Installation for Semis

Important Safety Notes

HHO (hydroxy gas) is highly combustible, volatile, and explosive. It is no more dangerous than any other fuel, but only when it is used properly. It is important for your installation is to make sure that HHO is only being produced when the engine is actually running. For instance, you don't want HHO being produced when you are sitting in your truck with the accessory switch on, listening to your radio. So the key is to find a circuit that is only on when the engine is actually running. These instructions will tell you how to achieve this product. Just realize the importance of getting your installation done in a way that will achieve this goal.

Other safety points to consider:

  • NO spark or flame should be allowed near HHO gas.
  • Do not operate the Dry Cell indoors or in the passenger compartment of your truck.
  • Use eye and skin protection when mixing or handling electrolyte.
  • In the event of eye or skin contact with the electrolyte, flush with plain water.
  • Mix and store electrolyte in heavy-duty plastic containers - keep away from children

Assemble the following items in addition to those provided in the Dry Cell Kit:

  • Voltmeter or multi-meter
  • Basic tools: wire stripper, screwdriver, pliers, etc
  • 2 gallons steam distilled water for electrolyte (make sure it says "steam distilled")

Assess the space available for installing the components. You must find or create space for the following components:

  • Dry Cell
  • Reservoir. Note: the Reservoir should be installed above (i.e., higher than) the Dry Cell(s) to facilitate the flow of electrolyte into the cell.
  • Dryer Assembly
  • PWM

1. Mount your components

Mount your cell, reservoir and bubbler assembly. Make sure the reservoir is higher than the cells, as water must feed to the cell by gravity. In addition to the components below, find a place near your cell for the PWM, minimizing the cable length between the PWM and cell.

Tubing Connections

The reservoir provides water and electrolyte to the cell. Electrolyte goes out of the bottom reservoir fitting and goes to the bottom fitting on the cell. HHO gas and electrolyte comes out of the cell at it's top fitting. The electrolyte drops back into the reservoir. The HHO gas comes out at the removable fitting on the reservoir's lid. Note, that it is important that the lid be screwed down securely so that you don't waste your HHO gas.

Your dryer assembly is used to remove any water that may escape from the reservoir. It is composed of 2 reservoirs with 5 micron filters in them. You should periodically check these and empty them if needed. Systems that are run too hot (amps too high) will tend to get water in these reservoirs due to condensing water vapor.

1a. Mount your components - Premium Reservoir Option

The schematic diagram below shows how the components go together. And while it is a schematic diagram, there are some important points to keep in mind. First, the reservoir has to be above the cell. If the water level inside the reservoir falls below the top of the cell, the cell will only partially fill. This should be avoided by keeping the reservoir above the cell.

Tubing Connections

The dryer needs to be installed so that any liquid that escapes the reservoir, will fall back into the reservoir by gravity. So the positioning of the dryer in the schematic diagram also shows how the dryer should be installed in relation to the top of the reservoir. See the picture below for an example of how this work. Notice that any electrolyte that gets out of the top of the reservoir, will fall back down into the reservoir.

Tubing Connections

Everything else is straightforward. Just follow the diagram. You can extend the hose as needed to reach from one component to the other. As long as the instructions in the 2 paragraphs above are followed, then you will be fine.

2. Make the tubing connections

Connect tubing between the cells and the reservoir as shown in the diagram. Notice that the lower fitting on the cell connects to the lower fitting on the reservoir. This is for the flow of electrolyte into the cell. The upper fitting on the cell goes to one of the upper fittings on the reservoir. This allows the HHO gas to flow to the reservoir. Any electrolyte that is pushed up this tube will drop into the reservoir.

The fitting on the cap of the reservoir is for the HHO out to the dryer, and then on to the engine. We put the output fitting in the cap to minimize any electrolyte that might slosh around while the vehicle is in motion. Any electrolyte that gets into this hose will be pushed forward to the dryer and require it to be emptied more often. We minimize this by putting the gas output connection in the very center of the reservoir.

