Introduction: Ultrasonic Humidifier

Ever since moving to the desert I've spent a lot of time trying to find a humidifier that meets my needs. Humidity here rarely exceeds 15% which isn't really the best environment for me or my dogs. The purpose of this instructable isn't to show you the cheapest way to do things, nor is it to reinvent the humidifier. This design is economical, efficient, and easy to use and clean. Most importantly, it can be sized to meet your specific needs. It can be upgraded and modified without having to be replaced.

I designed this project using 16 quart Ziploc storage containers. What's nice about these particular containers is that they have a gasket in the lid and they seal pretty tight. If you can find them, they do come in black, however I highly recommend the clear as it makes it easy to confirm everything is working properly and to know when they need cleaning.

I'll also add that this type of humidifier, Ultrasonic, works best when used with RO (reverse osmosis) water. Whether you're building your own, or buying one from the store, RO water is almost required. The reason for this is minerals in water. Depending upon the chemistry of your particular water, Ultrasonic humidification can emit a white dust like exhaust which is comprised mostly of dissolved minerals. Dissolved minerals in the water will also lead to require frequent cleaning to remove build up of deposits. Whether you're hard plumbing this, or using it with a reservoir tank, plan on using RO water.

Step 1: Before We Get Started

You'll need some things before we get started. This is a highly versatile design with several parts that can be substituted to make it more powerful and add functionality. In the parts list, where possible, I've listed alternative items and an explanation of the benefit or drawback to using the item.



Utility Knife

2" hole saw

15/64 Drill Bit

9/64 Drill Bit

Unibit (3/4" min)

Measuring Tape or Ruler


Screw Drivers


(I've included links for reference only. In some cases these links may go dead or prices may change. Please verify the item you are purchasing is the best quality available for the price.)

1. One (1) or Two (2) 16 Quart Ziploc Storage Containers. Second container is needed if you want to add a reservoir tank to your Humidifier. Unless you're planning on plumbing it directly to an RO water source, I highly recommend it. You'll need a few additional fittings for this which you will find later in the list.

2. One (1) 24v 60 x 60 x 25mm fan:

3. One (1) Adjustable Power Regulator/Converter (For fan speed control, also allows use of 24v Fan with 48v Advanced configuration Power Supply)

4. One (1) float valve:

5. One (1) Flange for Exhaust Port:

6. Four (4) 1/4-32 X 1/2" Stainless Machine Screws

7. Four (4) #8-32 X 1 1/4" Stainless Machine Screws

8. One (1) Ultrasonic Fogger:

Or, for advanced setup with very high output:

* Note: This is the heart of the Humidifier. You can use 1, or 10 of these just be sure to purchase a power supply capable of sustaining multiple units. Power supply recommendations are covered in item #9

9. Power Supply:

For one unit plus fan, purchase a fogger like the one listed in item #8 which includes the power supply.

For 2 or 3 units, plus the Fan:

For 4+ Units, or Advanced setup fogger:

10. Appliance Cord:

*Note: For Advanced setup only using 48v power supply

11. 5.5x2.1mm Power adapter Ends with Screw Terminals:

12. 5.5x2.1mm 1 Female to 4 Male Power Splitter:

*Note: Not needed for use with 48v fogger

13. 1/4" Polyethylene Tube:

*Note: You only need about a foot of this stuff.

14. Fittings for use with 2nd Ziploc Storage container as Reservoir Tank:

One (1) Through Fitting for 1/4" push connect tube:

One (1) 1/4" Push Connect Ball Valve:

15. Ball Valve for use with plumbing directly to RO water filter:

Step 2: Cutting the Fan Hole

Cutting the Fan Hole:

Stand the container up the long way and place your fan in the center right to left, and to the top up against the rim. Mark the center of the Fan in this location and prepare to cut your hole. I find it easier to drill a pilot hole in the center prior to using the hole saw. Place your 2" hole saw in the drill and make your cut.

Step 3: Drilling the Fan Mounting Holes

Place your fan centered over your 2" Hole. Mark the center of one hole with your marker, remove the fan and drill it. Place the fan back over the hole and use one of your #8 screws to hold the fan in place. Insert the screw while applying downward force with your screw driver to cut the threads into the plastic. Take care not to over tighten.

Now that your fan is being held in place, using the fan as a template, finish drilling the remaining 3 holes. Next, remove the screw and set the fan aside for later assembly.

Step 4: Trimming the Exhaust Port

Place your Hose adapter with flange Flat on a table and using a utility knife, cut along the 3rd ridge as shown in the photograph. You can discard the smaller piece as we move on to the next step.

Step 5: Cutting the Exhaust Port Hole

Flip the container over and stand it up the long way to access the other side. Place the Exhaust port flange with the larger side (the 2" side) toward the container. Center it side to side and push it up against the rim. Using your marker, mark around the adapter and locate the center. Drill your pilot hole using one of your smaller drill bits then insert the 2" Hole saw into the drill and cut the hole.

Step 6: Drilling the Exhaust Port Mounting Holes

Insert the larger end of the exhaust port into the hole. (you may need to enlarge the hole slightly using your utility knife). Using your marker, Mark each of the 4 holes in the flange. Flip the container over so that you can access the inside of the marked holes. Place your 15/64" drill bit into the drill and drill your holes from the inside out this time.

Step 7: Drilling the Float Switch and Power Cord Holes

We've got 2 holes left to drill, one for the float switch, and one for the power cord(s). These holes go on either side of the fan. They will both be about 5/8". Locate the narrow flat area on either side of the fan hole. Measure up from the bottom of the container 4.75" and make your mark in the center of the flat area; one on each side.

