Boilers are devices in solar heated hot water systems in order to finally heat the usage water by heating the water in solar collectors and circulating through flexible metal hoses located in a tank and used as serpentine.

Due to pressurization problems and freezing events that take place in systems which usage water is the same with the water circulating in the collector system, hot water systems with boilers are advantageous comparing with the systems without boilers which usage water is directly heated.

Using flexible metal hoses as serpentine in boilers has many advantages as efficiency resulted from high surface area comparing to steel pipes, installation ease for their flexibility and high corrosion resistance of stainless steel to corrosion and lime.