Central AHU outlet air condition problem

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Thank you for your reply! In the AirloopHVAC:UnitarySystem I used Fan:VariableVolume element. I checked the air mass flow rate and it's always different from zero, it vary from 14 to 26 kg/s. In Design:Specification:OutdoorAir I created a schedule for each zones, but the schedule can be only 1 or 0, for example I cannot insert 0,2. There is a way to solve this problem?

The Design:Specification:OutdoorAir object tells E+ the "maximum" OA per zone, although a schedule can be used to change that maximum based on time of day. The Controller:MechanicalVentilation object is used to tell E+ to modulate OA based on other inputs (occupancy or IAQ).

Thank you rraustad! I solved this problem and now the OA is in function of the real zones occupation. Now I have some problem with "SimHVAC: Maximum iterations (20) exceeded for all HVAC loops" I read a lot of previous discussion on the possible causes and I tried to fix the most common causes (only one fan in the air loop, SetpointManager after the coils) but the problem persist and I have more than 900000 warnings. There is something else that I can try?

SimHVAC warnings usually occur when the SA temperature and/or flow rate are changing each iteration of a single time step while the simulation tries to converge. Try using constant fan mode to see if that helps. Also try using a constant SA temperature set point for the main air loop cooling and heating coils to see if that makes a difference.