# Peltier air conditioning project



## allanschon (Mar 25, 2007)

Well, I've seen this idea tossed around a bit, but I've never seen anyone who claims to have implemented it. Being a sadist, I've decided to give it a go.

I'm new to dart frogs, but I want to make sure that my frogs have the best environment that I can provide. I've just completed my first vivarium, and the first thing I've noticed is that the temps are way too high. My apartment is on the top floor, and faces west, so all afternoon heat builds up. It was 76 degrees outside today, 82 in my apartment, and [email protected] in the viviarium. Unfortunately, the heat sticks around too... As I write this, the outside temp has fallen to 66, and it's still 80 inside. Luckily, I haven't picked up any frogs yet.

I have air conditioning, but I'm cheap, and I'd rather not cool the entire apartment when I'm at work, and I'm only concerned about the 6 cubic feet that make up my exo-terra. So, I've decided to tackle a DIY air conditioner for the frogs.

For those who are unfamiliar with peltier coolers, read Peltier FAQ.

Essentially, I'm going to going to install a peltier cooler in the wall of a watertight enclosure. On the outside of the box, a large heatsink and fan will dissapate the heat, and two ducts and a fan will carry hot air from the terrarium and cool air back. Power will be supplied by a surplus computer power supply I had lying around. Condensation from the cooler will be routed to the terrarium's sump tank.

I've just ordered the heatsinks, fans, and peltier. I'll post pics once the parts come in.


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## Dancing frogs (Feb 20, 2004)

They have been experimented with a little before, but probably not enough.
I started too, but lost interest fairly fast, as I have frog tanks in all but two rooms of my apartment, so AC is probably the cheapest way for me.

Good luck with you're experiment, and please do post results.


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## defaced (May 23, 2005)

Sounds like a cool idea, but can you post a drawing? I'm not seeing this at all.


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## Dancing frogs (Feb 20, 2004)

One of the roadblocks I encountered in my limited experimentation was finding a nice big heatsink for the cold side (for heat collection) that didn't cost an arm and a leg...that and trying to figure out how to best insulate the cold side from the hot side.


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## allanschon (Mar 25, 2007)

I'd be glad to post a diagram. I just have to draw one. 

If you google 'peltier air conditioner' you'll come across sites that detail the peltier + heatsink assembly, which might help you picture what I'm talking about.


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## Haroldo (Mar 14, 2006)

I've familiar with these cooling solutions as I used to do custom waterblocks and phase change systems for computers. Chances are, the power supply you'll need to juice this peltier up is likely to near what a small air conditioner might be pulling. I'd consider figuring out wattage needs before ruling out an entire room. Good luck in your search and project and be sure to post updates...


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## defaced (May 23, 2005)

Power out ~= power in. Most peltiers are in the range of 60 watts. In order to supply that 60 watts from line voltage, his supply would consume about the same power as a 75 watt light bulb (which accounts for losses in the power supply). That's far from what is used by an air conditioner of any size. You're probably thinking that at 12v this thing is going to need 5 amps, which is right, but the supply won't be operating at 12v, but at 120v, so it'll need more like .6 amps.


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## allanschon (Mar 25, 2007)

If I could cool the room, that would be an option, but the viv is in my apartment's main living area. I'd have to cool about 800 square feet of living area, which would cost >$75/month. I think I can build this whole thing for less than $125. At that rate, It'll pay for itself in less than two months.

In order to make sure I bought an appropriate cooler, I used the sizing software from here to estimate the total amount of heat I'd need to dissapate. I figured on about 80W, so my power supply will be pumping out around [email protected] With the losses from the power supply and the small power draw for the fan, I figure total energy usage will be just less than for my lights. 

At first, I'll just leave it turned on all day, but my other project is building a controller for the whole climate system. I'll start another thread on it when I'm closer to starting, but in essence, I'll have my water heater, humidifier, and (hopefully) my AC unit attached to relay circuits which will in turn be controlled by a PIC microcontroller and a temp/humidity sensor.


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## alifer (Oct 24, 2005)

Do you think it would make your project easier by buying a small peltier refrigerator and modifying it with a temp controller and ductwork with a low voltage fan for air circulation? My wife bought a peltier refrigerator/cooler for my son at Target or Walmart so he could keep cold drinks in his room and it works well if the drinks are cold before placing them in the cooler. It's big enough to hold a 6-pack of sodas.

Rick


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## allanschon (Mar 25, 2007)

I considered doing that, but for the following reasons, it probably wouldn't work:
1) the fridges and coolers are insulated, thus don't require as much power to cool. 
2) Most of them enclose less space than the size of my xxxl exo-terra.
3) I have lights pumping heat into the tank; I doubt these coolers would work if you left them sitting in the sun.

