Indirect Water HeaterIndirect water heaters store water that is heated by a boiler. The main benefit of using an indirect water heater is that many of them have a lifetime warranty as they are not subjected to the harsh conditions under which gas or electric water heaters operate when mixing cold water and hot metals. Indirect water heaters retain heat better than traditional gas water heaters. As the hot water is produced by the boiler, they have a higher output than electric water heaters. If you are considering installing a new, efficient low-water volume boiler, you should also consider implementing an indirect water heater.