Yes and Yes. Or maybe No and No. It does sound great but much to maintain in controls and equipment. The Tankless Water Heater is actually a boiler and a rather large one at that. In fact in many cases BTU/Hr rating will be higher than the boiler (or furnace) that will heat your home. My view, a tankless water heater is a solution looking for a problem. The only real justification is “standby heat loss” attributed to the tank type water heater. But with better tank insulation, that justification is fast disappearing and wasn’t even real if the water heater was within the heated envelope. There the water tank was just losing heat to the house which is heated anyway. And the boiler? The hot water is anything but instantaneous as the boiler goes through its purge and firing cycle, maybe just to rinse a dish in the kitchen sink. Actually many of the Tankless Water Heaters have added a tank just for this purpose; while small, are we back where we started?