errors simulation because of the HVAC System

asked 2016-11-21 09:35:34 -0600

Flow78
21 ●1

updated 2017-05-06 08:30:14 -0600

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

Hi all,

I try to run the simulation but I have 31 errors because of the HVAC system. Some errors are like this one :

UpdateZoneSizing: Cooling supply air temperature (calculated) within 2C of zone temperature ...check zone thermostat set point and design supply air temperatures ...zone name = AHU 1 ...design sensible cooling load = 1784609.90 W ...thermostat set point temp = 0.000 C ...zone temperature = 26.719 C ...supply air temperature = 26.667 C ...temperature difference = -5.24004E-002 C ...calculated volume flow rate = 15182420.16951 m3/s ...calculated mass flow rate = 18182663.80103 kg/s.

Or like this one :

CheckWarmupConvergence: Loads Initialization, Zone="AHU 11" did not converge after 25 warmup days. ...Environment(SizingPeriod)="BALTIMORE BLT WASHNGTN INTL ANN CLG .4% CONDNS ENTH=>MDB" ..Max Temp Comparison = 4.60E-004 vs Temperature Convergence Tolerance=0.40 - Pass Convergence ..Min Temp Comparison = 1.93E-006 vs Temperature Convergence Tolerance=0.40 - Pass Convergence ..Max Heat Load Comparison = 1.0000 vs Loads Convergence Tolerance=4.00E-002 - Pass Convergence ..Max Cool Load Comparison = 6.0292E-002 vs Loads Convergence Tolerance=4.00E-002 - Fail Convergence

But I don't understand how to resolve them. If someone can help me that can be cool !

Thank you.

Florian,

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answered 2016-11-21 11:38:12 -0600

rraustad

13804 ●79 ●12 http://www.fsec.ucf.edu/

updated 2016-11-21 11:41:01 -0600

These two warning are likely not related.

The first warning is suggesting that the difference between the zone temperature and supply air temperature is too small which can lead to extremely high zone air flow rates. If the zone temperature is 26.7C, then a likely choice for supply air temperature would be at least 5C lower or no greater than 21.7C.

The second warning relates to how the simulation is warming up and converging on the initial conditions. For some reason, the successive simulation of this model does not converge on the same cooling and/or heating loads. However, the comparison between the actual and the tolerance is not that great at 0.06 vs 0.04 so you can probably disregard this specific warning.