Peltier cooler on a conical. Experience?

[bcrawfo2]

Stout tanks sells a kit that has an aluminum heat sink, two peltier chips, fins and fans.
Anyone used this or something similar? I would love to use something this clean and simple to help maintain ale fermentation temps in my 70 degree basement.
The ss brewtech solution of a heat exchanger sitting in the wort in the conical seems counterintuitive. You spend so much time eliminating the nooks and crannies in the fermenter and then put something in there with lots of them

 

[tribble222]

I am also considering this. I wonder if 2 blocks would be enough for lagers or if I'd need 4? Which peltier to buy on eBay? And also important, what electric bill can I expect? I keep hearing peltiers are very inefficient...

 

[tribble222]

Alright, I ordered a 7 gallon Stout along with 2 of their peltier kits. Now to source the chips from ebay.

 

[Bensiff]

This will be interesting to see how it works out. I also wonder if you could flip the peltiers so you get both heating and cooling. I will say the kits from stout are horrendously expensive. I have a friend who works at a cnc shop her parents own and she said she would be happy to fab up some blocks for me if I ever want to try this.

 

[doug293cz]

This will be interesting to see how it works out. I also wonder if you could flip the peltiers so you get both heating and cooling. I will say the kits from stout are horrendously expensive. I have a friend who works at a cnc shop her parents own and she said she would be happy to fab up some blocks for me if I ever want to try this.

Can't you just reverse the polarity on Peltiers to move heat in the other direction?

Brew on

 

[Bensiff]

That sounds right. Haven't played with them yet so lots to learn if I ever do.

 

[tribble222]

I finally got everything put together. I had to dremel off the feet of the heatsink because they were getting in the way so my peltier chips weren't making direct contact with the heatsinks. Now that I dremeled them they are making direct contact.

I filled my conical with 6 gallons of 114F water and turned it on. I've been taking occasional measurements and it's still not quite down to ambient yet. I didn't really mean to start with water so hot but I was using my hot water tap so it ended up being that way.

Here are the measurements I've taken so far:

114f @ 1:24pm
103 @ 149
91 @ 2:32
82 @ 3:22
79 @ 3:48
72 @ 5
69 @ 6:29

Ambient is 66. I've been trying to calculate if it's cooling faster than it would without any peltiers but I can't figure out the calculation to any degree of certainty.

The aluminum blocks are definitely colder to the touch so the peltiers are doing something.

 

[tribble222]

67 @ 7:10
64 @ 11:13

I plugged in my kill-a-watt and it's pulling 350 watts from the wall, which is a little odd since each peltier is supposed to be rated to 130 watts and I have 4, which would make me expect to see 520 watts being pulled from the wall...not including whatever wattage the fans take up from spinning as well.

 

[tribble222]

62 @ 7:50am

It seems to have maxed out at 62, which is disappointing. I looked at the specs of the peltiers I bought and they are 90W @ 12V so pulling 350 watts from the wall isn't that far off.

Upon reading that running peltiers even just a few volts too low really impacts their efficiency, I hooked up my voltmeter and discovered they are only pulling 10.5v from my power supply. They are rated up to 15.4v max so my next task is to either modify my power supply or find another that can consistently output 15v without dropping under load.

 

[mliptack]

Can't you just reverse the polarity on Peltiers to move heat in the other direction?

Brew on

Yep. Reversed polarity will reverse the hot/cold sides.

Tribble - what size peltiers did you use?

Did you use any type of thermal paste between the peltier and the heatsink or conical?

What is the ambient temp in the room? (this is a big constraint with peltier coolers).

Did you insulate your conical?

 

[tribble222]

Yep. Reversed polarity will reverse the hot/cold sides.

Tribble - what size peltiers did you use?

Did you use any type of thermal paste between the peltier and the heatsink or conical?

What is the ambient temp in the room? (this is a big constraint with peltier coolers).

Did you insulate your conical?

The peltiers are 40mm square. Here are the ones I bought http://www.ebay.com/itm/270739268599?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

I used thermal paste between the peltier and heatsink and between the peltier and aluminum block. I did not use any thermal paste between the aluminum block and the conical.

The conical is insulated on sides and top with reflective bubble wrap.

Ambient temp is 65F

I read somewhere that hooking up a load to the 5v rail on an atx power supply will help get more voltage out of the 12v rail, so I got a power resistor and hooked it up. It gave me an extra .5v so I can run at 11v now instead of 10.5. Unfortunately, it hasn't seemed to increase the effectiveness of the peltiers.