As a result of the above factors, I think that the peltier unit in those fridges would be underpowered for this application. On the other hand, they might be appropriate for a smaller tank, such as a 29g. 

In either case, the cost would be the same or higher than the DIY approach.


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## Dancing frogs (Feb 20, 2004)

I didn't download the sizing guide to see what all it entails.
I saw one that included thickness of wall material (tanks offer little insulation) heat input (you're lights), ambient temperature, target temperature, and I think it had a relative humidity input as well, as condensation on you're cold side of the peltier interferes with the ability to remove heat.
In my limited experiments, the 55w peltier I bought didn't drop the temp of a 2 gallon enclosure very much, but then again, I didn't spend a whole lot of time on it. I think the problem there was trying to find a good way to insulate the hot heatsink from the cold one. I didn't have a fan on the cold side either, and I'm sure that would help.


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## alifer (Oct 24, 2005)

allanschon said:


> I considered doing that, but for the following reasons, it probably wouldn't work:
> 1) the fridges and coolers are insulated, thus don't require as much power to cool.
> 2) Most of them enclose less space than the size of my xxxl exo-terra.
> 3) I have lights pumping heat into the tank; I doubt these coolers would work if you left them sitting in the sun.
> ...


I had thought more along the lines of keeping a small peltier fridge running full time behind or below the viv with say a big water bottle or something inside the fridge to act as a cold sink, then when your temp controller decided the temp inside the viv was too high a low voltage fan would kick in circulating warm air from the viv into the fridge and cooler air back to the viv using some flexible air tubes. 

I recently installed a peltier type chiller on my nano-reef tank and it actually works pretty well at pulling down the water temps to below the ambient room temp. Here is the link 
http://www.nanotuners.com/product_info. ... 5e067272b5

Rick


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## Haroldo (Mar 14, 2006)

defaced said:


> Power out ~= power in. Most peltiers are in the range of 60 watts. In order to supply that 60 watts from line voltage, his supply would consume about the same power as a 75 watt light bulb (which accounts for losses in the power supply). That's far from what is used by an air conditioner of any size. You're probably thinking that at 12v this thing is going to need 5 amps, which is right, but the supply won't be operating at 12v, but at 120v, so it'll need more like .6 amps.


Actually Mike, most peltiers I've come across use more watts than that. When I was doing watercooling solutions for computer processing, I'd come across 20amp 12v stand alone power supplies that were used for single processor systems! I think what might also be missing here is the fact that peltier also need a system to displace the heat to. How large and how many peltiers that need to be used will depend on how much heat he needs to displace...


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## defaced (May 23, 2005)

Order of magnitude is what I'm getting at. You could use a 40, 80, 100 or even 120 watt peltier in my example and after doing the power calculations to find out how much current the peltier circuit pulls from the wall you'd be a long way off of the 5 amps a small air conditioner uses. You'd need something obscene like a 450 watt peltier to pull 5 amps from the wall.


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## markbudde (Jan 4, 2008)

As summer rolls around again, I'm considering a peltier cooler. Do you have any results from this project, ie. it works like a charm, or is impossible?
Thanks,
Mark


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## allanschon (Mar 25, 2007)

The cooler stopped working for some reason when I was testing the unit out. Then, I had the controller I was planning on using miswired somehow, and I sent it up in smoke as well. I decided to just bite the bullet and run the apartment air conditioner.

The idea is possible, but you need to be a better electrical engineer than I am... If you manage to get it working, be sure to let us know. I will probably try this again, but not for a little while.


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## tkromer (Dec 20, 2007)

I've wired one of these up to cool an axolotl tank for a friend. We kept the water cooled to about 65 when his house was typically around 72-73. 
Some things to consider: It will essentially be on or off, there's no adjusting speeds, and cycling it is not very efficient as it takes several minutes to get "pumping". The outside needs good airflow, so a fan is a must, but also make sure the fan's not blowing into a cabinet or straight into a wall, if it is duct it out to the side of the tank perhaps. Inside the peltier will be spot-cooling the glass unless you have water flowing across it or a bunch of fins with a fan blowing across them, water is much better than air for conductivity of course. Peltier's don't work on AC so the amperage you have discussed is correct you will need a 12V (or 15 or 20) DC transformer to power the peltier and therefore you will be using several amps. Wall amperage wise I ran an 80W (12V DC @7 amps so actually 84W) and it used approximately 1.1amps from the wall. Efficiency losses in the transformer and maybe the peltier as well would account for that, that's about 132W AC to make 84W DC. 

In all, it worked well but if your house is hot it's not going to make much difference inside your tank. I'd say with maximum exchange you might be able to pull 10-12 degrees below ambient. Insulate 3 sides of your tank if you want that to happen.

If you need any wiring help or anything else PM me or continue the thread and I'll check back


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## postal (Aug 12, 2008)

I'm hoping this thread didnt die off.

