We like tankless units. They’ve come a long way since their inception and can save you money without sacrificing a comfortable shower. You could simply invest in a larger water heater similar to the type you already have, or you can try a tankless water heater. If you do decide on a tankless unit make sure to purchase the gas fired type. The electric ones are slow to heat up and very expensive to operate. One thing to consider about tankless water heaters is gas supply. They use a great deal more fuel than a conventional water heater – about triple the amount. Because the tankless only needs to run when hot water is needed, and doesn’t have the constant pilot light, you end up using less energy. To convert to tankless you will probably have to increase the size of the gas line from your gas meter to the unit. This could be terribly expensive.