# Geothermal Refrigerator



## zimmy (Aug 17, 2012)

Every year a group of us get together for a pot luck and apple pressing. I usually start collecting my apples in late September and October and we press apples in late October or early November. The problem I have is trying to keep the apples from going bad until I can press them. 

A root cellar would be nice but I don't have one so I thought I would just try to make a cold box using what I have. My original plan was to just dig a deep hole, dump in some sand, and install the large radiator in the sand at the bottom of the hole, A pump would flow propylene glycol through the radiator and into the cool box using one or two solar panels to run the pump.

Now the question I have is should I bury the the tanks in the ground and use them as a thermal mass to collect the cold from the ground to be put into the box. Should I bury the radiator in the ground to collect the cold from the ground and put the cold into the above ground tanks and the box would take the cold from the tanks. Or what about install the radiator above ground in the open air and take the cold from the night air. Any thoughts on all of this.


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## bacpacker (Jul 15, 2011)

No answers for you. but I will be following the thread for discussion.


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## tmttactical (Nov 23, 2015)

From a purely maintenance stand point, I would leave everything about ground. Tanks and coils should be in a secondary containment, to avoid possible ground contamination from leaks. Air flow / excessive freezing can be controlled using wind proof thermal covers if needed. It is much easier and less labor intensive to repair items above ground.  It is also much easier to spot a (small) leak before it become a major leak. Just my 2 cents.


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## zimmy (Aug 17, 2012)

tmttactical said:


> From a purely maintenance stand point, I would leave everything about ground. Tanks and coils should be in a secondary containment, to avoid possible ground contamination from leaks. Air flow / excessive freezing can be controlled using wind proof thermal covers if needed. It is much easier and less labor intensive to repair items above ground.  It is also much easier to spot a (small) leak before it become a major leak. Just my 2 cents.[/QUOTE
> 
> If the tanks aren't in the ground they wouldn't collect any cold from the soil. The radiator could be put in the ground to collect the cold to go to the above ground tanks but now the tanks need heavy insulation. For the most part propylene glycol is no toxic and I need something to prevent freezing of the evaporator coil in the insulated box.


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## hiwall (Jun 15, 2012)

tmttactical Makes a good case for above ground. Seems a shame not to use nature's always cool ground though.
Advantages to the below ground is less chance of freezing, constant temps whether day or night and even pretty constant winter or summer, and being able to use it for something else in the warm summer months (even just to store your beer).


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## Tirediron (Jul 12, 2010)

the night sky will absorb a great deal of heat if there is no cloud cover, where as the soil temperature unless subjected to freezing weather will only be about 56 degrees F. I would also think that an aluminum tank would transfer radiant heat better than a air flow type radiator,


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## zimmy (Aug 17, 2012)

Tirediron said:


> the night sky will absorb a great deal of heat if there is no cloud cover, where as the soil temperature unless subjected to freezing weather will only be about 56 degrees F. I would also think that an aluminum tank would transfer radiant heat better than a air flow type radiator,


The tanks are plastic with pex tubing packed inside in a spiral. One of my ideas was to bury the tanks in the ground but not cover them completely to allow cover removal for maintenance. The pex tubing would have a glycol/water mix that would be pumped through the evaporator coil in the insulated box using a dc pump, battery, solar charge controller, and pv panel. The inside of the insulated box wold have a temperature controller to turn the pump on at a preset value. The glycol in the the pex and evaporator coil will never freeze preventing damage.

The radiator is 4'x8', copper pipe, aluminum fins, where can I use this in my system.


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## hiwall (Jun 15, 2012)

> The tanks are plastic with pex tubing packed inside in a spiral.


You would be using air for heat/cold transfer in a dead air space which is very inefficient, better to have those coiled tubes immersed in water in those tanks.


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## Caribou (Aug 18, 2012)

Water is heavier than air so it holds more heat/cold. Water transfers heat 25 times faster than air. One half inch Pex tubing can only run about 500' in a single line/loop before restrictions make pumping problematic. Multiple loops is the answer if additional radiation is required.


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## phideaux (Nov 7, 2015)

Just something I've seen in my lifetime.

Back in the early 70s I used to go to upper central Canada , to fish and hunt.
An old guy that lived there (200 miles from nearest person) year round had a refrigerator that he stored our fish in, until we were ready to leave. 
Worked great.

He had a shack built over a 6 ft dia hole in the ground to keep the weather and sun out , not sure how deep , but it was at least 6 ft deep.

It was filled with sawdust , and in the winter he cut blocks of ice 12" square from the lakes, every year he put a couple blocks down into the sawdust, and our fish was in ziplock bags and pushed down into the sawdust, ....I was amazed how he kept things in there year round.

He said there were blocks of ice, in there, been there, 25 years. I dunno, 

Just know it worked. I pushed my hand down into it about a foot or so, and it would get uncomfortably cold in a few minutes.


