A compact, on-demand system to produce high pressure (5,000 psig) and high temperature (450 C.) water or other liquids which maintains single-phase flow throughout the system utilizing low-cost, thick-wall tubing and thereby negate the requirement to design the unit as a boiler or adhere to coded pressure vessel design requirements. This design can also replace a conventional boiler for the generation of hot water as well as low and high pressure steam.

A compact, on-demand system to produce high pressure (5,000 psig) and high temperature (450 C.) water or other liquids which maintains single-phase flow throughout the system utilizing low-cost, thick-wall tubing and thereby negate the requirement to design the unit as a boiler or adhere to coded pressure vessel design requirements. This design can also replace a conventional boiler for the generation of hot water as well as low and high pressure steam.