The Ultimate Budget ($8.20) Fog Chiller




With only the absolute simplest of tools, and fewest of supplies, one can construct a superior fog chiller.

The fog chillers currently on instructables are a variation of the "fog on the rocks" design, but have a few shortcomings that small changes can correct.

For less money we can construct a re-useable fog chiller that will cool more fog, requires less ice, allows for more fog to be produced, and is considerably easier to assemble.

If you're looking to build a fog chiller, this is the one you should build.

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Step 1: Justification, Design Changes, Theory, and a Few Little Tips for Avid Chiller Designfolk.

There are two primary design differences between this chiller and the other chillers on this site.

The othertwo are examples of the "fog on the rocks" design that has been popular with home haunters since 1995.

The "Super Cheap and Easy Fog Chiller" doesn't produce a lot of contact time between the fog and the cold, resulting in less cooling. I imagine that a great portion of the fog simply blows clean through, the second design forcing the fog to sink is a better one.

The Fog Chiller for $10 blasts the fog directly into the wall of the cooler box, this is bad, more on this in two paragraphs.

Both of the other two chillers use styrofoam cooling chests as their chilling box. This is a rather bad plan for a simple reason, the fog eats into it and becomes toxic. The chillers are not exactly reuseable, your fog becomes toxic, and I hate the squeaky sounds styrofoam makes.

So, changes? The important one is the "fog cage". This is a gap between the nozzle of the fog machine, and the chiller. This is important because for the fog to form properly, optimally, and in maximum abundance it must mix with a LOT of air immediately. If it comes into contact with a solid object, or is in an air starved environment you end up with less fog. Less fog means you need more fluid and and a more powerful machine. Costs go up, way up. The change in the amount produced through the use of a fog cage is very dramatic. Those who have already built the styrofoam chillers should give pointing their fog machine into their chiller from a distance so that they can get the benefits of the extra fog without the extra work of making an extra chiller.

Second change is simply switching from a styrofoam chiller to a regular ol' plastic tub. It doesn't react with the fog, it's tougher, and you can store some of your halloween stuff it when the day is done. You may think the ice would melt faster, but the primary source of heat isn't ambient, it's the really really hot fog you're blowing in one end of your chiller (duh). Also, in my tests the chiller in the photos keeps the ice for about 7 hours of use with an automatically cycling fog machine.

Step 2: Materials and Tools

1 38L (10 gal) storage tub - $4.50
2' Chicken wire (or hardware cloth) - $0.86/foot
2 PVC couplings - $0.99/ea @ building supply store


Glue gun and glue
Metal shears

Step 3: Chicken (wire) Chop

Flip your tub over, outline the shape on chicken wire with a good marking device of some kind. Or just hack it up all willy-nilly. It's up to you.

What you want in the end is a rectangle vaguely the size of the top.

Take the chicken wire, and put it aside for now, you'll need it in just a second.

Step 4: Ice Tray Feet

Next you'll want to fabricate a set of feet for your ice tray to sit on. The feet need to be taller than the diamter of the coupling. You can construct the feet many ways; out of wood, bits of things you have lying around, cut up pvc couplings, whatever you like.

The feet I like the best are rolled pieces of chicken wire. The materials are already there, they fit well, and the holes guarantee proper airflow.

The easiest way to make wire feet is to roll them around something, and be careful not to gash your finger open.

Make sure the feet are all mostly the same height. Exact isn't too important.

Step 5: Think, Measure, Think, Measure Again, Cut.

It's time for you to decide where you want your chilled fog to exit the chilling box (keep in mind the entrance will be on one of the narrow sides of the box). Take one of the couplings and trace a circle there.

Next, take the other coupling and measure a circle near the top of the box. Line up the top hole so that the opening faces into the box the long way. Remember you want the fog to touch as little as possible for as long as possible to allow for maximum mixing with air, and maximum fog production.

Cut out your marked circles, remember cut inside the lines to stop from cutting too much. Another tip, a hot soldering iron is extremely practical to cut through thin plastic. Just don't breathe in.

Insert the couplings, and try to keep them as flush on the inside as possible.

Lastly, seal up the holes with hot glue. Sealing from the outside, and then from the inside makes the process much simpler.

I know, this step is almost too documented in relation to the others. But I figured this one was easiest to show through photos.

Step 6: Drain Holes (optional)

If you plan on placing this outside, fill the underside with holes so that water has an easier way to drain.

Don't do what I did and place the first holes in a part that's raised, because it won't collect water (oops).

Step 7: Assemble

Place feet inside tub, cut corners out of tray, fold up corners of tray and shove until it rests mostly on the feet (the ice will hold it in place)

When you go to store it you can just fold the flaps the rest of the way over and store them pointy bits down, allowing it all to pack flat.

Step 8: Finishing Touches

Cut a piece of chicken wire at least 6" long and wide enough to wrap around the pvc coupling. This cage will allow for easier lining up of the nozzle and the opening. And also force the gap needed to produce the most fog for fluid heated.

Toss in some ice, throw on the lid, heat up the fog machine.

Step 9: Eat Some Stewed Brains

A good snack while waiting for the fog machine to warm up.

Step 10: Action!

Fwoosh, fwoom, blub, and other sounds creepy ground hugging fog makes.

