Watchman Sonic Advanced Installation Instructions

Have you recently purchased a Watchman Sonic Advanced and unsure how to install it onto your oil tank? Here at we can provide you with an easy step by step guide to help you correctly install your Watchman Sonic on to your tank.


How do I install the Watchman Sonic Advanced?

To ensure a quick and easy installation of the Watchman Sonic Advanced, please follow the below steps.

Parts required for installation


Step 1 – Checking tank’s level, distance from receiver and height of tank.

There a few things to consider, even before you start to install your Watchman Sonic Advanced onto your tank.

  1. Is the tank on a flat level surface?
  2. Is the tank within 200 meters range from the receiver position?
  3. Not including the base, is the  maximum height of the tank 3 meters?  If larger than this, please contact us.
  4. Tank must be fitted in accordance with manufacturers guidelines & instructions.

NB: Any radio frequency signal may be seriously inhibited if positioned underground. Please check that the transmitter/ receiver link works in the desired location before installation.

Step 2 – Preparing your tank

Below are few steps for making sure your tank is ready for the Watchman Sonic Advanced, whether you have a Pr-Drilled tank or one which is undrilled, we have a step for you.

Please note that it is important for all items to be kept dry during the installation process, to achieve the best outcome.

Pre-Drilled Tanks

Option 1: There may already be a 32mm pre-drilled opening in the tank top and possibly a tube fitted. If so, remove the cover by undoing the two screws holding it in place, and dispose of the tube in accordance with local government guidelines.

Option 2: There may already be a 2” threaded hole with a red cap screwed in to it  If so remove the red cap and disregard.

NB - Ensure the hole is a minimum DIAMETER 30mm. Ensure that the space beneath the Watchman Sonic unit is free of any obstacles and that the ultrasonic beam path is clear of obstructions. (See Picture 2)

Un-Drilled Tanks

Where drilling is required to fit the transmitter, choose a flat level point that is at the same level and no lower than any opening at the top of the tank (filling point etc.)

WARNING: If you are unsure if you should drill a tank please check with the tank manufacturer first.

Take care not to choose an area where water could gather, i.e. a dent/depression or a position directly above any restricted area, as this can again give a false reading.

If your Un-drilled tank has window configurations or internal braces (like the below image), please do not position your watchman Sonic directly above these or within 15cm of the area of the window or edge of the tank. The sonic’s path needs to be completely clear to the bottom of the tank to work accurately.

NB: For tanks with window corrugations or internal braces ensure that the Watchman Sonic Advanced is not positioned above or within 15cm of the area of the WINDOW or the edge of the tank. If the Watchman Sonic Advanced is positioned over or close to the WINDOWED area it transmits incorrect readings to the receiver. (See Picture 5) Ensure that the sonic path is clear to the bottom of the tank as per pic 2. When installed incorrectly on some windowed tanks the unit can experience false alarms as the oil level drops. It is important to ensure that the unit is positioned so that the ultrasonic beam has a 30cm diameter clear area to the bottom of the tank. Positioning the unit too close to the tank wall or near a tank window may cause false alarms.

Once you have found the correct position, drill a hole in the tanks top surface, using a 32mm hole-saw.

Warning: If you are unsure if you should drill the tank please check with the tank manufacturer first.

Step 3 – Fitting the Transmitter

For tanks with pre-drilled holes. Ensure guidelines from points 5 & 6 are adhered to.

  • Remove cap from the hole (Picture 7) and insert  transmitter base, ensuring the weather seal is securely  in place (Picture 8 & 9).
  • Tighten the Watchman Sonic Advanced base (Part E) on to   the tank with 2 stainless steel self-tapping, counter sunkscrews  supplied (Part C). Do not over tighten!

Step 4 - Fitting the Bund Sensor (Optional)

Having followed the steps 1 to 3 in the instructions the WatchmanSonic Plus transmitter should be fitted on the inner tank. The leak detector should hang 5cm above the bottom of the outer tank in the interstitial space of the outer tank as shown on the picture above. To avoid the leak detector resting on the bottom of the tank, adjust the cable length using a cable tie provided. Note: It is imperative that the leak sensor is positioned vertically above the floor on the inner tank and that the cable is fixed to avoid any slippage or lengthening of the cable. Length of the cable can be adjusted using the cable tie provided.

Step 5 – Define the Sonic Height

To accurately measure the height of your oil tank, measure from the base of the tank (not including the base/piers the tank is positioned on) to the position of the Watchman Sonic (should be the same as the fill point). For the Watchman Sonic Advanced to work, the maximum height is 3 meters for the measurement above.

