Gravity Fed Glycol Chiller?

[JohnSand]

Has anyone tried it? My craigslist ferm fridge died. I generally plan to buy a chest freezer on sale, and meantime use ambient basement temps, a cooler bag and ice. But I wonder if I can use less power in a mini fridge to cool glycol in a coil, keeping the fermenter in a separate cooler, letting the chilled glycol flow down into a coil in the cooler, and rise back as it warms. I realize that the flow would not be very fast, but I don't think it needs to be. The sensor would probably need to be in the fridge, but I could test it either way.
I have to believe one of you home engineers has tested this.

 

[iijakii]

letting the chilled glycol flow down into a coil in the cooler, and rise back as it warms.

That's simply not going to happen.

 

[beermanpete]

If both coils are at the same level you will get some convection flow but not very much. Considering that a temperature gradient is required to get convection flow it is not an effective method when close temperature control is required.

 

[JohnSand]

Obviously they would not be at the same level. With a small fridge it would be easy to put it on a counter with the cooler bag below it. The feed line would go from the bottom of the reservoir, the return line to the top. Convection will cause a flow. The question is will that flow be sufficient, and keep temperature in the proper range. I don't require that it remain within one degree, or two. Just within the preferred range for the yeast, say 65-70 for US-05. The line size will matter, I suspect that bigger is better. I have some 1/2 coil around, probably some auto heater hose. If I try it I'll post results.