1) A flow speed of minimum 0,5 meter per second (prefered value 1 to 1,4 meter per second). Circulaion flow pass in 30% to 50% of the total number of the warm water supplying plates. 2) Maximum operating temperature: 248°F, Minimum operating temperature: 35°F, Typical pressure loss at rated flow: 0.7 PSI, Maximum working pressure: 232 PSIG