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H2F-FM Flush Mount Water Tank Gauge Installation Guide



Fitting Recessed Display 

The LCD Polarised Display on the FM Flush Mount model is designed to be only visible when viewed from horizontal and below.    When viewed from this angle the display is extremely clear. 

  • Using the display as a template mark out hole and cut to suit

  • Fix in position with bolts provided or suitable screws

H2F FM Viewing Angle.jpg

Connecting Sender Unit  (refer diagram below)

  • The recommended installation point of the sender is 200mm after the pump

    • If you have no room after the pump, the sender can be fitted before the pump, however you need to ensure that there are no tiny pin holes, as this will allow air to enter the hose line and the water may drain back into the tank

    • If this happens it will make a machine gun noise as it is sucking in the air

    • If your receiver unit is on you may get irregular water flow as there will be no water in the sender unit but  as your vehicle is moving the sender will turn thinking that water is propelling through which may show consumption that hasn't actually occurred

    • If the sender is fitted on the pressure side any leaks become obvious


  • The thread specifications of the sender unit are 1/2" BSP male  

  • Make sure the sender is fitted with the water flow in the direction of the arrow

  • The display comes pre-wired with an approximately 1.4m sender cable  

  • Extra 1.4m & 3m extension leads are available for the three pin plugs

  • Up to 6 leads may be joined to make 9.8m in total length

  • You will need to purchase two 1/2" BSP female connectors to the size hose you have, usually 1/2" or 3/4" and two clamps.  “John Guest quick connections” also have fittings to suit their hose and the 1/2" BSP sender unit

  • Please Note:  Sender leads cannot be cut and joined – this will void your warranty, extension leads must be used

Connection to 12Volt DC Adapter


  • It is recommended that you get the 12v power from the pump circuit

  • Simply cut off the two pin 12v plug to the required length and connect the black wire to the negative terminal and the red wire to the positive power source

  • All settings and amounts will be stored if power is disconnected


Current use at 12Volt DC Adapter

  • 8 mA with the backlight LED on, only stays on for 10 seconds

  • 3 mA with the backlight LED off, goes to sleep 10 seconds after flow stops

  • 8 mA when asleep 

  • Please Note: 1,000 mA (milliamp) = 1 A (amp)

Programming Monitoring Capacity


  • Press "DISPLAY" button to turn display on

  • Next press the "PROG" button  -  "PROG" will blink on the LCD display

  • Press and release "RESET" button to choose the value of the right digit

  • Once the value has been chosen press "PROG" button to save the value -  it will then go to the next digit

  • Repeat the above procedure to program the values for the five digits from right to left

  • The first time the meter is used, fill the water tank and then use it normally until empty

  • At this point note how many usable litres the tank holds and reset the meter accordingly

  • If there is no input for one minute during the programming procedure, the programming procedure will be terminated and goes back to the original status

  • Please Note:  The maximum monitoring capacity is 99,999 litres


For Example:

  • If you have an 85 litre tank, set the display at 85 litres

  • Use normally until empty

  • If the display shows you have 10 litres left then you have a usable capacity of 75 litres

  • It is normal for tanks to hold approx 10 - 12 % less than the stated tank size.  This is because the tanks is drained from the sides, rounded corners, baffles, etc

  • Enter the usable capacity amount - in this example it would be 75 litres


  • The Topargee H2F-FM Flush Mount will automatically turn on and display the litres remaining when there is water flowing through the sensor eg a tap is turned on

  • It will automatically turn off 10 seconds after there is no water flowing

  • To manually check remaining litres, press and release “DISPLAY” button and remaining litres will be displayed for 10 seconds

End of Capacity Alert

  • The Topargee H2F-FM Flush Mount will give an audible alert and the display turns red when the remaining capacity reaches zero or minus





  • When the water tank has been refilled press "DISPLAY" button to turn display on

  • Next press the "RESET" button for six seconds

  • The "RESET" on the LCD display blinks twice and the buzzer will sound

  • The unit will then be reset to the originally programmed value

  • Please Note: You may find it easier to use the side of your fingernail or coin to hold the button in for the six seconds



To Change from Litres to Gallons or Gallons to Litres

  • Disconnect the power

  • Press and hold the “PROG” button while reconnecting the power

  • Release the button when you hear the long beep

  • The display will be switched (from litres to gallons or gallons to litres)

  • Wait until the screen turns off and the unit will store the setting​​



Fitting in Conjunction with Showermi$ers


  • If you are fitting a Topargee H2F-FM Flush Mount in conjunction with a Showermi$er, the sender needs to be fitted between the water tank and the Showermi$er return line

  • For plumbing diagram refer to the Showermi$er Installation Guide





Please Note: Due to continuous product improvement, specifications are subject to change without notice.

Downloadable Installation Guide

sender positions.jpg
H2F-FM Dimensions.jpg

Accessories for Water Gauge

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