cold. I also had to run the bathroom sink to get hot water at all in the kitchen because the kitchen faucet alone wasn't enough to trigger the heater!