 

[mliptack]

I think I have some of those exact same TECs.

What is the supply amperage?

Do you have a way to measure the TEC's cold side or heatsink?

Try taking it off of the conical. CA is humid enough, it should frost over pretty quickly, or if you spray it with water it should freeze.

 

[MrNatural]

I read somewhere that hooking up a load to the 5v rail on an atx power supply will help get more voltage out of the 12v rail, so I got a power resistor and hooked it up. It gave me an extra .5v so I can run at 11v now instead of 10.5. Unfortunately, it hasn't seemed to increase the effectiveness of the peltiers.

Check craigslist for ham radio power supply. They put out 13.5 VDC. This one is 35A for $80. Keep looking and you can find 10A-15A for $20 or so.
http://sfbay.craigslist.org/pen/ele/4850530682.html

 

[tribble222]

I think I have some of those exact same TECs.

What is the supply amperage?

Do you have a way to measure the TEC's cold side or heatsink?

Try taking it off of the conical. CA is humid enough, it should frost over pretty quickly, or if you spray it with water it should freeze.

My power supply is rated 12v up to 40amps. The peltiers only do 9amps max I believe.

I pulled one pair off of the conical. After running it on its own for 10 minutes, the coldest spot on the aluminum block (directly behind the peltier chip) is 44F. Enough to condense water but not freeze it.

One thing that could be the problem is that the heatsinks supplied by Stout have insufficient surface area to cover the entire peltier chip. The heatsink only covers about 35mm square but the peltier is 40mm square...

Edit: the heatsinks are only getting up to 76F so they aren't having any trouble dissipating the heat.

 

[mliptack]

That definitely could be a part of it. Not sure exactly if not cooling part of the TEC will reduce its overall effectiveness or not - sure seems like it would have an effect.

Do you have any other heatsinks? Or friends who build their own computers or work in IT?

 

[tribble222]

I don't have any other heatsinks to try. I took the chip off the aluminum block and ran it only attached to the heatsink/fan. It got below 32 (as low as my thermometer will measure) and frosted pretty quickly, in 30 seconds I'd say. It's possible I just had a poor connection between the chip and the aluminum. I'll try to squirt more thermalpaste in there and test again.

 

[NeoBrew]

I've been experimenting with peltiers in a different application. (Liquid cooled copper coil around my glass carboy) I've found a few tricks that might be useful for you.

One is that using just the right amount of thermal paste is critical. Too much and it insulates the transfer, too little and you don't get as good of contact. Also, once you get it set, don't let anything move even a fraction. It seems to disturb the bed of thermal paste and hurt efficiency. I would also put paste between the conical and the aluminum block. It's a surface area and increasing the efficiency there will help over all.

I would also say you don't have enough heat sync capacity. One of the limitations of a peltier is that if the hot side stays too hot, the cold side will not get as cold as it could. I am guessing the heat transfer from the hot side to the cold side limits things? I used a peltier set from Adafruit. It has a way over-sized cooling block. http://www.adafruit.com/product/1335 The cooling block is 90mm, much larger than the peltier. It allows me to get the peltier down below freezing with just 12 volts.

The last thing I'd suggest after all that is to put some better insulation on the fermenter. Reflectix provides very little in terms of R-value. It's properties are not very well documented by the company, but you are not really getting much actual insulation at all. Of course, this won't help with your current problem of getting it down to ambient, but it should help any time you are significantly off the ambient temp.

 

[doug293cz]

Can you post some pictures of your configuration showing how the units are mounted on the conical, and details of the heatsink, Peltier, and Al block? You might generate more suggestions from some pics.

Brew on

 

[tribble222]

Ok, here's a link to some pics of the setup:

http://www.evernote.com/l/AIbYwBgqkZBA3YPr3kE-_HlFuPysjTXg1GU/

The aluminum block is getting down to 44F but not more. That's about 20F below ambient. Do you think that's normal?

 

[tribble222]

I reapplied thermal paste and reversed the fans so they blow away from the heatsink instead of into the heatsink and now I'm getting the aluminum block down to 35F.

I'm going to give the other set the same treatment and then try hooking it up to the conical again.

 

[doug293cz]

Ok, here's a link to some pics of the setup:

http://www.evernote.com/l/AIbYwBgqkZBA3YPr3kE-_HlFuPysjTXg1GU/

The aluminum block is getting down to 44F but not more. That's about 20F below ambient. Do you think that's normal?

Ok, the pics are a big help.

