Horticulture Grow Room Cooling

[jmk0407]

I am working on a plant grow warehouse consisting of 40 grow rooms to be maintained at 72 deg. F, 45% RH. I am looking at cooling each "bloom room" using a packaged 7 ton DX unit with modulating hot gas reheat and variable speed digital compressors for cooling and dehumidification. Each bloom room will contain 15 1,000 W light bulbs, that will be on for 12 hours and off for 12 hours. I am concerned about when the time the lights are off and overcooling the spaces to maintain RH. Also, I don't have an accurate estimate of the latent load in the space. The compressors are capable of a turndown to 10%. There will be no outside air to the units - they will be 100% recirculating. Am I barking up the wrong tree with the DX units or is more information required?

 

[jmk0407]

Is modulating hot gas reheat available during low-ambient conditions also? I have yet to hear back from the manufacturer, so I just want to see if this is even an option.

 

[EnergyProfessional]

It really depends on how tight this has to be... plants in nature go through large swings of RH and temperature. so the grow rooms may allow wider swings.
Keeping exactly 72°F/45% with plants hat need OA and produce water is not realistic.

 

[chicopee]

Why would you want to turn off and on all lights at the same time? Why not turn off some of the lights to control temperature, thereby, minimizing the modulation of burners. I would suggest that you speak to vendors or manufacturers of your proposed heaters about modulating burners. I remember that in the 80's, Cleaver Brooks had oil burners on their boilers capable of turndown ratios of ten to one (10:1). By latent heat load, I am assuming that you are referring to the transpiration of plants, so I would suggest to research horticulture text books.