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Custom truck undercarriage with gold air tank, axle, and air horns

Help Center · Air Systems

Installing The Electric Drain Valve Kit With Dual Tanks

Your electric drain valve kit will allow you to drain the moisture from your tanks from inside the cab with the push of a button.

  • Includes: stainless steel 3/8" solenoid valve (D), push button (H), 2× 3/8" NPT × 3/8" PTC elbow (A), 1× 3/8" NPT × 3/8" PTC fitting (B), 3/8" × 1/4" reducer bushing (E), 10 ft of 3/8" air line, 20 ft of 18ga wire, 3/8" PTC union tee (C), 4× 18ga butt connectors (F), and 18ga ring terminal (G)
Electric drain valve kit contents for dual tanks

Getting Started

Start by locating the solenoid valve within the kit.

1

Locate and plan the solenoid mount

This valve will need to be installed close enough to the air tanks so that we can run the air line to it from the drain ports on the tanks. The moisture will dump from the outlet side of this valve so you may want to point it down to the ground so that it isn’t spraying towards the vehicle.

Stainless steel electric drain solenoid valve
2

Install elbows in each tank’s lowest port

At this point, locate the 3/8" NPT × 3/8" PTC fittings. These fittings must be plumbed into the bottom-most port on each tank. This is not always the port in between the legs of the tank. If you mount the tank sideways, this fitting would be plumbed into one of the ports facing down to the ground.

This is essential for this kit to work, as gravity will pull the water to the bottom of the tank over time. If this fitting is mounted on the side of the tank, no water will come out when you press the button.

3/8 NPT to 3/8 PTC elbow fittings

Plumbing

Now that you have the tank portion of this install taken care of, move onto the valve.

3

Plumb fitting B into the valve inlet

You can now plumb the supplied 3/8" NPT × 3/8" PTC fitting (B) into the inlet portion of the valve. This is important because the valve is directional. If you plumb the inlet fitting to the wrong side, this valve will not hold pressure, and your tank will leak constantly.

The inlet side of the valve can be found by simply looking at the valve itself. Cast onto the valve is an arrow. The airflow needs to go in the direction that the arrow points. The arrow always points towards the outlet on the valve. Take your 3/8" NPT × 3/8" PTC fitting and plumb it into the side of the valve that faces away from the arrow.

Flow direction arrow on the drain solenoid valve
The cast arrow always points toward the outlet.
4

Tee both tanks into the valve

At this point, you can now run two lengths of 3/8" line from each tank into our tee fitting. We recommend using two 3′ sections of line for this connection. Plumb each line into tanks 1 & 2. Plumb the opposite ends of each line into the tee fitting. Tanks 1 + 2 will plumb into the sides of the tee, and the middle portion of the tee will be used to connect the tee to our valve.

Cut a section of 3/8" line to go in between the tee fitting and the valve. Plumb the line into the tee, and then into the valve at the opposite end.

Union tee connecting dual tanks to drain valve
5

Add the outlet reducer bushing

Now that the valve is in place and the line has been plumbed to it from the tanks, install the supplied 3/8" NPT × 1/4" FNPT reducer bushing (E) into the outlet portion of the valve. This will slow down the flow of air out of the valve so that you don’t lose all of your air in the tank.

At this point, you are done plumbing the electric drain valve kit, and the valve will need to be wired to the push button.
Reducer bushing for drain valve outlet

Wiring

The drain valve will be wired to a push button that can be pressed from within the cab to release the moisture from the tank. The wiring for this valve is pretty straightforward and shouldn’t take too long to finish. This valve has two leads that come off of it. It does not matter which wire you decide to use as the positive lead.

6

Ground one valve lead

Take one of the leads and route it over to the frame of the vehicle as a ground. Alternatively, you can run this to the negative terminal on the battery.

Push button for electric drain valve
7

Wire the push button to fused power

The opposite lead can be run up to one lead on the push button. Finally, take the opposite end of your push button and route it to a fused power source capable of handling a 10A load or greater. If you are installing this drain valve with one of our kits, you could simply tie it into the same fuse connected to your battery that supplies the compressor with power.

Once connected, press the button and listen for a “click” from the valve. The clicking sound indicates that it is working properly.

8

Pressurize and test

Start your vehicle and pressurize the tank. You can test this valve by pressing the button a few times and checking to ensure air escapes from it when the button is pressed.

Your electric drain valve kit is now installed and ready for use!

Next

Installing the Digital Air Pressure Gauge — prep, plumbing, wiring, switches, and mounting so you can monitor tank pressure from the cab.

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