Hi everyone! I am simulating an existing building with a cooling split unit, using HVAC:Template:Zone:PTAC with a SingleSpeedDX with no dehumidification unit added. However, when I look at the results, there is a huge drop in absolute humidity indoors compared to outdoors (about 10g/m3). Can anyone explain me why or how can I avoid that?
Thank you in advance!!
A DX cooling coil removes both sensible (temperature) and latent (moisture) energy from the air stream. Water cooling coils also have this same property. When using a cooling coil in your simulation roughly 25% of the energy transfer will be moisture. So the result will be that the indoors are dryer than outdoors.
Thank you for your answer! Do you know if there is any way to simulate a cooling unit which removes only the sensible energy and not the latent?
Well, I've never tried this but you could make the SHR = 1. You must ensure that the total capacity and air flow inputs result in a supply air condition that is on the psychrometric chart (i.e., outlet air RH < 100%).
Coil:Cooling:DX:SingleSpeed,
1.0, !- Gross Rated Sensible Heat Ratio
Thank you now it works just fine!!
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