Tankless water heaters save on energy but are no better at conserving water than the conventional tank heaters as it takes as long or longer for the hot water to reach the taps. To remedy this you can install a whole house circulating pump to give "on-demand" hot water. My question: Does the additional cost of installing the circulating pump system with the tankless water heater and the additional operating cost make sense ecomonically (also consider water conservation)? Or should the circulating pump be installed with a conventional tank heater. I am looking to replace my existing tank water heater that is 15+ years old. I'm heating the water with natural gas. I'm seeking advice.