When connecting the hose to the fittings, slip a hose clamp onto the hose before slipping the hose onto the fitting. This is easier than trying to retro fit the clamp later, after the hose is already slid onto the fitting. If needed you may use a heat gun (or hair dryer) to warm and soften the tubing to get it to slip more easily onto the fitting. Another trick is to use a little liquid soap which will cause the tubing to slide over the surface of the fitting.

At the air intake for your engine, you will need to drill a hole to fit a 1/4" NPT threaded fitting. You want to drill this hole into one of the plastic air channels that leads to the engine intake. The size of the hole should be 7/16". If you have thick plastic or metal where you are drilling your hole, then you will need to tap threads into the hole. In this case, use a 1/4" NPT tap. We provide a threaded elbow that will screw into this hole. If you were unable to tap the hole, use some clear silicone sealant to ensure that this connection is air tight.

The Drain T shown in the diagram should be routed to a place where you can reach it easily. It is meant to be used when you need to drain the system. You should tighten the nylon nut with a wrench. Finger tight won't be tight enough to prevent leaks. There is a rubber washer in the cap that will allow a seal to be made.

Now you can complete the tubing connections to all the devices as shown in the diagram above. Go ahead and make your hose joints permanent by tightening down the clamps. Push the hose onto the fitting as far as it will go. Don't put the hose clamp directly over the fitting's barb. Instead, place the hose clamp so that it just behind the barb (closer to the rest of the fitting). Then tighten it down. This is the way to achieve a leak-free joint.

Tip: You can use a little liquid soap to make the hose slide onto the fittings more easily.

3. Mix your electrolyte and fill the reservoir

It is very important that you use steam distilled water only. Look closely at the label. Filtered water is not good enough. Neither is reverse osmosis. Do not use tap water, mineral water, spring water, or purified water. It must be "steam distilled". The proportion of potassium hydroxide (KOH) to distilled water is approximately 1/4 cup per gallon. This will probably be a little less than you actually need, and small adjustments may be necessary. But it's better to start this way because it's easier to add a little KOH than to dilute the mixture when you may not have room in the reservoir for more water. Later, if your system will not come up to your desired amperage, add a little KOH. Note that added KOH takes some time to get absorbed into the system so give it some time before you add more.

Add the included defoamer to your electrolyte mix. It will not affect the efficiency of the system. The defoamer should last until the next time you drain and refill the reservoir. You can get more from your local hardware store. Here is a link to more information on this important ingredient: Cell Production, Important Data. Go to the bottom of the page for more information on where to find it.

In freezing climates you may want to add some additional KOH to your mix. KOH lowers the freezing point of water considerably. Your system may run at a much lower duty cycle and may be a bit less efficient. But that's better than having your system freeze and not be able to use it at all. If you put in 31% KOH (by weight), your electrolyte will not freeze until it gets below -65 C (-85 F) degrees F. Most climates won't require more than 28% which is good down to -40 C (-40 F). For other temperatures and concentrations see KOH Freezing Temps.

When filling the Reservoir, keep the electrolyte at least 3" from the top. If you drive on bumpy roads you may want to hold the electrolyte level even lower. This is so electrolyte will not get into the HHO gas output hose and fill up your dryers, or go on toward the engine. Refill the electrolyte before the level gets to within 1-2" from the bottom. To replenish the electrolyte, add distilled water only. After many refills, you may find you need to add a bit of KOH to keep the amperage up.

Once per year, you should drain all of the electrolyte from the system and replenish it with all new water and KOH.

To obtain additional potassium hydroxide its best to use a specialty supplier. If you live in the U.S., we recommend getting it from They sell a 2 lb bottle for $7.95 that should last you for a year or so, depending on the amount of driving you do. We sell one pound bottles for your convenience, but we can't supply this material for the prices that specialty places can. If you live in a country other than the U.S., you will need to find a local supplier, because we can't ship KOH internationally. Importing KOH requires more paperwork than it's worth. Just find a local soap making supply company and they can sell you KOH flakes. You can also google on soap making supplies in your country.