I reapplied thermal paste and reversed the fans so they blow away from the heatsink instead of into the heatsink and now I'm getting the aluminum block down to 35F.

I'm going to give the other set the same treatment and then try hooking it up to the conical again.

You should insulate the aluminum blocks on the room side, and do the best you can to keep the airflow from the fans from flowing over the Al blocks. Room air will just warm up the blocks.

Turning the fans around was the right thing to do, as it reduced the air flow over the Al blocks. You are still pulling some ambient air over the Al blocks, but thats way better than blowing heated air from the hot sides of the Peltiers at them.

I'd also suggest a thin Al sheet be placed to block air from coming up thru the bottom of the heatsink fins, and insulation placed between the Al sheet and Al blocks. This will prevent air from flowing over the Al blocks.

If the above is not clear, let me know.

Brew on

 

[tribble222]

Thanks for the suggestions - they make a lot of sense! I will try them out and report back. I also ordered a large .5mm thermal conductive pad to put between the aluminum blocks and the conical.

 

[tribble222]

Re-seating the heatsinks and reversing the fans helped enough to get it down 15 below ambient. I'll experiment more later with better insulation but right now I've got a stout fermenting stable at 67 (ambient 70) and it's working great!

 

[stealthfixr]

trible222, how low have you been able to go with your setup after the tweaks, since the #23 post? What advice would you have for others interested in the same/similar methodology?

This *seems* like a better temp control method than the FTSS recently released, but is much more DIY, trial and error. Too bad no one came out with more of a "Cooler Peltier Kit" with everything needed in one place.

 

[tribble222]

I haven't had time to try and get it lower than 15 below ambient yet. I'm brewing 4 beers quickly in a row for a large party I have coming up. I kegged my stout a couple days ago and now I have an IPA fermenting in there. I don't think the bubblewrap insulation really did much so right now I'm running it without. I have my IPA dialed in at 64 degrees and it's been able to keep it there without working much, even while fermentation is heavily underway. I filled the fermenter at 78F and it cooled it like this, running constantly:

8:39pm - 78F
9:25pm - 72F
11:06pm - 68F

I pitched the yeast at 68, continued to cool to 64, and have been maintaining it at 64 ever since. Ambient is around 70. I know from past experience that under active fermentation, with no temp control, it could get up to 78 in my 70 ambient room.

It doesn't seem to need to run much. I'll plug in my Kill-a-watt tonight and see how much it's running to maintain temps.

 

[tribble222]

Ok, as of 7:19pm, it has used .84 kWh. It uses around 410 watts when running, so that means it ran for 122 minutes over the course of 23 hours, which extrapolates to 127 minutes per day.

My electricity on the third tier (which I sometimes do hit in the winter with electric heat) is 20 cents per kWh so that means it's costing me 16.8 cents per day or $5/mo to run this thing. Not bad!

Of course that's not a massive temperature difference. If I was running it as low as it could go (so, constantly) it would cost $59 per month, worst case scenario.

 

[Bensiff]

So sounds like an economical solution for small adjustments but glycol or a dedicated refrigerator would be better for large temp corrections.

 

[JohnnyBe]

Tribble have you been able to experiment with this any further?

 

[tribble222]

Tribble have you been able to experiment with this any further?

No I haven't really tried anything new yet. The only modification I've made was to install a fan bus so I can turn down the fan speeds. I found I can run them at about 40% of max and still get just as effective cooling. This saves a lot on noise since my conical is currently living at my bar in my dining room. I've been pretty happy with how it's working. I ferment most of my beers in the 60s, which it has been able to maintain quite easily.

I've brewed 8 beers in my peltier cooled conical since I started this thread. I fermented an Oktoberfest last month which I could only get down to 57F (ambient 71F) during active fermentation. After fermentation it was able to drop it to 55F. It's now lagering in my fridge.

The biggest issue I've had is condensation dripping off the aluminum blocks. I bought a giant cutting board with a trough around the edge and placed the conical on the cutting board. The water evaporates faster than the trough fills up so it doesn't ever overflow, even when running constantly as was the case with my Oktoberfest.

The next thing I'll try is blocking the back of the heatsink fins so that the air has to be drawn through the sides and not the back. I expect this should let me drop the temp a bit lower.

Right now my ambient temp is 77F and I have an Ordinary Bitter fermenting on day 3 @ 65F. The conical doesn't seem to need to turn on too much for this one.

 

[mbbransc]

I believe you probably just answered this question since you couldn't get the lager below 55°, but have you been able to cold crash at all since?

thx