A method for control of a HVAC installation with a heat source and with at least two heat exchangers (10, 11, 12) connected to a pump operable to generate a pressure resulting in a fluid flowing through said heat exchangers (10, 11, 12), wherein the heat exchangers (10, 11, 12) each comprise an adjustable, electromechanical valve (7, 8, 9) each associated with a temperature sensor, and wherein each of the valves (7, 8, 9) is operable to modulate flow through its heat exchanger (10, 11, 12) between an open position giving flow of a fluid through the heat exchanger (10, 11, 12) and a closed position giving no flow, wherein the valves (7, 8, 9) and the pump connect to a controller such that the controller is configured to adjust and to monitor the positions of each of the valves (7, 8, 9) and is configured to adjust the pressure generated by the pump, the method comprising the steps of: adjusting each of the electromechanical valves (7, 8, 9) to a position different from its closed position, each of the valves (7, 8, 9) taking a first temperature measurement and after the first temperature measurement taking a second temperature measurement, determining for each of the valves (7, 8, 9) a temperature rise quantity as a function of the results of the first temperature measurement and of the second temperature measurement, determining and recording a limit position for each valve (7, 8, 9) as a function of at least one of said temperature rise quantities, adjusting each of the electromechanical valves (7, 8, 9) to its limit position, lifting the limits for the positions of each of the valves (7, 8, 9) to an upper limit position, lowering said pressure generated by the pump while monitoring valve positions for each valve (7, 8, 9) by the controller until one of the valves (7, 8, 9) approaches or substantially approaches its upper limit position, characterized in that the temperature rise quantity is determined by using a mathematical model assuming a temperature rise function r(t) = T 0 (1-e -t/τ) as a function of time t, wherein T 0 denotes a target temperature and τ denotes a time constant of temperature rise, wherein the time constant τ of temperature rise is determined by obtaining at least the first temperature measurement and the second temperature measurement in relation to valve position and/or flow. adjusting each of the electromechanical valves (7, 8, 9) to a position different from its closed position, each of the valves (7, 8, 9) taking a first temperature measurement and after the first temperature measurement taking a second temperature measurement, determining for each of the valves (7, 8, 9) a temperature rise quantity as a function of the results of the first temperature measurement and of the second temperature measurement, determining and recording a limit position for each valve (7, 8, 9) as a function of at least one of said temperature rise quantities, adjusting each of the electromechanical valves (7, 8, 9) to its limit position, lifting the limits for the positions of each of the valves (7, 8, 9) to an upper limit position, lowering said pressure generated by the pump while monitoring valve positions for each valve (7, 8, 9) by the controller until one of the valves (7, 8, 9) approaches or substantially approaches its upper limit position,