I'm very interested in this.

10-12 below room temp sounds perfect for my situation.... I'm tired of icing my tank in summer....

I've done a lot of reading on the subject in the last week or 2- not much for people that have actually used them in vives though..

My big concern is how to install in a tank? Do you place the cool side directly on the glass? Or a false bottom, on the glass under water? Or maybe a heat sink with fan blowing cold air into the tank?

I worry about the glass cracking from a severe temp difference for direct glass contact, but a heat sink with fan to blow cool air would be much less efficient from what I've read....

BTW, this would be a 54 g corner unit with 2 wall sides foamed and the bottom insulated as well...


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## IN2DEEP (Aug 7, 2007)

I'm pretty interested interested in this topic too. Especially since we had so many power outages from the T-Storm Fay (did it make huricane? I H8 watching the news). I need something that can be ran off a car battery in emergencies.


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## allanschon (Mar 25, 2007)

This is still something I'm thinking about, but I won't be attempting it again for a while. I have too many other projects going on right now... I'm moving next weekend, and all of my tanks will be in the basement, so I won't need this for myself anymore, but it would be a neat thing to get working...

My plan had been to mount the cooler on the edge of an insulated box, with a fan+heatsink attached to the hot side on the outside, and the cold side on the interior of the box. Then, another fan would blow the air through ducts into the tank. I was able to get it working, as a prototype using a styrofoam cooler as the cold box, but ultimately, I think that the design may not be efficient enough to cool a full tank.

Since the device operates to keep the cool side at a temp differential from the hot side, if you used a water cooling assembly plus a larger radiator to cool the hot side, you could perhaps bring the cold box down a few more degrees. If you then coupled the cold side with a very large surface area heatsink, and integrated it with an in-tank air recirculating system, you might be on to something. That said, the system I just described would be significantly more costly than my original design... Also, one issue that I never really tackled was handling condensation as the hot tank air hits the cooler. That moisture needs to get back into the tank, unless you have an automated mister, any cooler will reduce the humidity in the tank.

In any case, if you'd like to try this, this http://www.allelectronics.com/make-a-store/item/PJT-10/LARGE-THERMOELECTRIC-DEVICE/1.html
could be a good start for building a basic cool box...


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## IN2DEEP (Aug 7, 2007)

Nice plan allanschon. I've been looking at alot of diy projects and it would appear to work. My biggest fear is finding the right power source. It seems every diy forum has contained atleast one horror story of HOT wires and even fire. So personally I'm looking for a manufactured unit, like portable coolers or wine chiller. I've got a good idea how to challenge the humidity issue. 

Just an added thought. Alot of the peltier diy forums were on saltwater nano aquarium sites. Most of the time threre best solution to combat heat was raise the lights and add fans to blow across the top of the water. I'm wondering if I could reduce temps by having a fan blowing across water under my false bottom? Although, I doubt it will reduce temps below room temperature.


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## IN2DEEP (Aug 7, 2007)

Good luck with the move allanschon!


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## LaserGecko (Oct 8, 2007)

tkromer said:


> It will essentially be on or off, there's no adjusting speeds,


Actually, you can use them proportionally by varying the voltage and/or current going to them. Running a 24V junction at 15V will move less heat.


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## postal (Aug 12, 2008)

I found a great little thread on kingsnake using a peltier cooler for a snake tank.

For snakes, it's common to have a warm side and cool side so the snake can pick the temp it wants. He had a difference of about 6? degrees.

I think *ideally* would be too cool the entire frog tank, but even getting a part of it down about 10 deg would would help.

He had a large aluminum block on the cool side as an "extension" which was mounted through a board. Then he attached a thick sheet of aluminum which was the cold sink. You could add a fan to blow cool air around as well. With this mounting, the cool side was on the bottom of a board, and the hot side with heat sink/fan was on top of the board, and he blocked it off to blow air out away from the tank. I think it's a great solution to try and distribute the cooling with both the large alu sheet, and a fan as well.

It's a great write up with some good ideas-
http://forums.kingsnake.com/view.php?id=1565681,1565681&show_threads=2


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## IN2DEEP (Aug 7, 2007)

Nice thread. Thanks for sharing postal!


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## postal (Aug 12, 2008)

FYI

I havent checked into them much.....

but- it seems that a laptop ac converter *MIGHT* be the perfect power supply.

Many of the peltiers I've seen on the net are 14/15 volts at 4 ish amps.

The laptop I'm using right now has an ac adaptor that is 15v 5 amps..... (toshiba satellite)

ebay or craigslist or an electronics clearing house may have a laptop ac adapter that is perfect for running a peltier..... Or if you know someone that works in IT... maybe a freebie converter from a dead laptop....


