The DX coil model tests the available capacity with the coil off and then with the coil on to get the "No load" and "Full load" capacities used for determining PLR. This means that if the DX coil does not need to operate, the warning will be tripped even though the coil is off. This will be corrected in a future version of EnergyPlus. For now, report the DX coil air inlet node temperature and compressor PLR to see if the DX coil is actually on when the inlet temperature is below 2C (you may need to use a detailed reporting frequency if the air temperature is very close to 2C when the DX coil operates). If the DX coil is not operating when the air temperature is below 2C, disregard the warnings. If the DX coil is actually on, you can count the number of times the coil operates below 2C.
khaysepro wrote:
I am getting the following warning, and I can not seem to locate its source. The hourly reports do not indicate that coil is at full load at any point during the hour in question. This unit has a high outside air load that is driving the coil inlet temperature down at times. Does this warning get generated whenever the entering coil temperature is low regardless of whether the coil is cooling or not?
** Warning ** Coil:Cooling:DX:SingleSpeed "CLASSROOMB- ZONE PTAC COOLING COIL" - Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.20 C.
** ~~~ ** ...Occurrence info = Columbia Metro AP SC USA TMY3 WMO#=723100, 01/18 13:00 - 14:00
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 = 20.111 C.
2) may have a low volumetric 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.
*************
************* ===== Recurring Error Summary =====
************* The following recurring error messages occurred.
*************
************* ** Warning ** Coil:Cooling: DX:SingleSpeed "CLASSROOMB- ZONE PTAC COOLING COIL" - Full load outlet temperature indicates a possibility of frost/freeze error continues. Outlet air temperature statistics follow:
************* ** ~~~ ** This error occurred 23 times.
************* ** ~~~ ** Max=1.952314 Min=0.474338
*************
************* EnergyPlus Completed Successfully- - 30 Warning; 0 Severe Errors; Elapsed Time=00hr 00min 13.61sec
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