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KaptKid said:
Glad you guy's are along for the ride.

People on other sites have talked about this but that was all, talk.
All the DIY teks were for a/c's as cooler's. Thats alot elect.
I belive this will run about $15 a month.


So for I spent:
trash can $15
pump $50
everything else I had or found.The refeg was given to me.

Still need to add two values to the outside for water control.
Need about $2 more in parts. Its Sunday or I would of gotten the parts.

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Just so you know, standard A/C's and Refrigerators run the same vapor compression cycle using nearly the same refrigerant. This means that at the very best the refrigerator is going to have the same COP (coefficient of performance) as the A/C. If you have the same amount of heat to remove (ie same grow setup, same reservoir size, etc.) then you are going to use the same amount of electricity to remove the heat with either the refrigerator or the A/C unit.

Now, refrigerators are usually designed to slowly remove heat, as they usually only have to maintain the temperature of a small volume, high thermal inertia, highly insulated space. You also have a much less efficient heat exchanger design both on the evaporator as well as the condenser coil (ie they both rely on natural convection rather than forced convection, smaller surface area heat exchangers, etc) as well as a smaller, less efficient compressor/valves/pipe runs, resulting in a lower COP. This means that not only is the refrigerator a smaller capacity heat pump, but it is also a less efficient heat pump.

Now here comes the kicker, when you try to feed too much heat into a small heat pump and exceed it's rated capacity, it will only remove heat at its maximum rated capacity, meaning that the airspace inside the refrigerator will continue to heat up, resulting in the refrigerant eventually overheating to the point that phase change in the condenser coil is impossible with the given heat exchanger, and the refrigerator goes from a heat pump utilizing a phase change vapor compression cycle to an extremely inefficient closed loop gas radiator...which also poses problems with refrigerant pressures exceeding what the piping was designed to handle, and can result in catastrophic failure of the piping system, potential shrapnel, exposure to an air-displacing refrigerant that, when exposed to the overheating parts of the refrigerator, may thermally decompose into highly acidic and highly toxic hydrogen fluoride as well as highly toxic carbonyl halides.

I have had this idea many times before and through careful research and a highly technical background in HVAC/R systems, I have determined that the main reason people opt with the A/C systems is that the system is properly sized and properly designed for the application that you are looking for, rather than trying to push a piece of potentially dangerous equipment beyond its rated operating conditions. You can do what you want but I am just trying to inform you of the potential risks and the need for a proper heating load calculation and research in order to determine whether or not you are about to blow something up. It's more for safety reasons than anything and I wouldn't be able to sleep tonight without informing you of the risks.

Hope this helps, and if you need any help performing a cooling load calculation as well as sizing your garden hose and PVC heat exchangers...I have taken a few courses on HVAC/R, thermodynamics, fluid dynamics, and practical heat tranfer.

peace,
agmotes165