Climaticly Controlled Room Help.

[jeffreyjay]

Hey fellow techs..

I am looking to dehumidify a small (132K cu ft)section in a warehouse to store electronics. The room has a new ten ton roof top HVAC system. I'm told I can add a heating element to the a/c to basically get them both to run at the same time to dehumidify the room but I don't know how the controls are supposed to function...any advice, comments or suggestions greatly appreciated! Thanks! -Jeff

[incontrol]

Usually dehumidification is for human comfort not storage. Are you talking about electric duct heaters? If the room needs cooling then the A/C runs. If the humidity is high then the A/C runs to remove moisture and the heater reheats it. By lowering the temperature you are inadvertently raising the 'relative' humidity. I've got an operating room they want at 65 deg and 50% humid. Cooling a room down that far makes the 'relative' skyrocket. So the more you cool it the more you may have to reheat it. Expensive. If this is adjacent to an unconditioned space, one important consideration is room pressurization. Mainting a slight positive pressure will keep out external humidity. If you just put a RTU in a room and turn it on the circulating air will creat a negative space. You will need to program in a high limit point for the reheat when actual heat is not needed.

PS. I've always wondered about using the Voyagers as dehumid because the coil is before the heater but I'm not sure if that would wreck it. Can't get an answer out of Trane.

[jeffreyjay]

Thanks! Lots of good stuff. I read a story recently about an OR, It got deep! Excellent point on the duct heater high limit safety, thank you, exactally the stuff I'm looking for. I'm kind of new to dehumidification-very interesting. I'm in San Jose but our facility is in Chicago right on the lake. I tried to rent some dehumidifiers over there and got laughed at! The pressurization is interesting, got me thinking as traffic is low (We store oncology equipment). Tell me more about the RTU/fans (I just put three 56" ceiling fans in) causing negative pressure??? Let's chat! -Jeff

[mrhvacmechanic]

Incontrol makes some good points. Also keep in mind most warehouses do not have any kind of good vapor barriers.
I have work in some facilities that store electronic gear, and usually the room is designed for environmental control. I suggest you get a qualified contractor to seal the floors and surounding wall of the area in question.
You may have to build a small room inside your warehouse,depending how crucial the electronics are and if its in your budget.