1 – use type23 and airlink outputs to control the air flow rate. 2 – a straight duct does not generate air flow itself. Therefore its not an input and results from the pressure conditions in the network. 3 – this is very complex, because the flow controller does not perform this function and the distribution results according to the pressure losses. A simple solution is to work with two decentralized fans and to control them (see 1.). Von: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> Im Auftrag von ali shahrouzian via TRNSYS-users Dear all TRNSYS users, I am modeling a forced air furnace system to satisfy heating demands of a residential building. To simulate the building's thermal load and consider the effects of air transfer between thermal zones, I've used Type 56-TRNFlow. As you know, when TRNFLOW is turned on, in the simulation the defined infiltrations, ventilations and couplings will be replaced with the defined TRNFLOW data. Thus, in TRNFlow, I must define a fan, a heating coil, and a ducting system in order to model the forced air furnace system. However, I am having some trouble modeling a fan and fittings (Tee). 1- In TRNFlow, how can I control the value of a fan's air flow rate? My goal is to have the air blown into the building by a supply fan at a constant and certain rate. It seems that due to changes in pressure differences between auxiliary nodes, the air flow rate of the fan cannot remain constant either. 2- How can I input the value of the flow rate of a "straight duct" in TRNFlow? It seems that I can only input the values of the friction loss and the dynamic loss. 3- How can I model a diverging tee or a converging tee as an air link in TRNFlow. For example, as for diverging tee, if I want to send 30% of the flow rate in the main duct to the first branch and the rest to the second branch, how can I do this? I would appreciate it if anyone helps me in these cases. Best, Ali |