| Berkane, If you have the Tess Libraries, use one of the aquastat models. If you just have type 2, connect the upper input to the load temperature, leave the lower input temperature un-connected and set the initial value to 50. Connect the output control signal from the model back to the input of the same model for hysteresis. Set the upper deadband to 5 and the lower deadband to -5. Now the signal will be 1 when the temperature reaches 55 and stay at 1 until the temperature falls to 45. You can adjust the deadbands if you need tighter control but the tighter you make them the more the system will “chatter”. The likely reason you were getting an error with your equation based approach is that there are times that with the flow off the temperature is greater than 50 but with flow on it’s less then 50. There is no solution so the equation will flip flop until the iteration limit is reached. Jeff - TESS Sent from my iPhone On Aug 30, 2020, at 4:12 AM, berkane ahlem via TRNSYS-users <trnsys-users@lists.onebuilding.org> wrote:
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