A system and method of providing a high temperature hot water system assembly including a direct buried valve box that connects to one or more underground service pipes is disclosed. The buried valve box contains a valve assembly configured to control the flow of water through the one or more service pipes. An air gap within the valve box allows for movement and expansion of the components as the temperatures rise, preventing cracking or other failures. A bypass valve is also provided within the buried valve box, allowing for a small amount of hot water to flow through the service pipes to gradually increase the temperature. The direct buried valve boxes, controllable through valve risers that terminate in surface assembly boxes, eliminate the need for large, concrete underground vaults that make maintenance and operation of valve assemblies more difficult.