Here it is in action, lower, thicker, and all around better fog.

Note that it was very windy, and very bright, and the fog is still very visible, and hung out for a good long while.

Step 11: Bonus Mini Instructable!

Did you think we were going to just throw out the pucks we cut out of the box? That'd be wasteful!

Instead, we use our soldering gun to carve them into the ever handy skull chips! Handy for what? Nothing of course!



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    38 Discussions


    9 years ago on Step 6

    what should you do if you use this in-doors? do you need to drain it manually so it doesn't leak water out the pipes?

    1 reply

    2 years ago

    I have a really stupid question, because you all seem so knowledgeable when it comes to this stuff - and I am so NOT. LOL

    With the chicken wire tube leading from the fog machine to the coupling, in the photo it looks like the fog would all escape before entering the chiller. What am I missing?


    4 years ago on Introduction

    Both couplers are completely unnecessary. I've made numerous chillers. Blow the fog in one hole, and it will come out the other.


    8 years ago on Introduction

    Easy to follow & make.
    Pics are of my fog chiller (I painted the plastic tub black)
    Instead of using silicon sealant to seal the PVC coupler, I splurged (I saved $ because I didn't have to buy the wire mesh, it was left over from a previous project) and used a 2"-1.5" reducing coupler bushing. (viz other pic)
    The fit was quite snug, I had to persuade it the final bit with a rubber mallet.
    But I think it is a much stronger join


    9 years ago on Step 10

    I had an idea: How about cutting three slots, maybe an inch above the bottom of the tub. The holes would be rectangles, about 1.5 Inches tall, and a little less than a third of the width of the tub end. The slots would leave some vertical support (by leaving plastic between them). This would allow the fog to sheet out of the bottom of the tub, pre-laying it flat on the floor. Dunno if it would work appreciably better, but it might allow for easier "hiding" it behind a curtain raised just a few inches off the floor.

    3 replies

    Reply 9 years ago on Introduction

    I think thats a good idea.. To me the coupling at the exit is redudant.. It couples to..... to nothing! Just cut a hole and save yourself a coupling.

    I might also try a small fan on the inlet sucking air (and fog) into the chiller box. With a layer if ice above the exit path it seems to me that the box is a bit of a dead end for low velocity fog. surely not all of it is drawn in.

    Great instructable..



    Reply 8 years ago on Step 10

    You don't want to suck the fog through a fan. The fan blades will agitate the fog and ruin it. It would be better to devise a way to push the fog and air. Try attaching a PVC Y-Connector to the coupling on the exit of the chiller. You could then place the fan in the Y, which would draw air and fog out of the chiller and push it along the exit of the PVC connector. Plus, you could connect longer pieces of PVC pipe and distribute the fog where you want.


    Reply 9 years ago on Introduction

    In actuality neither coupler is really required, it just makes things considerably easier.

    I am going to be posting the vastly improved

    "Perfect Chiller"

    some time soon, keep an eye open. 


    9 years ago on Step 11

    You could route a small amount of fog to come out of like say a soup can with one of those on the end producing cool rolling smoke to come out of his eyes or nose or whatnot, damn, I just thought of that. thats a good idea. Thanks for the idea!

    2 replies

    Reply 9 years ago on Step 11

    I'm glad this little silly step helped anyone out at all. Let us know how your soup can chiller and smokey skull goes


    Reply 9 years ago on Introduction

    hey extend the picture box where it says ice obscures exit hole because paople cant read it.


    10 years ago on Step 5

    Would it make sense to use a male adapter instead of a coupling? you could put the threaded end inside the box, and secure with a conduit nut on the inside and outside

    1 reply

    Reply 10 years ago on Step 5

    It would indeed. This chiller is designed to follow best practice as closely as possible, while being as cheap as possible. There are many minor improvements that could be done, but unless they net an improved output at a similar pricepoint I opted not to add them. While an adapter would make it easier to construct, and look a little tidier, it would be more expensive and the only possible outcome is very slightly worse performance (if we're being pedantic; due to turbulence caused by the conduit nuts shape).


    10 years ago on Introduction

    nice! i was going to make one of these, then i remembered, i'm in Canada! and it's October! It's cold already!

    1 reply

    Reply 10 years ago on Introduction

    Actually, that makes it more necessary. If your fog isn't colder than ambient temperature it'll rise. If however the ice isn't even as cold as outside... well, you're up an unmentionable creek. Paddle free.


    11 years ago on Introduction

    lol, same walmart fog machine i would be very worried about the fog leaking out of the top hole- i originally tried leaving a gap with my chiller, but as soon as the machine shut off, all the fog poured out the top. it is possible that your bin is big enough to have the fog stay in the bin and not leak out. so, how much does leak out once the machine shuts off?

    1 reply

    Reply 11 years ago on Introduction

    It seems to me that the height of the box (or more precisely, the height difference between the inlet and outlet) is the main factor here. Since you're relying on the density of the cooled air to force it down and out the exit, you've essentially built a smokestack in reverse. Using a taller structure and suspending the ice higher in it would produce a larger column of chilled, sinking air. That would make it "draw" better, and you shouldn't have any trouble with airflow reversing when the machine shuts off.