4. Install the PWM

Before diving into an installation and operation of your PWM, it is advisable to find out what a PWM is and how it does it's job. There is a simple article on the site that will walk you through the basics of a PWM, and clear up the terms that are used in conjunction with it. Including what "PWM" actually means. You can find it here: What Is A PWM?

Main Components

  1. The LCD Display/Controller module. This device shows you the important readings of your PWM, and also controls the PWM so that it maintains its constant current maximum amperage. This device should be mounted in the passenger compartment of your vehicle so you can see at a glance what is going on with your HHO system.
  2. The PWM enclosed in the green heat-sink case. This is the actual PWM that does the work of pulsing the power to an HHO cell. This device should be mounted near your cell to minimize the length of any wire runs between your battery and the cell.

The LCD display only needs to be connected to the Cat5 cable coming out of the PWM. Plug the Cat5 cable into the receptacle in the Display. It gets its power through this cable. You can then secure the back of the display with the 4 screws provided.

While you are initially setting up your HHO system, it is handy to have the display near your system so you can easily monitor your system when you first start it up. Later, when you have everything working properly, you will want to run the Cat5 cable into your passenger compartment and permanently mount the display where you can see it. Note: to disconnect the Cat5 cable from the Controller's terminal, carefully insert a small screwdriver underneath the cable and press up to disengage the locking tab on the connector.

Connect your PWM to the cell and battery. There are 4 terminals on the back of the PWM for this purpose. Batt+ and Batt- go to your battery. Use heavy gauge cables for these runs. Red is for Batt+ and Black is for Batt-. Be sure to use a wire gauge that is suitable for the amount of amps you are planning to use, and the distance you must run the wires. If you are mounting your PWM closer to the battery, you can use smaller gauge cable. We recommend a minimum of 10 gauge. HHO+ and HHO- is for the cable connections to your cell. These should be of the same gauge that you ran to the battery as they will carry an equal amount of current.

100A PWM

Our cells are provided with different numbers of plates. These start out with 5 neutral plates and 2 hot plates (plates that get a connection to the PWM), and we call this a single stack configuration. The single stack has 7 plates total. Each time we add an additional hot plate and 5 neutral plates, we call this another stack. A double stack has 13 plates, and a quad stack has 25 plates. The double stack is the most common configuration.

When using 24 volts, the cell is connected differently than when used with 12 volts. For 12 volt operation, we want 5 neutral plates between each hot plate. But for 24 volt operation, we want 11 neutral plates. Therefore, we don't connect all of the hot plates when wiring for a 24 volt system. The following diagram will show the different wiring configurations. Note that the white and green wires are interchangeable. Just note the spacing of the connections.

Cell Wiring Connections

IMPORTANT SAFETY RELATED INFORMATION: Once you plug in the Cat 5 cable from the controller, the PWM is now all connected, but still will not work. It still needs voltage to it's controls circuit in order to turn the PWM on. You will find the control wire connection at the removable green terminal block. It is labeled, "12/24/32 Volts In". You'll need to provide power to this terminal when you want the system to operate. This wire should be connected to a circuit such as the fuel pump relay circuit, or other circuit that is only on when the engine is running. This is to ensure that the PWM is not running when the switch is on, but the engine is not actually running. Be sure to test this circuit carefully to make sure it is only on when the engine is running. If your HHO system is producing HHO while you are sitting in your truck listening to the stereo, you can have HHO build up under your hood, and this can explode when you start your engine. So this point is vitally important.

Once the control wire is connected, you can turn on the PWM by turning on the power switch on the PWM. For normal operation, you would leave this switch in the "On" position, and turn the system on and off by supplying (or not supplying) voltage to the control wire. If for some reason, you are unable to find a circuit that comes on only when the engine is running, you can still control the PWM via voltage sensing by the controller, described later in this document. Voltage sensing is a way for the PWM to sense when the alternator is turning and supplying voltage to the electrical system. In this case the PWM will only run when it senses the higher voltage supplied by the alternator. We recommend using both methods for the best safety.

