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I am wondering if any of you guys know what oil would be best suited for a heat exchange system , I have talked about biodegradeable antifreeze and mineral oil or vegetable oil.

I would like to know if anyone here has any experience in this field dealing with viscosity , expansion , flow , etc.

I would like my unit to have the safest fluid to use as a catalist for the heat transfer as I can find.

any sudgestions.

note: the ground water is normaly 49 degrees F at 35 ft depth.

the ground surface temp is at 8 inch below surface level 50 degrees.

I am using 4 loops of 1/8 inch (ID)polystyrene tube for the circulation of fluids into the cooling coils located at the 35 ft depth.

a total of 100 ft for each of the four loops will be used , leaving 65 ft of coiled tubing per loop immersed in the cooling ground water.

I am using a 1/2 H.P. 150 watt circulation pump to circulate the fluid between the heat exchanger and the cooling tube coils.

the heat exchanger is made of copper tubing.

4 20 ft rolls sandwitched between copper mesh and housed inline
with the already in place air ducting in the attic.

this way the unit can provide cold air using only the 150 watt pump and the already in place heat pump fan and ducting.

that is about the best I can describe the system without going into much more detail , judging from the above which oil or fluid do you think would be the best and safetest one to use.

thanks in advance for any assistance if any.














Quote:
I am using 4 loops of 1/8 inch (ID)polystyrene tube


that should have been 3/8 inch (ID)polystyrene tube.

sorry for those already working on this.

you know the pump will use the same amount of electricity as

1.5 100 watt bulbs !!!

I would say thats a Energy efficient air conditioning system.

we are already experiencing power outages durring the day.

so I might power the pump and fan with a 12 volt car battery connected to a power inverter , just in case the power goes out for awhile.





the circulation pump is a 1/12 H.P not a 1/2 H.P.
big difference there sorry...

Quote:
I am using a 1/2 H.P. 150 watt circulation pump


BTW: if anyone is following this.

I inserted a single loop into the 2" well casing and had difficulty with the loop kinking , so I pressurized the line with 80 psi air and re-inserted the loop into the casing.

I suppose that the pressure helped to open the kink when the end of the loop reached the bottom of the well casing.

the air flowed through the loop and the air entering into the end of the tube that loops into the well and back out again was apx 100 F because it is comming from an air compressor , the air exiting the other end of the loop was apx 60 F , so the single loop seems to be working well using just air through it.

I would really rather use copper tubes in the well but I dont like the idea of having metal tubes in my well.

next week I will try a test run of mineral oil through the single loop to test for the cooling capabilities before continuing.

the 200 ft rolls of the poly tubing cost $38.00 each.


I inserted 2 loops into the well casing today , the results are as follows.

first I had difficulty inserting the tubes and I found out that the well basin is not quite as large as I thought it was.

I was only able to get apx 2 ft of the tubing past the bottom of the well casing then it struck kaolin ( clay sediment layer ).

I was hopeing that the flexible tubing would coil around inside the basin and that I could get at least 100 ft of coiled tubing in the basin.

but I couldnt. so I tried to see if the pump would circulate the mineral oil at a useable velocity , it did and actually too fast.

so lessons learned today have resulted in an even better system
to explore. I found out that what I am building is called a geothermal ground system.

and I found a better way to do it vs using the well water to disperse the heat from the heat exchanger into.

its called horizontal looping , you just dig several trenches in the yard and line the bottom of the trench with the plastic tubing cover up the trenches then circulate water through the tubes and this will provide cold water to cool your house with.

this is supposed to deliver a 60% energy savings on heating and cooling. not bad for something that is free for a little tubing and some digging.










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