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Re: [EnergyPlus_Support] HVAC error



The coil inlet air temperature is already 12.3C, why is the cooling coil 
inlet temperature so low? Is cooling really needed at this time? What 
are the zone temperatures? Report the cooling coil node inlet 
temperature and any other node temperatures upstream of the coil to 
determine why the air is so cold. Also look in the csv file at time 
01/11 8:00 and see if the coil is actually on. I have seen before where 
this error occurs and the coil was not actually on (and this may have 
been fixed, I can't recall). In that case you could ignore the warning.

fady_sherif_adly wrote:
>
> Hello all
>
> I have a problem with modeling HVAC systems for my simulation. I'm 
> trying to simulate a normal residential flat and my problem is twofold;
>
> a) I don't know which fields to use to most closley approximate a 
> normal split type air conditioning unit found in homes.
>
> b) I keep getting the following error messages when I use a thermostat 
> object, a Zone:Unitary object and a System:Unitary object like it says 
> in the "getting started" .pdf file:
>
> ** Warning ** Coil:Cooling:DX:SingleSpeed "MY ROOM SYSTEM COOLING 
> COIL" - Full load outlet air dry-bulb temperature < 2C. This indicates 
> the possibility of coil frost/freeze. Outlet temperature = 1.38 C.
> ** ~~~ ** ...Occurrence info = YEAR, 01/11 07:45 - 08:00
> ** ~~~ ** ... Possible reasons for low outlet air dry-bulb 
> temperatures are: This DX coil
> ** ~~~ ** 1) may have a low inlet air dry-bulb temperature. Inlet air 
> temperature = 12.320 C.
> ** ~~~ ** 2) may have a low air flow rate per watt of cooling 
> capacity. Check inputs.
> ** ~~~ ** 3) is used as part of a HX assisted cooling coil which uses 
> a high sensible effectiveness. Check inputs.
>
> This error message is repeated over a thousand times for different 
> occurances and zones.
>
> Can anyone help?
> Thanks for your time.
> Fady Sherif Adly
>
> 

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

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