[Equest-users] Dehumidification issue - REPOST

[Daniel Knapp via Equest-users]

Hi Jason,

A couple of thoughts which may or may not be helpful: 
>  
> So my questions are: 
>  
> 1.       How does eQUEST control the maximum humidity allowed in the supply airstream?

The DOE2 dictionary states that the humidity is controlled by measuring the relative humidity in the return air stream. You have an hourly report of the humidity ratio. Have you checked how this translates to a relative humidity in the return air stream? 

Also, does the VAV system you are modelling have a central heating coil? i.e. have you entered a “Hot Deck Max Leaving Temp” under the Heating Coil Cap / Control tab? Without an input for this entry eQUEST does not create a central heating coil. Without a central heating coil the system may not be able to cool and reheat to dehumidify the air which may prevent the system from turning on dehumidification in the absence of a cooling load. 

> 2.       How could one possibly explain a cooling load/consumption without any cooling set point schedules in any of the zones supplied by my system and zero moisture removed from the air?

VAV systems are controlled by default to supply cool air at 55ºF at the central system level and then reheat as necessary to meet zone set points. It’s possible that the system could be cooling the supply air even in the absence of zone cooling loads simply to meet its supply air temperature control requirements. 

Hope that helps, please feel free to share your input files if you’d like someone to have a closer look. 

All the best,

Daniel

—
Daniel Knapp PhD, P Phys, LEED AP
danielk at arborus.ca

Energy Efficiency Expert
Arborus Consulting
2-43 Eccles Street
Ottawa ON K1R 6S3
(613) 234-7178