Closed Loop Wort Cooling System

[ed007]

I just completed and did a trial run of my recirculating wort chilling system and it works like a charm. So, what did I do?
I previously used a plate heat exchanger to instantaneously cool boiling wort by running city water via garden hose connections to my heat exchanger. This, however, wasted a lot of water down the drain. I needed to run the water at full blast, probably around 10 gpm for at least 20 minutes to cool my 5 gallon batch to 65 F for yeast pitching. That is 200 gallons of water for one batch. Well, where I live, water has gotten quite expensive lately, and I was able to get a Neslab FTC-350 Through Flow Cooler for free, so I figured I will make a wort cooling system by recirculating and cooling 5 gallons of water instead of dumping 200 gallons down the drain for each batch.
Neslab FTC-350 is really just a lab sized miniature refrigerator that requires a pump to work. I got a 10 gpm pond pump on Amazon, and connected it inside my water tank to pump out the water. The water tank is temporarily my 10-gallon mash tun, as I am currently doing extract batches because of time constraints (small kids).
The system recirculates the water by pumping out from the tank to the little refrigerated cooler, from the cooler to the plate chiller and back to the tank. The other side of the plate chiller is off course boiling wort.
One more thing that I added is the temperature controller that measures temperature inside the tank and turns the refrigerated cooler compressor on and off based on the set point while continuously keeping the pump running. This prevents freezing over of chilled water.
So, the system works great. I adjust the wort flow via manual valves on the boil kettle and the heat exchanger and the water flow via an adjustment knob on the pump. This keeps recirculating the cold water while cooling wort to optimal pitching temperature. No more wasting water for my beer.

 

[umax]

Can you explain what kind of chiller this NESLAB FTC-350 is? Does it use glycol inside to cool water that enters it? Is it capable to use it through whole wort cooling, meaning you start with boiling wort and finishing with pitching temps all in a closed loop system? How long does it take to cool 5 Gal?

 

[Bobby_M]

That chiller is nearly doing nothing to help. To put it in perspective, if the unit were doing all the cooling, it would take 4 hours to drop 5 gallons of wort by 165F. Once you start running wort through the plate chiller, the water bath is going to heat up extremely fast and will rise above that unit's rated temperature.

 

[k-moe]

That chiller is nearly doing nothing to help. To put it in perspective, if the unit were doing all the cooling, it would take 4 hours to drop 5 gallons of wort by 165F. Once you start running wort through the plate chiller, the water bath is going to heat up extremely fast and will rise above that unit's rated temperature.

The chiller he is using can rapidly cool incoming liquids down to -10C. I think it'll manage keep the recirculating water cold enough to drop the wort temp.

 

[Willy_Liverdye]

My simple chiller. I drilled a 7/16" hole into the elbow of 1/2" x 1/2" fittings put in a rubber grommet for the 3/8" copper wort tube and run 50% glycol at 10 deg through the outside hose. It comes out ready for yeast

 

[ClaudiusB]

The chiller he is using can rapidly cool incoming liquids down to -10C. I think it'll manage keep the recirculating water cold enough to drop the wort temp.

Define rapidly cooling if the unit only has 450 Watts cooling capacity @20°C fluid temperature.

 

[umax]

Define rapidly cooling if the unit only has 450 Watts cooling capacity @20°C fluid temperature.

We must be missing something here. He said he had to put temperature controller to avoid freezing the water in his closed loop, so the chiller is obviously cooling very rapidly?

 

[Bobby_M]

The unit is using air cooling of a heat exchanger (probably a copper coil with fins brazed on). As Claudius wrote, it's only rated at 450 watts of cooling. I know that's not a number most people understand how to think about but it's equal to 1500 btu of cooling per hour. You can quantify that in a few ways but if you think of it in terms of 5 gallons, that's 40 pounds of liquid. It takes 40 btu to drop that 1 degree F. 1500 / 40 = 37.5 degrees per hour.

For comparison, even the smallest of window AC units run 5000-6000 btu. That little unit would work just fine for fermentation control on a couple jacketed or coil cooled fermenters but not even close for wort chilling.

Sure, the unit is capable of dropping water down to cold temperatures given enough time but that's only until the wort starts entering the chiller. At best he can put a large amount of glycol in an insulated tank and recirulate it through the chiller to get it down to 20F and THEN start heat exchanging with the wort but it will take a LOT of gylocol reserves and you wouldn't want to dump the hot glycol back into the same tank. Ice will do much more work than cold glycol.

 

[Bobby_M]

The chiller he is using can rapidly cool incoming liquids down to -10C. I think it'll manage keep the recirculating water cold enough to drop the wort temp.

