AC to glycol chiller question

[Nimbus3000]

For those of you who have converted an AC into a chiller has anyone tried placing the condenser unit in a smaller container and then circulating the glycol from a larger container around the coils then back to the larger container. Thanks

 

[Nimbus3000]

Also, if anyone has a suggestion for bypassing the thermostat it would be appreciated. The one white wire (power in) goes to the fan selector and the other leg goes to the capacitor. The yellow wire goes from the fan switch to the thermostat and the yellow/black wire goes from the thermostat to the compressor. All of the other wires go to the fan motor for speed control. Thanks

 

[Bobby_M]

For those of you who have converted an AC into a chiller has anyone tried placing the condenser unit in a smaller container and then circulating the glycol from a larger container around the coils then back to the larger container. Thanks

Not that this wouldn't work, but what benefit do you think it would provide?

 

[Nimbus3000]

I was only looking at stacking the ac above the tank to minimize the footprint while increasing my glycol volume. Bypassing the thermostat is my first chore before anything else. Thanks

 

[Bobby_M]

You may be able to just drop the coil down into a cooler below the unit directly if there's enough slack in the lines. Every AC is a little different in that regard.

How you bypass the controls depends on what external controller you're looking to use. Most people use an STC1000.

 

[sbro]

Not an electrician, but if you join the 2 spades on the temp controller, that would bypass the temp so it would not shut off the unit when it senses surrounding air too cool.

That looks like these 2 connectors, remove them and connect them together (the yellow, yellow-black, and black)

Then just set the unit in automatic fan and your inkbird or other controller would be in charge of turning things on and off.

 

[Jag75]

This is my set up. Bobby has a good idea if the lines are long enough, you could set the ac unit on top of the cooler . If they're not long enough , could you invert the ac unit to sit on top , but point up towards the ceiling?

 

[Nimbus3000]

Thanks. Jumping the wires was my first thought. Interesting thing is that the yellow wire from the fan switch looks like #12 while the yellow/black wire from the thermostat looks like a #10.

 

[Jag75]

Don't know if this will help , but ...

 

[Nimbus3000]

Removed the wires from the thermostat and put a jumper between them. All of the smoke stayed inside the insulation when power was applied. Cooler and stand next. Thanks to all.

 

[sbro]

Looking closer, you can avoid the jumper by removing the yellow wire from terminal 2 on the switch and from the thermostat, then remove the other terminal from the thermostat (black-yellow and black) then connect it directly to switch terminal 2 where the yellow was. The advantage is eliminating one jumper connection if the wires are long enough to do that.

 

[Nimbus3000]

Thanks to all. Initial testing with straight water works. Repainted housing in hammered copper. Still need to build rolling cart.

 

[Nimbus3000]

Another question for you all. What did you use to seal up the notch where the pipes enter the cooler (or leave the notch open)? I can't find a product that is compatible with the propylene glycol.

 

[Jag75]

I used spray foam .

 

[Bobby_M]

Hopefully the slots are not under liquid level because it's very hard to get anything to stick to the cooler liner

 

[Nimbus3000]

Nope. But the top 1" or so of the coil is exposed. Any more bending and the compressor tubing will break.

 

[Nimbus3000]

Any suggestions for where to purchase inhibited glycol?

 

[Jag75]

Any suggestions for where to purchase inhibited glycol?

I purchased through Amazon. If I remember right, it's probably 30$ a gallon

 

[Jag75]

Shoot look at this deal .

BulkBliss Food Grade Propylene Glycol for Soap, Oils, Cosmetics and Lotions - 1 Gallon (128oz) https://a.co/d/4NvDI1B

 

[superiorsat]

https://www.amazon.com/Inhibited-Pr...-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
https://rapidswholesale.com/glycol-solution-5-gallon.html
https://cannonwater.com/douglas-htf-inhibited-propylene-glycol/
The last place you can buy it by the gallon.

 

[Nimbus3000]

I have the system up and running with a dual tank setup where one tank has the glycol mix and air conditioner coils and the other tank uses just water that will be used to cool the fermenters. The liquid from both tanks continuesly recirculates through a plate heat exchanger. I have found that the plain water tank has very stable temperatures. Even when the mix tank changes by 3 degrees the plain water tank holds within a degree or less. Now my question, is it better to run the air conditioner for a shorter time more frequently or longer time less frequently to extend the life of the air conditioner? Thanks

 

[sbro]

My feeling is longer cycles, less frequently would be better for the compressor and associated components. Less frequent should be more efficient but I doubt it wold be enough to notice much savings.

 

[Nimbus3000]

New to setting up a chiller so have some more questions. I have a 620 GPH pond pump pushing water (this is a test) continuously through 1/2" insulated pex pipe for about ten feet before the water returns to the tank. I have checked the flow and found that the rate is at 10 GPM at 65 degrees and drops to 5 GPM at 38 degrees. Anyone have an idea what is going on? Fluid dynamics is not the type of engineering that I went to school for. Thanks

 

[sbro]

That doesn't look right. The density difference of plain water from 65 to 38 is very small so I would not expect much change in the flow rate. The viscosity also did not change much. You would see more of a viscosity change in a glycol mix.
Does the pump performance change at the different temperatures? Perhaps bearing drag? Typically not but possible.

 

[Nimbus3000]

That is why it confused me. The other option may be that the meter is getting flaky since the low temperature for the meter is 38 degrees and it is a cheap flow meter. Thanks

 

[sbro]

Put the end into a gallon jug and time how long to fill at each temp. The times should be close as long as the pex remains at the same height (same head pressure).

 

[Nimbus3000]

Question for folks using a 3/8" coil. What kind of flow rate do you normally get through the coil? I am getting less than 2 GPM using a pond pump at about 3 psi. Is this a normal flow rate. I have not used tubing this small in the past. Thanks