Heat/Cool thermostat


Just received. 20 bucks


Hey Jodie, I think I see where you are going with this. And it seems like you might be on to something. I like the way you think! You go girl!

Anyway, i did some research on buying Peltier Cooler modules and was of course inundated on google shopping by tons of websites that I have no experience with and have never heard of before. However I did see a few from New Egg.

While there might be better prices out there on e-bay or other websites, I like New Egg for electronics online to broaden my options from some of the more mainstream options. NewEgg has actually been around a long time, they used to be Egg Head Software and Computers. New Egg is kinda like amazon, in that it has its own stuff, and it has small retailers that sell through them and have to live up to the requirements for return policies and such much like amazon with its smaller retailers.

Anyway, I found these:




Reversing this design, one could easily make a water chiller to re-circulate your reservoir’s water through that would chill the water. You could use the extra large can tomatoes come in as opposed to a coffee can, as tomatoes are acidic and so the inside of the can will be coated to be resistant to the slightly acidic nature of the reservoir’s water.

Steal the parts from one of these:

Actually, maybe not even steal the parts and attach them to a coffee can, that would be for starting from scratch. Use this fridge as your "cooling reservoir. I just bought one, at that price I don’t think it can be beat.

I think that unit has potential. Through the years I have been researching; I have found many great tools bu using good old American ingenuity. I would look around and shop for the best price you can get that for. This is the type unit that might be great for a custom built room. running AC, and Heat…Or; Maybe running a dehumidifier that does double duty. Heat output, and lower humidity.

Just a thought. :smiley:

I’m not sure what you mean. This 7 liter refrigeration unit might add a little heat in the grow room if placed inside it while still keeping the reservoir around 70*F. Heating the room a little, especially when using LED lights might be a good thing as the canopy could use higher temps as LEDs don’t heat the canopy like HID lights do. When used as a remoter chiller reservoir it will not add heat in the grow room itself and it won’t do anything for humidity one way or the other. I think it would be more effective as an outside the room remote chiller reservoir as it uses a Peltier superconductor heat pump, not the same as freon or other compressed gas type air conditioning or refrigeration, as the amount of cooling will is directly proportional to the outside temp, the cooler the outside temp the cooler the inside of the fridge…This fridge normally runs in the $60 to $70+ dollar price range and is going for under $34 with free shipping. I’m still thinking about this specifically for Jodie’s grow with her High Power LED lights and her idea of having the canopy warm and the reservoir cool.

Oh, the coffee can rig might be confusing. I said reverse that design. The reason the heat sink was freezing over was because the water was being heated not cooled in that video. If the set-up was reversed to cool the water passing through it, the heat sink would be hot, no condensation, if that is what you were referring to. Yes, in the water heating fashion the condensation on the heat sink would work as a dehumidifier.

BTW, so this type of Peltier superconductor heat pump refrigeration won’t have a condensation tray like traditional refrigerators.

I just go the thermostat wired. ***be aware, the instructions in the box, English written by a Chinese person with little skill in English, are worthless; however, there are dozens of Youtube Videos on this. I found one by a typically anal German, which was perfect. This thing will run BOTH your heat/cool devices and does so automatically, once set up. ***** You could use this for home brewing, growing, hydro, your home furnace, what have you. Any thing up to 240 volts. I think this is a very useful piece of equipment to have in one’s repertoire. Judging from the number of instructional videos, must be tremendously popular, so they must, I infer, be reliable.

I ought to have given an example of application. I’m using CO2, so I only want to vent when the temp get too high. So this will now kick on the fan, and kick it off at approx 6 degrees lower. I will undoubtedly be hooking up a heat source at some point in the near future, thereby achieving a very controlled temp. :wink: Techno Granny.

Ok, so you likely have different plans for a thermostat than I thought you might but I did order the 12V mini fridge and I have thoroughly taken it apart. It will work for what I have planned. It is only 7 liters and so it might not be able to cool the reservoir enough all on its own. And so I ordered the two pack of Peltier superconductor heat pump/joule theif modules from NewEgg to add to the mini fridge.

The internal bottom 2/3rds of the mini fridge is a aluminum tub, so the entire bottom of the mini fridge is the heat conductor. It is enamel coated on the inside and so it can be made to hold a small amount of water, but they attached the Peltier to the aluminum tub with screws drilled into the tub. Not a real big deal as these screws and screw holes can be waterproofed with aquarium silicon. The aluminum bottom is not that much different than a aluminum slow cooker, the type with a removable pot that could even be used on the stove top, not the ceramic crock pot type but it is only about a 3 liter in capacity. As it is all aluminum I can attach the two other Peltier modules individually to either of the three remaining sides with a little work. This should be able to provide enough additional removal of heat from the inside of the mini fridge to quite effectively cool the 18 gallons.

The additional two Peltier modules might not be necessary, especially if I don’t let my grow room’s air temps get too high, but as you want to have a higher canopy temp, I had that in mind and want to try running a few tests to see how much I can get way with if I run the mini-fridge outside the grow room with a recirculating system of 1/2" I.D. black vinyl tubing. I don’t think I’ll try using the 1.5" I.D. pvc or abs pipe as it will be a lot more work and much more difficult to run the chilling reservoir outside the tent and still be connected with non-flexible large pipe.

I’ll likely attach the two Peltier modules with Thermal Adhesive which is also required for making LED strips/groups on a aluminum heat sink. Using the adhesive I won’t have to drill any new holes in the aluminum tub and I probably will use it for the original Peltier as well so I can be very sure the holes are completely covered by the aquarium silicon and not get any aluminum leeching into my reservoir water if things get a little acidic. BTW LEDs are also made of superconductors.

I will start a new topic “build your own reservoir chiller” and post updates, I just wanted to update here as I had posted all those you-tube vids about Peltirers.

One foot in bed, but I am compelled to comment. Very good idea to put the cooler outside the g.room!! Love it. Yeah, well, when I was reading up on these plates, whomever was doing just as you are - using multiple units to acieve the temp they desired. Of course this is quite dependant on the size of the res. But no one, my dear Mac’, thought of doing what you are. Good thinking.
I’m using the thermostat for cooling/heating the room; however, the probe is submerible, coated in a rubber-like plastic substance. And the range is ridiculous, something like 50 C below to 100 C above. Which boggles the mind as far as what type different situations it might be useful.

See ya tomorrow. Grammy is tired…