All you need to do is very basic math to figure out that this is completely untrue.

 

[ClaudiusB]

We must be missing something here. He said he had to put temperature controller to avoid freezing the water in his closed loop, so the chiller is obviously cooling very rapidly?

Bobby gave us all the answers.
To cool 5 gallons from 212° F to 68°F for example takes 6000 BTU/hr or 1758W, or 4 hours to do the job, unfortunately his cooler is rated at 450 W and can't do better.

 

[umax]

The unit is using air cooling of a heat exchanger (probably a copper coil with fins brazed on). As Claudius wrote, it's only rated at 450 watts of cooling. I know that's not a number most people understand how to think about but it's equal to 1500 btu of cooling per hour. You can quantify that in a few ways but if you think of it in terms of 5 gallons, that's 40 pounds of liquid. It takes 40 btu to drop that 1 degree F. 1500 / 40 = 37.5 degrees per hour.

For comparison, even the smallest of window AC units run 5000-6000 btu. That little unit would work just fine for fermentation control on a couple jacketed or coil cooled fermenters but not even close for wort chilling.

Sure, the unit is capable of dropping water down to cold temperatures given enough time but that's only until the wort starts entering the chiller. At best he can put a large amount of glycol in an insulated tank and recirulate it through the chiller to get it down to 20F and THEN start heat exchanging with the wort but it will take a LOT of gylocol reserves and you wouldn't want to dump the hot glycol back into the same tank. Ice will do much more work than cold glycol.

Thank you for detailed explanation. It makes much more sense now.

 

[andrewmaixner]

My simple chiller. I drilled a 7/16" hole into the elbow of 1/2" x 1/2" fittings put in a rubber grommet for the 3/8" copper wort tube and run 50% glycol at 10 deg through the outside hose. It comes out ready for yeast

That appears to be done with all solderless fittings -- do you have links to the parts, as not knowing how to solder is the reason many people don't just make their own?

 

[k-moe]

At best he can put a large amount of glycol in an insulated tank and recirulate it through the chiller to get it down to 20F and THEN start heat exchanging with the wort but it will take a LOT of gylocol reserves and you wouldn't want to dump the hot glycol back into the same tank.

My cusory look at his setup led me to believe that was exactly what he was doing.

 

[Bobby_M]

My cusory look at his setup led me to believe that was exactly what he was doing.

I wasn't so sure based on the fact that the wort chiller was in the loop with the chiller machine and only about 5 gallons of water in the tank. In a completely closed loop, it would take 20 gallons of water @33F and slightly less with glycol under 30F.

 

[ClaudiusB]

I wasn't so sure based on the fact that the wort chiller was in the loop with the chiller machine and only about 5 gallons of water in the tank. In a completely closed loop, it would take 20 gallons of water @33F and slightly less with glycol under 30F.

Unfortunately the cooling capacity for that chiller is only 180 Watts at 0°C (32°F) per specs.
My glycol chiller has a 30 gallon tank and I still use a pre chiller with city water to do the job and keep the temp rise around 10°F in the reservoir.

 

[mattd2]

Bobby gave us all the answers.
To cool 5 gallons from 212° F to 68°F for example takes 6000 BTU/hr or 1758W, or 4 hours to do the job, unfortunately his cooler is rated at 450 W and can't do better.

I think you may confuse some people with the way you said that:
Cooling 5 gallons from 212° F to 68°F in one hour takes 6000 BTU/hr or 1758W. If you wanted to do it with a 450W coller it would take approx. 4 hours.

 

[Willy_Liverdye]

That appears to be done with all solderless fittings -- do you have links to the parts, as not knowing how to solder is the reason many people don't just make their own?

No solder needed. Grommet must be for 1/8" thick material or it will drive you to drinking trying to get it set in your hole

 

[ed007]

The chiller he is using can rapidly cool incoming liquids down to -10C. I think it'll manage keep the recirculating water cold enough to drop the wort temp.

The idea is to pre-cool the system water (10 gallons) down from room ambient to just above freezing and keep it there until you are ready to start cooling the wort. You could even go below freezing if you used glycol water mixture. The controller is just there to maintain the recirculating water temperature until you start cooling the wort. The little lab chiller is not sized to maintain the cooling rate while the boiling wort is running through the heat exchanger.
Once you start running the wort through the external heat exchanger, the cooling water temperature will slowly rise while being recirculated through the system and back to the supply tank. I have been able to practically cool 5 gallons of wort from boiling to 72 F in about 25 minutes with a 10 gallon supply of chilled water at 32F.