Hello,

i wanted to buy a mini fridge. and cut out a hole through the door. . . then wire in (and insulate) a small PC fan to circulate the cool air throughout my drobe. it's small and would cool the room dramatically. how would i go about wiring a thermostat to the mini fridge plug. and probably the fan as well . . . so here's my idea.

any feedback is appreciated.

if your talking about one of those little blue mini firges that you can fit about 4 coke cans in, then its not worth bothering. they dont actualy have a heat pump system like propper friges but just work by blowing air over an aluminium matrix , this gets moderatly cool because of the "wind chill". so youd be much better of just installing more fans blowing over your plants. if your talking about a more propper sized (16*16*16+ inches ) fridge wich actualy has a heat pump then you could use this, but make sure you install the frige outside your growroom and duct the cool air in, as fridges just work by useing a compresor to state change the refrigerant gas and thus "pump" the heat out of the inside of the fridge and onto a hot element on the back. but to be honest these use at least 100w+ of leccy which would be much better of being used on a 40w rvk and 60w of suplimentary lighting, for example.
hope this helps,
josh

thanks a lot for the reply

i'll proably just get another fan and duct it to the grow room for more air circ. thnks again.

Actually, they do have a heat pump. Mini fridges sandwich a peltier (or TEC) between their cold plate and that aluminium heatsink+fan unit. A peltier does the same thing the compressor/coolant loop in a real fridge does, only in a much smaller package and horrendously innefficiently.

But you're right in saying the original idea won't work. Fridges don't "create cold", they just move heat around (i.e., from the inside of the fridge to the outside). Putting a fridge with a big hole in the door in a sealed box will will just move heat from inside the box to... inside the box. In fact, it'll actually warm it up in there slightly, as the compressor motor generates heat.

Also, putting a fan in a hole won't do anything either. Once it's depressurized the fridge to the point where the pressure difference between the inside and outside of the fridge is equal to the static pressure the fan generates, air will stop moving between them. You'd need an inlet and exhaust; one to suck in hot air, and one to blow out cooled air.

If you were really set on proceeding with this idea, you'd want to remove the compressor unit and coolant loop from the fridge, mount the flat passive exchanger on the back of the wardrobe, and the cold plate inside the wardrobe (ideally with a fan on it). Then you've saved a bunch of room, and also basically turned your wardrobe into a big fridge with crappy insulation. But the poor insulation isn't even the main issue, because if your wardrobe has enough air circulation going on to raise healthy plants, then it's just gonna dump all your cooled air outside again and you won't see much (if any) of a temp difference anyway. Fridges are sealed enviroments, so they don't have to deal with cold loss to exchanged air. Also, the thermostat will never see a temperature drop so it'll run the compressor on a 24hr duty cycle (which they aren't build for) and burn it out real fast.

So yeah, it's kinda impractical on a whole bunch of levels.

Hey USG 69!
I can really appriciate the need for cooling in a warmer environment! How about a proper air conditioner - but a small one. You should be able to find a small portable model or a small window model for under two hundred bucks (brand new), a lot less if you really shop around. Try a Salvation Army Thrift Shop, you might pick up a used one for $10. or $15.!!!

hey.
i really appreciate the replies . .really i do.
i understand how this whole project will not work. . i have been thinking about running an AC to the grow drobe. . just that. . my obstical is noise. . i have to be really quite. i ran the the cell phone charger to a pc fan.. i know how some of you might know how the fans are loud in general. . that's why i used a sealing foam. and a low voltage charger so my fan circulates air and stays completly silent. running an air condtioner might be too loud. i wanted to get one that you run the cool air through a ventilation duct. . is there such think. . . ? ? ? or is the ventilation duct i see in the back of one of those AC porable units just the exhaust for hot air? ? i'm not really at any obsticals now except space. . my grow drobe stays at a steady 75 F and 24C. . .especially since i added a humidifier. . .if i have to drop the temps. . i add cold water. . and it'll drop the temps steadily. . not too much. . but just enough. . .

thanks again for all the replies.

~USGrower69~

you cant really draw air through a fridge to cool it, as there is no fast acting heat exchanger. a fridge is an aircon, but is designed to keep working on the same air over time. it therefore doesnt run the air through a fast acting exchanger (radiator) it just cools its inside walls. air would rush through un-hindered.


you can grow in an upright. there light tight aswell for if you get company. you would need venting though and a thermostat chopping into its mains lead.

i saved a crop with a fridge once. just dragged it out from under there stairs, tipped it backwards 45degrees, and it filled with water like a dehummer. well...it is a dehummer. they still got some rot, but with no budgit they were more than happy