At the end of this document, you'll find the instructions for programming the PWM, including voltage sensing. However, the steps above will be enough to the get PWM working and making HHO gas. If you want to test the HHO gas production, be sure to have your engine running. Running the system on the battery alone will not only quickly discharge your battery, but will also not allow the system to come up to full amperage due to the lower voltage of the electrical system when the engine isn't running.

5. Install Your Electronic Enhancement

Many commercial tier 1-4 truck engines will get excellent mileage gains by using the HHO without any electronic sensor enhancement. They will most certainly get a drastic reduction in pollutants, and an increase in horsepower. But you should also be getting a significant increase in fuel mileage. If you are not, you will need to add an electronic sensor enhancer. We include a device that is appropriate for your vehicle as part of the kit.

For diesel engines, we include a MAP/MAF Enhancer for this purpose. For gas engines, we include an EFIE. We designed and manufacture these electronics at The instructions for installing them are posted here: Installation Instructions. If you need help with the install of these devices, please contact tech support at: We also strongly recommend the Documents Page. It has a wealth of general information about HHO systems, and vehicle electronics that will help you succeed with your installation.

6. Initializing the system

Now you can start the system and begin making gas. Sometimes the system won't start because the electrolyte didn't go by the check valve and actually fill the cell. When this happens you'll have very low or no amperage. You can fix this by opening the drain cap and letting the air out of the hose. Use rubber gloves for this so you can avoid getting KOH on your skin. But this should get the electrolyte to flow into the cell and it can start making gas.

Once your gas production is going, it's a good idea to check all hose connections for leaks by applying soapy water using a spray bottle. If there is a leak, bubbles will be immediately evident. Repair all leaks. Also note, that failure to screw down the lid to the reservoir properly can allow your HHO gas to escape around the cap. Make it a point to always screw down that lid firmly. Also check for electrolyte leaks by visual inspection after it has run for a while.

Watch the display and you will see the amperage climb up to the amperage set point. Once the amperage comes up to it's set point, it will not go higher. But you'll notice that the duty cycle percentage starts to go lower. This is the PWM controlling the output amperage to maintain its set point. If the duty cycle drops too far, like below 50% or so, then you'll want to dilute your electrolyte. If the amperage never reaches the set point, you'll want to add more KOH.

If you have gotten to this point, but your amperage hasn't come up to the set point, you'll need to add more KOH. Before adding KOH, be sure that the electrolyte has actually gotten into the cell. If it has, you will see a steady flow of electrolyte and HHO gas coming out of the cell output hose and going into the reservoir. Lack of any flow is almost always caused by vapor lock in the tubing, where an air bubble is preventing the electrolyte from getting into the cell. In this case you must bleed the air out of the tubing to get the electrolyte flow started. The only other causes of no flow are: 1) No voltage being supplied to the cell, and 2) No electrolyte in the water.

Once your cell is basically operating, you may want to adjust your electrolyte concentration. I usually like to have my electrolyte be strong enough to come up to my target amperage when the engine is cold, but not so strong that the PWM has to start reducing the duty cycle. That way as the system warms up, the amperage the duty cycle will remain fairly high. If the duty cycle is getting too low during operation - such as running below 25% - then you are not going to be getting the best efficiency out of your system. Dilute the electrolyte by adding more distilled water. Note, if you don't understand the terms in this paragraph, please see What Is A PWM?.