Put your Unibit in the Drill and drill the hole to the 5/8" ridge. Repeat this for the other side. You'll most likely have some excess plastic protruding from the inside of your new holes. You can trim this off easily with your utility knife.

Step 8: Assembling the Parts

Place the exhaust port into the hole and using firm downward pressure, screw in your 1/4" screws. Take care not to over-tighten these. If for any reason your holes have come out too big, you'll have to use nuts to secure the screws.

Next, flip the container over and do the same for the fan. Most fans spin clockwise, so observe the fan blades as you install the fan to be sure it will blow inward. Plug the fan into the power supply temporarily to verify you're installing it in the correct direction.

Remove the nuts from the float switch and insert it into one of the 5/8" holes. I chose the right side for mine. Part of the nut assembly for the float switch is a gasket and a plastic washer. The gasket goes on the inside of the container and the washer goes on the outside. You're going to need to adjust the float switch to maintain the proper water level later. You'll do this by loosening the screw on the float arm and adjusting it up for more water and down for less. It's very important that the water level never comes within 1/2" of the fan.

Step 9: Plumbing and the Optional Reservoir Tank

Plumbing is pretty strait forward. Your float switch came with a 1/4" quick connect elbow. Plug that into the back of the float switch. Cut a few inches of your 1/4" tube and plug that into the elbow. I like to put a ball valve in line here, but it's not really necessary. If you're hooking this up to a water supply all you have to do is plug it in and adjust the float valve. Anywhere between the top of the sensor on the fogger and up to 1/2" below the fan is fine.

If you're doing the reservoir tank, you'll need to measure the width of the through fittings for the hole. You're going to want to drill the hole for the fitting in the center of the short end of the container as close to the bottom as you can get while still allowing sufficient room for the gasket and nut.

Once you've got that figured out, put that unibit in the drill and make a hole. Don't drill the hole any bigger than you have to. This fitting sits below the water line, so you need to get this part right. Also, remember the gasket goes on the inside.

Once you've got the fitting installed, cut off another few inches of tube and plug it in. Then add the ball valve (making sure it's in the closed position) go ahead and water test it for leaks.

If you've got no leaks, affix the lid and set it aside.

Step 10: Wiring It Up; the Basic Version

Grab your step down converter which will function as our fan speed controller. It really doesn't take a lot to move air through this thing, so this little doohicky will give you the ability to adjust the fan speed to your liking. If you didn't get the one in the picture, no worries, they all pretty much wire the same. You're going to connect the fan to the motor lugs, make sure to note the polarity.

This model has a readout for voltage. In this configuration, 24v is full power. As you turn the dial down you'll see the voltage drop, turn it down too low and the fan will stop working. Next, you're going to need to use one of the Female screw terminal connectors to connect the power side to the adapter. In order to do this you're going to need a piece of wire; one for the + and one for the -. If you don't have a piece of wire lying around you can simply cut a few inches off the fan wire and use that. Again, make sure you note the proper polarity. For all you lazy readers, I'm going to mention something I think it very important. If you're building the advanced version and you're using a 48v power supply, the step down converter is doing more than speed controlling our fan, it's keeping it from burning up from overvoltage. Whatever you do, do NOT operate the 24 volt fan above 24v. Next, Place the Fogger(s) into the Container and pull the wire(s) through the hole. If you're using the 3 amp power supply shown in the image you can run up to 3 of these plus the fan. Plug in the 1 to 4 adapter to the power supply and 3 of the ends to the Foggers. Then, Plug in the fan.

Step 11: Advanced Version

If you're doing the advanced version of this project and you're using the larger adjustable power supply, this is your section.

I chose this 10 amp adjustable power because it's so versatile. If you're using more than 3 single foggers, this power supply will run them. Set it to 24v get a few more 1 to 4 connectors and you can run 11 foggers and a fan, or 12 foggers and wire the fan directly. The do sell 1 to 8 connectors and you might be tempted to use one, but I advise caution with those as the load is more than likely going to be too high for the cheap ones to handle.

You're going to need a few extra things for this configuration as listed in the parts list. This power supply does not include a power cord so you'll need one. You can purchase one from the link provided, get one from Home Depot, or cut the end off an old computer cord. Just make sure it's grounded. You're also going to want a piece of wire to extend the fan cable.

Wiring it up.

This power supply operates on Line Voltage which is 120v. Although this is very basic wiring, if you don't feel comfortable working with line voltage, please don't. This instructable is in no way a replacement for the manufacturers specifications or instructions. Please follow all manufacturer recommendations, local and state building codes and those of any other relevant authorities on the planet Earth.

Now that we got that out of the way, Grab your power supply and your power cord and wire it where indicated. before connecting the load side of the power supply, lets plug it in and adjust it to the proper voltage. Select 24v or 48v based upon the fogging device(s) you're using. This is important as if you accidentally connect a 24v fogger to a 48v configured power supply, you'll be ordering a new fogger. You should have read the operating instructions for the power supply at least twice by now, but just to make sure, verify the power supply is set to 120v before plugging it in.

Now that we've got that done, unplug the power supply form the wall outlet. If you're using the 12 head brick, place it in the container and run the cable through the hole and out to the power supply. If you're using multiple single units, connect your wires with the proper connectors out to the 1 to 4 connectors. Connect it to the output lugs along with the wire from the step down converter to the fan. You'll probably want to keep the step down converter and the power supply close together and out of sight if possible.

Once you've got the step down converter and the brick (or single fogger units) wired properly and you've verified it a couple dozen times, plug in the power supply. Make sure that the step down converter is not reading more than 24v and go ahead and plug in the fan.

That's pretty much it. I hope you enjoyed doing this project as much as I've enjoyed bringing it to you. I'll be adding a section on installing a humidistat soon. I've got a wifi version you can control with your phone for under $15!


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