So I am looking for some advice regarding equipment sizing for my grow situated in a really hot and dry area.
I plan on a perpetual harvest using 4 of the 650W LED’s and 1 480W QB.
The grow is sealed and situated inside a room with concrete walls which are insulated with PUF panels.
My heat load of the lights will be around 10,510 BTU’s (650x4+480) X 3.41
I have a minisplit AC which is rated for 2 ton ie 24000BTU, however I chanced on this video of Cannabis Mechanical, he says the total BTU of an AC is divided amongst heat removal and water removal.
At lights off, since the heat of the lights go away, the RH will spike. The AC will be able to cool the room to its set temperature faster and will cycle off leading to a cold and wet climate.
Is there any way I can fool the AC into registering the wrong indoor temperature so that it stays on and continues the dehumidification, is the CoolBot suitable for my need?
I am looking to control my energy usage so not really looking to get a dehumidifier.
Another option I have and will be considering is to periodically exhaust the room at lights off since the outside air is dry enough, but I would like to know if the AC thing is doable, since I dont really want to bank on the hybrid sealed room.
So
Is the AC enough for my light load?
Can I hack a minisplit into reading a wrong temperature so that it stays on and I can utilise the dehumidifcation
Any other tips you might have about HVAC in general for a grow situated in hot and dry area looking to minimize energy usage.
energy requirements for this task don’t change (much) because you’re using a different machine to perform the task… unless you also change the thermal capacity of water (let us know if you solve that one…).
if you simply lie about the temperature, what would you expect your AC to do?!?
I’m just curious what set points are you trying to achieve in your room. Ie temp and rh
I would look at how/when your watering your plants as well. Maybe try to get more of your irrigation done earlier in the day cycle and have a more aggressive dry back so your plants aren’t transpiring as much water lights out.
I would just buy a used dehu. You’re about to play yourself for no reason. Keep in mind if your room is sealed what’s going on outside your room will play a lesser part the tighter your room is.
It’s not going to work. Piece of shit anden has let me down multiple times, and my mini split will do a relatively good job at preventing a nightmare, but it’s not a solution.
In order to turn an A/C into a dehum you need to add some kind of reheat on the outlet to bring the air temp back up. As you lower the air temperature it’s moisture holding capacity (relative humidity) goes down so you won’t actually make any progress lowering humidity by cranking your A/C. That’s why the air coming out of a dehum is warmer than when it went in.
In industries like grocery stores where failing to control the humidity can lead to condensation on the floors and slip-and-fall accidents they’ll often add reheat kits to their A/C units even though there’s some controversy about whether or not this is better/cheaper than just adding stand alone dehums.
Below is a diagram of how a typical dehum is setup. You can see it contains mostly the same components as a standard A/C system just arranged differently. An A/C system has the condenser (red) mounted separately in order to reject the heat out of the workspace. In a dehum they use that heat to their advantage by placing it in the outlet to supply the reheat in order to facilitate dehumidification.
When they rig a standalone A/C with a reheat kit to enable dehum mode (can’t dehum and cool at the same time) they will typically add either electric heat strips or a propane/natural gas burner in the A/C outlet. Like I mentioned, there is some controversy as to whether this is better/cheaper than standalone dehums.
Or Google “office dehumidifier,” and hardline it to a water line and add sensors to auto feed your humidifier when it’s empty.
Imo I think the mini split should be turned into a chiller for a rotovap or just used as is for an a/c
Edit: if you do it right you could most likely find a way to filter the exhaust and loop the filtered exhaust water back into the dehumidifier until that empties fully.
But you have to make sure that the dehumidifier you get has a port to fill it externally and slide a drawer for filling. The one posted most likely doesn’t have an external fill port.
Second Edit: could take a chance with a used one that’s cheaper than the one posted and drill a water inlet for the exhaust water which could be filtered through a standard Pentek/Pentair filter or an under the sink filter … Could make it more active and have it so that you can pump it with a peristaltic or diaphragm pump.
Good info here. Most do not understand what has been explained in this thread.
Equal cooling plus heating produces dehumidification.
That is the basis of the facility I designed, built, and operate. Hot and cold fan coil units handle, cooling, heating, and dehum with no standalone dehums. HID lights for more heat production and heat recovery chillers to heat hot water hydronic system for almost free.
So if you have an ac like a mini split you can add a heater on a humidistat for humidity control. You also want an overtemp switch on the heater and maybe a timer for night operation.
