SimHVAC Maximum iterations warnings
My model whihc runs ok for design day simulations, when ran for weather file days give many Iteration warnings for VAV with REHAT box's. I have 5 VAV boxes and I am getting around 8 to 10 warnings - few of which are as below:-
** Warning ** SimHVAC: Maximum iterations (25) exceeded for all HVAC loops, at RUN PERIOD 1, 03/28 16:40 - 16:50
** ~~~ ** The solution for one or more of the Air Loop HVAC systems did not appear to converge
** ~~~ ** Air System Named = VAV WITH REHEAT did not converge for mass flow rate
** ~~~ ** Check values should be zero. Most Recent values listed first.
** ~~~ ** Demand-to-Supply interface mass flow rate check value iteration history trace: 4.427527E-002,4.367028E-002,4.334135E-002,4.394626E-002,4.427539E-002,4.367029E-002,4.334158E-002,4.394676E-002,4.427527E-002,4.367028E-002,
** ~~~ ** Supply-to-demand interface deck 1 mass flow rate check value iteration history trace: 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,
** ~~~ ** Air System Named = VAV WITH REHEAT did not converge for humidity ratio
** ~~~ ** Check values should be zero. Most Recent values listed first.
** ~~~ ** Demand-to-Supply interface humidity ratio check value iteration history trace: 9.052790E-008,9.673507E-008,9.731781E-008,9.111049E-008,9.052739E-008,9.673596E-008,9.731832E-008,9.110991E-008,9.052790E-008,9.673507E-008,
** ~~~ ** Supply-to-demand interface deck 1 humidity ratio check value iteration history trace: 1.237439E-004,1.236712E-004,1.235623E-004,1.236351E-004,1.237441E-004,1.236711E-004,1.235622E-004,1.236349E-004,1.237439E-004,1.236712E-004,
** ~~~ ** Air System Named = VAV WITH REHEAT did not converge for temperature
** ~~~ ** Check values should be zero. Most Recent values listed first.
** ~~~ ** Demand-to-Supply interface temperature check value iteration history trace: 5.214427E-003,5.149490E-003,5.110221E-003,5.175149E-003,5.214442E-003,5.149493E-003,5.110250E-003,5.175208E-003,5.214427E-003,5.149490E-003,
** ~~~ ** Supply-to-demand interface deck 1 temperature check value iteration history trace: 0.236625,0.236953,0.235742,0.235414,0.236626,0.236954,0.235743,0.235416,0.236625,0.236953,
** ~~~ ** Air System Named = VAV WITH REHEAT did not converge for energy
** ~~~ ** Check values should be zero. Most Recent values listed first.
** ~~~ ** Demand-to-Supply interface energy check value iteration history trace: 1067.752024,1053.156244,1045.222737,1059.816714,1067.755021,1053.156433,1045.228238,1059.828629,1067.752024,1053.156244,
** ~~~ ** Supply-to-demand interface deck 1 energy check value iteration history trace: 326.375391,-337.225776,325.235144,-335.177758,326.375846,-337.226459,325.236864,-335.180489,326.375391,-337.225776,
** ~~~ ** Node named VAV1 BOX OUTLET NODE shows oscillating humidity ratio across iterations with a repeated value of 1.438061E-002
** ~~~ ** Node named VAV1 BOX OUTLET NODE humidity ratio [kg-water/kg-dryair] iteration history trace (most recent first): 1.438061E-002,1.438068E-002,1.438061E-002,1.438068E-002,1.438061E-002,1.438068E-002,1.438061E-002,1.438068E-002,1.438061E-002,1.438068E-002,
** ~~~ ** Node named VAV1 BOX OUTLET NODE shows oscillating mass flow rate across iterations with a repeated value of 0.180034
** ~~~ ** Node named VAV1 BOX OUTLET NODE mass flow rate [kg/s] iteration history trace (most recent first): 0 ...
Here are some answered questions about these warnings:
1. VAVTemplate-Maximum iterations exceeded
2. exceeding maximum loop iterations
3. DOAS input Problem
4. VAV System Not Converging.
If you don't find any of those answers helpful, you might want to refine your question to be more specific.