mini fridge as HPA root chamber

Hello! Previously I tried to start a thread about my new HPA system but it got listed as spam and my account got banned. but here it goes again: I'm trying to get some input about using a mini fridge as the root chamber for a plant (or plants) that will aim to have a canopy surface of 26" x 16" (SCROG). After reading some of the contributions from treefarmer, trichy bastard, atomizer, etc. I realize that the temperature in the root chamber tend to be a problem, so I was thinking that maybe a properly ventilated minifridge will be ideal for this and it could also help to keep humidity under control by means of its evaporator. I'm thinking of 2 biocontrol for a 1.8cu ft minifridge will be enough room for the roots of a plant of the previously stated size, but I'm just eyeballing and I would like to know if I'm missing something. Thanks everyone!
 

Mike Young

Well-Known Member
You're not planning on plugging the fridge in are you? Average fridge temps run about 34-36 degrees. That sir, is waaay too cold for happy roots. I would find something else for a root chamber, perhaps a cooler. You could run a (pex) coil in the cooler & pump chilled water from the fridge through the coil. That would get you closer to the 65 degree mark that roots thrive in. Good luck.
 
I'm thinking of bypassing the fridge's thermostat and let a relay drived by a microcontroller set the compresor off (this, with the help of a thermal probe). But if that experiment fails must likely I'll reuse the fridge and go with Mike Young's idea (thanks Mike!). as a side note: my setup is based on microcontrollers, I'm learning how to use them and HPA looks perfect for this, you can save a lot on some expensive equipment by doinit yourself, ie; make your own dosatron (electronic version), timers, meters, etc. all those in a single and cheap device (plus redundancy).
 

Atomizer

Well-Known Member
If you`re into DIY, you can control the compressor using a cheap Velleman VM137 thermostat module (41F - 86F).
http://www.vellemanusa.com/products/view/?country=us&lang=enu&id=523193
Desolder and ditch the cheap 3A onboard relay, solder some flying leads to the coil outputs on the board to drive an external relay (12v coil, 240v 10A contacts). Solder some leads onto the ntc thermister so it`ll reach the inside of the fridge. Nothing to it :)
You can buy a ready made external freezer thermostat for about $75, but thats more than half the cost of your fridge.
 
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