Hello, The problem seems to be, that although a lot of air is entering the bottom zone, the pressure doesn’t rise in the zone. So there isn’t a pressuredifference between the two zone. The flow through the crack is now temperature driven. If I add heating in both zones, the flow through the crack is almost zero. Greets, Marielle Van: trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] Namens Mariëlle Nuchelmans Hello, I have a problem regarding trnflow (version 16). I have got to model the following: An atrium 2 zones heigh A mechanical ventilation systeem, supply in the bottom zone, exhaust in the topzone (temperature 18 degree celsius) I made a simple model: EN – AN – FA – CR – FA - EN Outside – temperature 18 degree – fan into bottom zone – cr between zones - exhaust fan to outside - outside Problem is that when I plot the flow through the crack, the results doesn’t made sense. For example: the fan delivers 120 kg/h, through the crack goes 25000 kg/h?? Crack has a Cs of 1 kg/s at 1 Pa. If anyone got any ideas where to look for the solution, please let me know. With kind regards, Mariëlle |