i am looking to install a takagi tankless water heater that will provide approx 4.5 gpm on demand. I am considering placing an additional tank heater of 50 gallons in front of the tankless heater. will this work. would the tank heater provide hot water to the tankless heater at the proper temp, and when exhausted it would send cooler water to the tankless which would then kick in and provide additional hot water on demand. let me know what you think