If everything is OK up to this point, you are ready to start operating your cell for mileage gains. This is done in 2 ways:

  1. Making adjustments to your PWM Amperage setting. There will be a sweet spot where you will get the best mileage. It is a common misunderstanding where people think that more HHO will give better mileage gains. THIS IS NOT TRUE. We have seen many apparently failed installations get completely turned around be REDUCING the amperage and HHO, often by 50% or more. As a starting point, you should run your 15L truck engine at 25 amps. Be prepared to go lower however, just as likely as to go higher to find the best mileage. Once you have found the best amperage setting for your engine, then you can go on to your enhancer adjustments.
  2. You may not need any electronic enhancer because you may be getting the expected mileage gains without it. But if you do need one, then the next step is to make adjustments to it as covered in the installation instructions for the device you are using. You will make adjustments between each gas fill up, until you have reached the best possible mileage gains.

Big truck engines should be able to achieve a 15% mileage improvement without much trouble. If you have mileage results that fall below that, we consider you have a failed system and it's in need of some debug. We have customers that have gotten 35% gains and even more. We feel that 20% is a reasonable expectation. If you are not getting gains like this then something is wrong with your installation, and if the problem is found and handled, you'll get the gains you are looking for.

Note: If you have used HHO systems on a car, you may be accustomed to higher mileage gains. That's because cars start out running less efficiently than most big rig trucks. There are more gains to be had in many passenger cars and pickup trucks. We expect to get 35% on a car, and gains of 50% and even 100% are not that uncommon. But we don't generally see gains that large on tier 3 trucks. An improvement of 15-20% on a Tier 3, Semi tractor trailer rig is a good target for a successful installation.

Controller Programming

To program the PWM, we use the knob below the Liquid Crystal Display. Press the knob once to enter setup. Now you can turn the knob to cycle through the different functions. When you get to the function you want to change, press the knob again, and you'll enter that setup screen.

To make the changes, you will use the knob and button. Use the knob to navigate through any options available, and then press the knob once to select the new setting. Some screens have multiple settings, and you turn the knob to make any needed changes, and press the knob to accept each setting. Finally, turn the knob to the final screen that is labeled, "Exit", and press the knob once more to resume normal use of the system.

Here's the full listing of the Menu Items:

1. PWM Constant Amps: Use this screen to set the PWM's amps. The amount you should set for different engine sizes can vary, but for 15L engines we usually run the system at 25 amps. No matter what setting you use, you'll need to try different amounts of amps to find the best improvement in mileage for your particular engine. You can see this article for more information. How Much HHO Should I Use?

2. Volt Sensing: This item has several settings. The first is "Y" or "N", and sets whether volt sensing is activated. If not activated, the system will not shut down on low voltages, and will only shut down if turned off by the switch or if power is removed from the control wire. If "Y" is selected then the next 2 screens will allow you to adjust the "On" and "Off" voltages. The On Voltage is the voltage that must be available in order for the PWM to turn on. Then, if the voltage drops below the Off Voltage, the PWM will shut down. In that case, the voltage must come back up to the On Voltage again in order for it to start back up. When this happens, an error is reported at the display to alert the operator.

To get reasonable voltages for use on your system, you should power up the PWM with the engine not running, and note the voltage on the display. Add about .25 (one-quarter) volt to that amount and use that as your "Off Voltage". Then turn the engine on, and note the voltage when it's running. Subtract about .25 volts from that amount, and make that your "On Voltage".

3. Level Alarm: This function causes the display to sound and show an alarm when the level in your reservoir gets too low. It requires that you have a float switch for your reservoir installed. We include one of these in your reservoir. To activate it, you must change the setting from "N" to "Y". You would also select the type of switch that you have - normally open or normally closed. We ship out the reservoir with the float switch in the "Normally Open" position. However, you can rotate the float switch so that it is upside down and it will then be "Normally Closed". You might wish to do this if don't want to be alerted until the tank is closer to being empty.

Wiring the float switch: You must connect the float switch to the PWM's green removable terminal block. Connect the wires to terminals 3 and 4, which are marked "Float Switch" and "Float Switch (Gnd)". Extend the wires from the float switch as necessary with any gauge wire you have handy.

4. Enter Codes: This is used to enter codes that affect the operation of the PWM. Don't use this function unless directed to by support personnel. If you accidentally get into this function, just press the button twice to exit the function.

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