The answer to this question depends on a few factors, such as the size of your home, the number of people living in your home, and your typical water usage. Indirect water heaters are a great option for those who want to save money on their energy bill. They are also a great option for those who want to have a backup water heater in case their primary water heater fails. Indirect water heaters typically have a higher initial cost than other types of water heaters, but they can save you money in the long run. If you have a small home or live alone, a 30 gallon indirect water heater may be enough for your needs. However, if you have a larger home or live with multiple people, you may need a larger capacity indirect water heater. It is always best to consult with a professional to determine the best water heater size for your needs.