Whether they are the answer, dependson the question. They are smaller than a regular tank, they require the same size room for combustion purposes, they require larger electric wires or gas lines and a larger flue. The amount and temperature of the water will depend on the quantity going through the heater. If the heater has a flow control to limit the amount of water going through it in order to keep the temperature high, then multiple users may find a lessened flow to compensate.: I am thinking of buying a a tankless water heater. They are relatively new around here. Are they the answer? What brands should I look at? What size would I need? I have a older home with three full baths. We tend to do alot of things at once such as showering, dishwaser, and clothes washing. :