Height does not include the base/piers which tank sits on.

Step 6 – Setting the Switches on the receiver

Within your product packaging, use the Tank height chart, read across to the relevant multi switch setting, using the tank measurements you took in step 4. For example, if your measurement was 100cms, then the switches to flick up would be Switch 5 and switch 7.

To flick the switch upwards, using a screwdriver or top of ballpoint pen to set the relevant switches. These switches can be found on the on the back of the received above the plug (as in the position displayed below)

NOTE: If switch 1 is ON, it enables Sudden drop alarm. This functionality is valid only when used with advanced transmitters.  If switch 2 is ON, it enables Waveguide mode, this functionality  is valid only when used with advanced sonic transmitters.

Switches 1 & 2 are factory set switches and have no relevance to the end user. If you wish to set a audible ring feature, then switch one needs to be moved up. This will cause the the unit to bleep in the event of a low level reading.


The Sonic Advanced transmitter on tank checks the oil level approximately once every minute. Under normal conditions it communicates this level to the receiver approximately once every half hour. In the event that a level outside the predefined threshold trigger level is reached in a given period (approximately 1.5cm per hour)  the on tank transmitter sends a signal to the receiver and an alarm will be set off on the receiver unit. In alarm mode the receiver unit will emit a siren type sound and the 10 bars will appear on the screen in sequence. The red LED will also flash. This can only be reset by plugging in and out the receiver unit from the mains. The maximum permissible usage of oil that the unit will allow in height terms is 1.5cm per hour. This is the maximum rate that the level can drop in one hour without the alarm going off. WARNING:- Alarm and level functionality will be disabled if the unit detects a no echo condition (ref: section 11 - Technical Information). The no echo condition is indicated by a triangle symbol in the centre of the screen with a line to the right of it. The no echo condition can be caused by the unit being incorrectly installed on the tank, alternatively it can indicate in some instances that the unit has been moved or removed from the tank. An audible alarm can alert the user that a no echo condition or a transmission not heard condition has occurred (Refer to trouble shooting for explanation of these conditions). Please note this is not a tamper alarm and should not be used as such.- The alarm functionality at ullage levels of less than 25cm is disabled. Therefore if a leak or theft occurs when the oil level is closer than 25cm to the Watchman Transmitter on tank unit the alarm will not go off.- In the event that the on tank unit detects a level drop there may be a delay in sending the information to the receiver. This delay is to enable validation and protect against false alarms.- This product is to be used only on domestic oil tanks within the parameters outlined in the specifications. Any use of the product on applications that lie outside a domestic environment is done so at users own risk.

Step 7 – Linking Receiver and Transmitter

You should match the receiver (Part A) with the transmitter (Part C) so that the system code is unique to your tank. Plug receiver into a suitable and convenient electrical socket and switch on. The display screen (Pic 13) on the front of the receiver will show a flashing top bar as shown in diagram. This indicates that the receiver is waiting for the unique code. The bar will continue to flash for 2 minutes during which time you can match the transmitter to the receiver.

Hold the transmitter against the receiver right hand side, as shown (Pic 14), so that the white dot on the transmitter is touching the black dot on the receiver (important!) for about 20 seconds to allow unique code to be transferred. Bars will increase up the display screen. When all 10 bars are shown they will flash to indicate that the unique code is transferred. When matched the transmitter must immediately be placed on the tank.

  • If you are installing more than one Watchman unit   please wait 15 minutes between each matching.

Step 8 – Attaching the Transmitter to the base

(A) With a base - if supplied: Screw the transmitter (Part D) into the base (Part E). Ensure the transmitter is vertical on top of the tank and level. (B) Without a Base: Screw the transmitter (Part D) and the weather seal (Part B) into the threaded hole. Ensure that the Watchman unit is screwed into the base or threaded hole (whichever applies) and that the threads have not crossed, to give a secure seal.

Step 9 - Checking the level of oil within the tank

The bar graph represents the level of oil in your tank. Note: It can take up to 2 hours for the first accurate reading from the Watchman to be displayed.

Please note that it can take up to 2 hours until the first accurate reading is dispalyed on the Watchman Sonic Advanced.

Congratulations your Watchman Sonic Advanced should now be successfully installed.


If you require any further technical information, or if your Watchman Sonic Advanced is not working as it should, please contact