An Item that you can use for both tanked & tankless water heaters is a Chili Pepper pump. http://www.chilipepperapp.com/howit.htm . Space saving, endless hot water (Think lots of people) are major advantages to a tankless heater along with energy savings of not having to maintain a tank full of hot water. But the cost of the heater, Branch circuit / Panel upgrade or gas piping up sizing, flue venting change and water treatment for water with a total hardness greater than 12 grains can be very high and should be included in a comparison of Price Vs. Value. Some other things to take into consideration would be, No Power No Hot Water, No Power No Freeze Protection and no Emergency Water Storage. Lee