Jim


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## Caribou (Aug 18, 2012)

Ice houses uses to be the thing. In the winter people would go out and harvest ice, usually off a lake. These ice blocks would be hauled back to the icehouse where they would be separated with layers of sawdust. 

Somewhere I have a picture of the truck my grandfather used when he delivered ice. If you ever heard a refrigerator referred to as an icebox it is because people used to have a refer sized box in their home and the iceman would deliver this block of ice that was placed in an upper chamber.

Friends of mine bought an old house. They had a walk-in chill room. In the day it was filled with ice and food. They ripped out the wall panels to reveal about 18" of sawdust that had been used for insulation. It was turned into another bedroom.


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## zimmy (Aug 17, 2012)

hiwall said:


> You would be using air for heat/cold transfer in a dead air space which is very inefficient, better to have those coiled tubes immersed in water in those tanks.[/QUOTE
> 
> Perhaps I haven't explained myself very well. The two tanks could be buried in the ground, the two tanks will have water in them, the pex tubing will be in the tanks submerged in water, glycol will flow through the pex tubing, into the evaporator coil in the insulated box, making the box cool inside. Again, what part will the large radiator play in this hair brain idea?


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## zimmy (Aug 17, 2012)

*Ice box*



Caribou said:


> Ice houses uses to be the thing. In the winter people would go out and harvest ice, usually off a lake. These ice blocks would be hauled back to the icehouse where they would be separated with layers of sawdust.
> 
> Somewhere I have a picture of the truck my grandfather used when he delivered ice. If you ever heard a refrigerator referred to as an icebox it is because people used to have a refer sized box in their home and the iceman would deliver this block of ice that was placed in an upper chamber.
> 
> Friends of mine bought an old house. They had a walk-in chill room. In the day it was filled with ice and food. They ripped out the wall panels to reveal about 18" of sawdust that had been used for insulation. It was turned into another bedroom.


Yes the Amish in this area have a outside ice box and they cut ice from the pond they have on their property and put it in the ice house. The pond didn't freeze over this year so they will have to buy ice.


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## zimmy (Aug 17, 2012)

Caribou said:


> Water is heavier than air so it holds more heat/cold. Water transfers heat 25 times faster than air. One half inch Pex tubing can only run about 500' in a single line/loop before restrictions make pumping problematic. Multiple loops is the answer if additional radiation is required.


Actually who ever put the pex tubing in the tanks knew what they were doing because the pex is not all in series but several series strings are in parallel. All the series strings terminate into a manifold. Well thought out.


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## Tirediron (Jul 12, 2010)

If you built a tank that the radiator could sit flat in and filled it with some of your glycol mix, with some kind of coloring to make the mixture black, cover the tank with something clear, and use that as your night sky heat remover.


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## Caribou (Aug 18, 2012)

zimmy said:


> hiwall said:
> 
> 
> > You would be using air for heat/cold transfer in a dead air space which is very inefficient, better to have those coiled tubes immersed in water in those tanks.[/QUOTE
> ...


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## zimmy (Aug 17, 2012)

*Geothermal refigerator*



Caribou said:


> zimmy said:
> 
> 
> > You could attach the radiator horizontally near the ceiling and let the cool air drop down on your food or you could mount it vertically and put a fan behind it to circulate the air. You need a heat exchanger in the ground, your tanks would be excellent for that. You also need a heat exchanger in the box. Your radiator would do well there. Basically you are using the radiator as a unit heater, or in this case cooler.
> ...


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## zimmy (Aug 17, 2012)

Tirediron said:


> If you built a tank that the radiator could sit flat in and filled it with some of your glycol mix, with some kind of coloring to make the mixture black, cover the tank with something clear, and use that as your night sky heat remover.


I would think it would be best to expose the radiator to the open night time cool air. The radiator would have to have its own control valves and pump to take it out of the in ground tank cooling loop during the daylight hours and also be shaded from the sun. Sounds very complex.


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## zimmy (Aug 17, 2012)

At this point it sounds like the radiator has little to no application in the project. Should be worth some money at the scrap yard.


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## Caribou (Aug 18, 2012)

zimmy said:


> At this point it sounds like the radiator has little to no application in the project. Should be worth some money at the scrap yard.


I would say you are right.

I don't know how cold it is in your area but I expect that the ground is more of a warming influence than a cooling one. If you set up the large radiators in a way that you can pump the cold into your storage system in the winter and then into the chill box in the summer that might work.

My last house was built above permafrost. Your system would have worked well there. Your ground is much warmer and will only have the ability to cool to the ground temperature.

Pump heat from the chill box to the ground in the summer and pump cold from the air into the ground in the winter. This MIGHT help keep your chill box cooler for a longer period in the summer.

Let us know what you come up with.


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