With the Eberspacher Camper hot water kit, how long after you turn the tap on in the shower at a flow rate 5lpm will the water last at 40°?

This Eberspacher S3 D5E heater kit for providing domestic hot water solutions for shower, sink etc will provide continuous hot water once the heater coolant circuit is at full operating temperature. The exact outflow temperature at the shower head would be dependent on initial temp of cold water supply, and the mix ratio at the heat exchanger mixer valve - please take a look at a sample water circuit attached