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## allanschon (Mar 25, 2007)

It depends on what other electronics you have running, but an old computer power supply might be useful as well. That way, you'd have easy access to a 5V power source as well... Worst case, most power supplies would provide plenty of amps to run a cooler and a large number of small fans. Also, if you build a DIY misting system, many pumps run on 12V as well.


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## VivCred555 (Oct 6, 2008)

The question is, if you are using it with a heat sink and fan to simply blow cold air into the viv, can you keep the unit running continuously without it overheating?


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## postal (Aug 12, 2008)

VivCred555 said:


> The question is, if you are using it with a heat sink and fan to simply blow cold air into the viv, can you keep the unit running continuously without it overheating?


You need the heatsink and fan on the hot side to keep the unit from overheating. If the sink is efficient enough it can run continuously. The hot side MUST have a heatsink and fan. Some people were talking about sink and fan on the cold side to blow cold air around the tank as well.

I will wait until new year to work on one- since I got through the summer.

I've decided to ask for a peltier wine rack for xmas... which will include almost all the parts I need, even a basic thermostat. I would probably try it cooling the air just to see how it does, but my new plan, is to mount the cold side with an aluminum finned heat sink into a watertight box, and pump water through it. My tank has about 4.5 gal water... so if I can maintain a low water temp, it should keep the entire tank cool enough.

When I dont run the AC, my house can get to about 86 deg in the afternoon. If I can maintain a cold water temp closer to 64, the water itself would be a cold sink and the tank would resist warming. Naturally, the water temp will rise... but I'm guessing, that if water stays below 70, tank temp *might* stay below 80... Of course there would be a temperature gradient from the bottom of the tank to the top, since the cold water at the bottom, and the hot lights at the top... but I think this idea has the best chance of success.

Wont be til next yr, but I'll post about my results.


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## nish07 (Mar 16, 2008)

I was considering running one or two peltier aquarium chillers into the false bottom of a tank to cool it (montane tree frog tank). The chillers are sold at approximately 100 dollars and fit through a hole and are bulkheaded to seal. They're meant to cool between 50 and 65 degrees F (one of the two models I've sen sold). Two can be added for more of an effect, however, if all they were to be used in was a false bottom of about 3-4 inches of standing water, it should cool fairly well. I'm not sure how much this cooling will then cool the whole tank. It might be possible to rout fans below the substrate and above the false bottom to circulate cool air. Either way, chilling false bottom water to 15 degrees below room temp should cool the viv somehow (fans blowing heat from the lights would help too).

If anyone has a better way, let me know.

-Nish


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## Dancing frogs (Feb 20, 2004)

nish07 said:


> I was considering running one or two peltier aquarium chillers into the false bottom of a tank to cool it (montane tree frog tank). The chillers are sold at approximately 100 dollars and fit through a hole and are bulkheaded to seal. They're meant to cool between 50 and 65 degrees F (one of the two models I've sen sold). Two can be added for more of an effect, however, if all they were to be used in was a false bottom of about 3-4 inches of standing water, it should cool fairly well. I'm not sure how much this cooling will then cool the whole tank. It might be possible to rout fans below the substrate and above the false bottom to circulate cool air. Either way, chilling false bottom water to 15 degrees below room temp should cool the viv somehow (fans blowing heat from the lights would help too).
> 
> If anyone has a better way, let me know.
> 
> -Nish


Perhaps add a drip wall to the plan?


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## nish07 (Mar 16, 2008)

Well my idea was that it'd cool the water so cold that you didn't really want it to touch the frogs (they'd would get hurt from the low temp water) but that it'd absorb the heat from its surroundings (the viv) and therefor cool it down. It'd at least cool the lower half of the viv down some but it all depends on how much the chiller was able to cool. I'd imagine quite a bit since they're made for 55g full aquariums and you're only chilling 3 inches of standing water in a false bottom. If only you could insulate all sides of the viv from the false bottom water then you'd be cooling the viv more since the cool water will be absorbing heat from the environment outside of the viv.

-Nish


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## postal (Aug 12, 2008)

My tank is a corner unit with both back sides and the bottom insulated.

I have about 2 inches of water which is about 4.5 gal. Controlling the temp of that much water should have a significant effect on the entire tank. I also have a waterfall made of lava rock, so cold would transfer to the waterfall as well.(and from the waterfall to the air as well)

I've seen the type of cooler that requires a hole to be drilled through the glass, and there is another type with hose connecters for water to be pumped through it. I want to copy that idea of pumping water through it.

If the water temp doesnt go below 64 or so, it wouldnt be too cold for the frog. If most darts can handle temps down to 60...


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## smallac (Jun 4, 2010)

LaserGecko said:


> Actually, you can use them proportionally by varying the voltage and/or current going to them. Running a 24V junction at 15V will move less heat.


Thank's a lot, I have the similar question


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