High Tech (Peltier) Dry Swamp Cooler

[NSMikeD]

My original plan was to build a peltier unit that could keep my ales about 10°F below ambient temperature as my ac would keep my apt 75°- 79°. Space and aesthetics are an bog concern as this would be placed in view of the living space. Lastly, the unit would cool a 3 gal plastic fermentor and 2 2.5 gallon torpedo kegs. A third keg is tapped in my mini DIY kegerator @ a steady 47°. Note: I naturally carbonate and condition in the kegs.

I decided to build a 2'x2'2' insulated cube with a dual peltier 10A unit. Here is what I used

6 2'x2' x 1/2" Medium Density Fiberboard
6 2'x2' x 1" Owens Corning R-10 Foamular

SODIAL(R) Thermoelectric Peltier Refrigeration Cooling System Kit Cooler Double Fan

WILLHI WH1436A Temperature Controller

AC Infinity AXIAL 1225, Muffin Cooling Fan

P.I. Auto Store 110-120V AC to 12V DC Power Inverter / Adapter / Converter 10 amp

The final box (to be painted to match decor)



Cooing side of peltier



Insulated interior with a circulation fan



Initial temperature at set up



2 x 2.5gal torpedo kegs and 3 gal plastic fermentor
1 Ice Blanket (around Krolsch) and small plastic bucket holding 2 small frozen water bottles and one small ice pack


this afternoon temp



So Far:
I don't think the peltier unit will be powerful enough to do the job by itself.

However, while I was planning this project, I needed to pick up a few "ice blankets) for my kroslch. These have turnout out to be extremely effective as they wrap around the kegs or fermentor. So much so, I expect these to be the primary temperature control.

I have 4 ice blankets, 2 ice packs and 4 small water bottles. Before the build I was using these in 12 hour shifts to keep my lrosch cool. This is over kill for yet cooler. When I loaded the cooler yesterday, temperature dropped to 54° in a mater of minutes. I removed once ice blanket. This morning temp was 63°. I swapped out new ice and it's been holding at 60° for the past 12 hours.


The temperature controller is set for a range of 65° - 69° but hasn't needed to be turned on.


Conclusion:

I will be fine tuning my use of ice, but the early observations leave me to believe that ice will serve as primary cooling source a few seconds of daily attention. This can easily fit in my morning and evening routines.

The peltier will serve as a supplement/back up. At some point, i'll see how long I can go without changing the ice packs to test the limits of the pelter.

I am disappointed with the pelter device. While it's hooked up to a 10 amp device, I had difficulty getting both units to cool. Initially the left side was defective (no hot or cold side), so I received a partial refund and used that to replace the defective unit. The new pelter does have hot and cold sides but lags behind the other until. This may be due to using a 10A power source. I don't want to add more load just yet.

I may shift things around to partition a section with formular for lagering, wrapping a primary and then the keg in an ice blanket.



Total cost was about $180.

 

[NSMikeD]

It's been 24+ hours since I last changed the ice. The temperature rose to 66° by 8am kicking on the peltier units.

The units are a bust as over an hour the temp rose another 2 degrees. I think there are a few reasons for this which I can do modifications to address,

1. The hot side heat sink is exposed to the cooler box. I'll add insulation so no heat from that heat sink makes it way into the unit or near the cool side heat sink.

2. Not enough thermal paste on the replacement peltier (when I swap the defective unit, I scraped and reused the paste. It's does work but no where near the efficiency of the other unit.

3. Cool side heat sink and fans are too small. I'll swap out the cool side heat sink and fan with identical units used on the hot side. This should increase the air flow and exposure to the cool side heat sinks.

Meanwhile I changed the ice and within minutes the temp dropped 13° to 55°.

Ice is clearly effective at temperature control. I'll need to cut back on how much I use and swap it out twice a day to minimize swings. This will be more important when I brew my next batch and need to avoid cold temps during the initial fermentation.

I'll report back after doing the mods to the peltier to see if it can enhance temperature stability and lessen the ice requirements

 

[NSMikeD]

The modifications were a bust. I let the peltier run overnight without any ice - woke uo this morning 68° which is ok, but my apartment was 66. lol

Going to order a new unit, make sure it works and then install. Ice will be my main temperature control with the peltier to have an upper limit.

 

[NSMikeD]

Got the replacement yesterday and much better results. The box was at 70° when I got home, about the same as the room. Took five minutes to swap out the units and immediately the temp began to drop. I went to bed it was 65.5° and running (I think the turn off is set for <65°. When I woke up it was 65.1° and running. I do not know if it shut off during the night, but I was pleased. This certainly is within the range for ales.

Added ice this morning and left the house. It's still at 65.1° but off. I think it's programmed to turn on at 68°

Granted it's cold outside and we are far from the dog days of summer. but I am very happy that the new pelter unit is cooling. There was condensation on the unit this morning.

Next steps is to shore up the insulation to perform like a good cooler, and tweak the temperature controller. I don't mind using some ice packs to assist

At this point, I am confident this will keep my ales cool when the heat arrives*and I set my ac in for the mid 70's

 

[BrunDog]

If you search this forum you will find many who went down the TEC (thermo-electric) road, all with limited results. I myself played with them conceptually... here is what I learned:

1. For the average size box to handle a big fermenter or a couple small ones, you would need 2x 20A+ TECs. That's a lot of juice.
2. Since these generate 3x+ the amount of heat they pump, you need effective transfer, and regular extruded convective heat sinks are inadequate. You would need liquid heat removal, or ideally liquid on both sides.
3. The box needs to be VERY efficient in preventing heat transfer across it. Think foil lining + lots or R factor. This makes for a big box.
3. By the time you add up the hardware needed (TECs, power supplies, pumps, radiators, box material, insulation, hardware, etc.), it is hard to justify the cost. For example, I purchased a perfect ~22cu ft. vertical freezer off craigslist for $150. Tough to beat for the perfect fermenter. I can ferment 4 carboys at a time... not to mention I have a backup fridge or freezer if needed when I am not fermenting.

 

[NSMikeD]

solid points

a fridge would be my fist choice, but I don't have the space for another fridge and aesthetics are part of the equation.

I am delighted that it's been holding temp in the low 60's. More than expected,

My big concern is to keep temp in ale range during summer when my ac runs in the mid to upper 70s.

Admittedly, this has serious limitations, but it will achieve my needs as a small batch brewer needing an alternative solution.

Next step is to complete the insulation and reprogram my comptroller (it's too cold believe it or not).