We had 3 eighty gallon propane hot water heaters that were over 18 years old. Everyone said they were working on borrowed time. We decided to go with Rinnai and have been very pleased. We were able to go with just 2 units for our 11 bedrooms by using the system with the water storage tank. We've been using the system for over 9 months and everyone has been very please. No one has every been short of hot water and there has been no delay in the water getting hot either. We also feel more secure with the Rinnai heaters than we did with an old hot water tank in the attic like we had before.