GZF-12V Water liquid level module switch

A small 12V module that can be used to control the pump in a well or septic tank. The module can be used to fill or drain liquid.

In this article you will learn a detailed description and technical information about the module, instructions on how to connect it to the pump and also a test of liquid probes.


First, I will describe what the module is for and where you will use it.Then I will write my opinion pros and cons.

The GZF-12V module is based on the detection of the pool (water tower) to control the water level to achieve high current relay control pumping
With a small, simple wiring, low power consumption, high switching capacity, interference is strong, functional stability characteristics.
Automatically open when you can stably pool (water tower) water pump (solenoid) pumping Sheung Shui,automatically stops the pump (solenoid) when full of water.

My verdict is: GZF-12V is a useful module, the price of around 4-6 usd is good due to the design and the exact work that the module will do.Any 12V source is enough for power supply, the relay itself is galvanically separated so the module can switch other voltages as 12V e.g. 24V ,110V,220V, or other or even higher if you use a relay contactor.

Probes are enough for the test for stripping wires, in operation it is better to connect with stainless steel ends, the probes you have to make are not supplied with the product.

Use of the module:

You can use the module as a controller for a pump that fills or drains water.You can also use it to easily monitor the liquid level.You can also use it to easily monitor the liquid level the relay would switch LED lights (High-low).


  • Cheap price
  • Stable work
  • Works with DIY probes


  • Not have probes and plastic case ( this is offset by the low price )

Manual and instructions on how to connect the GZF-12 module with relay

In this section I will describe how to connect the module to the pump and probes.

Note: the relay is 10A but if you want to switch a powerful motor with consumption use a contactor or a stronger relay, solid state relay .

The output to the probes is marked as follows:

1X is the lower level

2Z is ​​medium (still (sink) immersed probe)

3S is the upper level

Use the original probes or you can make DIY them from electric wires.

Emptying the tank: If the water reaches the 3S probe, contacts 1 and 2 at the relay output will ignite (open 2-3). The water level drops below the 3S probe and only when it falls below the 1X probe do contacts 1-2 on the relay open (2-3 connections).

Filling the tank: If the water drops after the probe 1X the relay ignites 2-3 contacts (1-2 opens), the water level rises above the probe 1x and when it reaches the 3S probe the contents of the relay 2-3 open (1a2) open.

Relay terminals (module off status)


2 -COM


When the module is switched off, the following terminals 1-2 are disconnected and 2-3 are connected. The module can be used for emptying and filling the tank.

GZF-12V at work in electrical distribution box

On picture you see on the left water level switch GZF-12V and on the right power .supply 220V with DC rectification.

The power supply supplies the module with 12 volts, if you need an aliexpress, you can buy a module with an integrated 110V or 220V power supply.

The three yellow cables that go to the module are water level probes.

Below is the switching relay for the pump motor.


  • Board supply voltage: AC/DC9-12V
  • Products do not deserve the probe, do not need to buy another probe, with the home wire can replace the probe, The thread stripped about 3 cm, into the water can be directly induction
  • Can be used for fish pond water tanks, garages, underground rainwater flooding places where automatic drainage, etc.
  • PCB size:6*5cm/2.36*1.97inch
  • Relay max load 10A The relay has NO, NC, COM contacts
  • Signal LED, Red, Green.

If you have questions, write a comment thanks…

5 thoughts on “GZF-12V Water liquid level module switch”

  1. Interesting module. I bought one to try out. The electrical box you have it in is interesting as well. Where can I get one?

  2. Attachment

    This appears to be what I want this to do i.e. automatically empty a sump of water using probes to activate the pump. However I cannot seem to replicate your setup. What am I doing wrong? I think I’m not understanding the relay output and power source tho your experiment doesn’t clearly enough show how this works. Could you please clarify this for me?

  3. Attachment

    I think I’ve figured it out with the help of this other diagram found on the web.
    Although your demo was also very useful

  4. Good day can this be used for hot water and will antifreeze affect its operation. I have tried it in my water cooled generator with antifreeze added and works for a while but it seems what when it gets hot it fails and activates.
    Thank you for your time

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