What is the required backflow protection for a solar heating system that is chemically charged and includes an expansion tank?

The required backflow protection for a solar heating system that is chemically charged and includes an expansion tank is a reduced pressure principle assembly. This type of backflow prevention device is specifically designed to protect against both backpressure and back siphonage, which is essential in systems that contain chemicals or fluids under pressure, such as in solar heating applications.

In a chemically charged system, the potential for contaminants to be siphoned back into the potable water supply is a major concern. The reduced pressure principle assembly operates by maintaining a pressure that is lower than the supply pressure in the system, effectively preventing any backflow from occurring. This makes it suitable for systems that involve expansion tanks, where pressure fluctuations may happen, as it can handle the risks associated with these conditions effectively.

This method of protection ensures that any backflow that may happen due to pressure differentials or system failures does not contaminate the potable water supply. Thus, the reduced pressure principle assembly is considered the appropriate choice for safeguarding both the system and public health in this scenario.