Dehumidification Controls

[natalie_p]

I normally do Dehumidification during Vent and Cooling Mode, so I stage on compressors and Hot Gas Reheat to maintain cooling setpoints. A customer request unit that can do dehumidication during heating mode as well. So should I stage on compressors and reheat to maintain heating setpoint?
Another questions that I have is, why some control engineers bring on cooling to maintain Humidity level in the space but some bring on cooling to maintain a low suction pressure during dehumidification?
Please help
Thanks
Natalie

[flange]

You must understand that simply raising the discharge air temp artificially "shows" dehumidiifcation simply by changing the psychometric conditions of the airstream. Actual dehumidification is accomplished with mechanical cooling or chilled water cooling. The reheat is to give you a false load so that you do not overcool the space while trying to lower humidity levels. As far as providing dehumidification while heating, you actually already are, but possibly not enough. As in the previous case, by heating the airstream, you change the psychometrics and lower humidity levels. If you nee further dehudimidifcation you could use mechanical but there are other ways to do it such as a wheel. I guess the real answer to your question is that every situation is different, equipment is different, and you need to plot your conditions on a psyche chart to see where you need to head to get to the desired conditions.

[DeltaT]

What exactly is your application?

[natalie_p]

What exactly is your application?

It is a Constant Air Volume unit for a Grocery Store.
Thanks

[stanbyyourword]

sounds like you are using discharge gas from med temp rack as reheat , so in turn i would say you would tap off common liquid line med temp , for this dehumidification ,which all sizing would have to be calculated for rh load regards stan