Humidistat in Ideal loads air system - not working?

asked 2020-06-18 02:55:08 -0500

Aravinda27 gravatar image

updated 2020-06-18 02:56:04 -0500

I am using Energyplus to simulate a room under various weather files. In the ideal loads air system, I set the dehumidification control type as Humidistat and Humidification control type as None, no outdoor air, and the rest to default with the appropriate schedule.

I set min rel humidity as 0 and max rel humidity as 65% in the Humidistat schedule. When the ideal loads air system is on and the rel humidity of zone is more than 65%, the system brings it to 65%, but after that, it keeps on reducing the rel humidity to less than 65% during the on-time of system, which is undesirable.

I checked with the outputs and the algorithm in engineering reference. The supply inlet temp to the zone is at supply limit conditions (13C ) and since it has to maintain the zone rel humidity to 65% and the suppl rel humidity cannot exceed saturation, the supply inlet rel humidity is set as 100%, thereby the zone rel humidity keeps on decreasing well below 65% due to the supply inlet conditions.

Does anyone know a way around this? I also believe this problem arises due to the absence of outdoor air but I don't want outdoor air.

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