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Michael, Fans (and pumps) in TRNSYS set the downstream flow rate based on the input control signal and the rated flow rate parameter. They use the input flow rate only to check the fan mass balance. If you have 0 kg/h of air entering a fan because of the connections that you've made and the fan's control signal is set to 1 and its rated flow rate is 1000 kg/h then the fan will put out 1000 kg/h of air and log the time step as having a mass imbalance. Sometimes this is not a problem; for example if you have a fan that is blowing air from ambient into an air handler or into a building. You don't really care how much air is going into the fan and you can either ignore the warning or connect the fan's output flow rate to its input to suppress the message. If you have a supply / return system then it is probably more important to make sure that flow is balancing around the loop. Use a type65 and plot the flow rate out of each device in the loop. Make sure it all sums to the fan's outlet flow rate. Best, David On 12/4/2012 01:21, Michael Diekerhof
wrote:
-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com |