Re: [EnergyPlus_Support] Humidity Issues

["Michael J. Witte" <mjwitte@xxxxxxxx>]

A schoolroom with a DX unit in Houston with continuous fan operation and 
outside air with no humidistat control?  You should expect high humidity.

Your original run has 2 autosized DX coils in series.  EnergyPlus autosizing is 
not able to understand this.  It will size each coil to try to meet the 
specified supply air temp within the constraints of the capacity/airflow 
limits.  

If you decide to run on humidity control, it will work fine with 
COIL:DX:CoolingBypassFactorEmpirical, no need to use the multimode DX coil.

Why is the wet bulb temp rising after the cooling coils?  The gas heating coil 
is coming on.  I don't understand the control approach on the gas heating coil. 
 If you can't figure this part out, please ask again.  SET POINT 
MANAGER:SCHEDULED:DUALSETPOINT is not intended for this type of control.  

Mike



On 29 Jan 2007 at 12:48, Richard Raustad wrote:

> I suggest you revert back to a single cooling coil. Manually size this 
> coil if autosizing does not give you the performance you desire. You 
> won't get the same performance as a single coil. You must also add a 
> humidistat if you want to use humidity control and change the 
> Dehumidification Control Type to CoolReheat and the Run on Latent Load 
> input to Yes in DXSystem:AirLoop. I believe you will also have to change 
> to Coil:DX:MultiMode:Empirical using 
> CoilPerformance:DX:CoolingBypassFactorEmpirical objects for this to 
> work. Just use 1 cooling stage and 1 dehumidification stage. As for your 
> last question, the wet-bulb temperature should not increase across the 
> second cooling coil in your example file. If the second coil is off, the 
> wet-bulb temperature should be the same as that leaving the 1st cooling 
> coil. If the second coil is on, the wet-bulb temperature should always 
> be lower than that leaving the 1st cooling coil.


========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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