Hi You can used type 515 (Heating and Cooling Season Scheduler) if you have TESS licence. Alternatively, you can write an simple equation (assembely menue>new equation) to turn on and off your system considering the simulation time. For example if 5000(hr)>time >3000(hr), then dedicate 1 to an output parameter that represent the summer time for cooling system and link that parameter to the Chiller and other components. Hope it helps Mehdi From: trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] On Behalf Of ali javed hello dears |