Water management

Reading time 5 minutes

Updated – December 31, 2022

Water procurement, water management, a frequently vexing topic for mobile home owners. On the one hand, it seems difficult to get drinking water, but on the other hand, consumption patterns often reach the relatively narrow capacity limits of the installed water tanks.

This gave birth to the idea of recording and visualizing drinking water consumption. This in turn gave rise to the idea of more or less automating the filling with drinking water. If the consumption has been recorded since the tank was completely filled, you not only know how much water was used, but also how much needs to be refilled. And this without flooding due to overflowing filler necks, etc.

A water meter like at home was ruled out for size and weight reasons. It should be digital, reliable, clear and easy to use. This is how the one operated with 12 V DC was found Water flow meter with digital display of consumption in liters, flow rate per minute and temperature in C°, including Hall sensor, temperature sensor, 12 V DC solenoid valve and 230 V AC plug-in power supply.

ps This measure offers the opportunity to install a manual shut-off valve in the water hose coming from the water tank!

Consumption measurement

The Hall sensor has 1/2″ external thread (AG), both of which are provided with a reduction from 1/2″ internal thread (IG) to 3/4″ AG. Make sure that the reduction has a rubber seal on the 1/2″ female side (true to the motto “two is better”).
The anaerobically setting, gap-filling Petec is applied all around on two threads of the 1/2″ AG. The reduction is then screwed on. The connection is immediately waterproof.

An angle hose screw connection 3/4″ to 1/2″ hose nozzle (corresponding to the hose diameter installed on the water pump) is screwed onto the 3/4″ male thread. Here too, ensure that the rubber seal is seated correctly.

Before installation, the plug of the Hall sensor must be cut off, the ends stripped to about 4 mm and tinned. A five-wire cable (if the temperature sensor is not needed, a three-wire cable is sufficient) is stripped of its insulation by approximately 8 cm. The ends are again stripped of insulation by about 4 mm and tinned. Heat shrink tubing is pulled over the 8 cm ends to insulate the solder connections. Another shrink tube is pulled over every three or five wires to ensure greater stability.
Unfortunately, the manufacturer did not choose the same wire colors for the connection cable to the controller as for the sensors. Therefore, note the colors on the cut socket part of the sensor and assign the colors on the connecting cable accordingly. Now also cut off the three-wire plug, strip about 4 mm of insulation from the cable ends, tin them and solder them together in the correct order.

Now push the three thinner shrink tubes in the middle over the soldering points and shrink them using a heat gun. Finally, position the larger shrink tube so that it still covers the beginning of the cable jacket and shrink it.
If the temperature sensor is installed, the connections are handled in the same way.

This unit is now inserted into the hose on the suction side of the water pump and fixed over one of the reductions using a suitable hose clamp. In this way, the sensor remains constantly depressurized even with pressurized water pumps. There is an arrow on the back of the Hall sensor that indicates the direction of flow. The tank line is connected on the input side and the pump input line is connected on the output side.

The three or five-wire cable now needs to be laid to the location where the controller with the digital display is to be mounted. The cable length is not critical up to 10 m. A two-wire 12 V DC cable must also be laid to the controller.

Laying the cable is the most time-consuming part of the campaign. Ideally, you should connect a 3 A fuse to the positive line, either a flying fuse or a clearer one Fuse panel.

The controller can be attached using double-sided adhesive tape on the back, making it easy to dismantle and replace if in doubt.

Operating the controller is quite simple. One press of the button Run/Stop switches on the measuring unit, the controller LED lights up green. Pressing this button again turns off the green LED and turns on the red LED; the measuring unit is switched off. When measuring consumption, the green LED remains constantly active.

The measured values are reset after selecting the respective value by pressing the button several times Menu and then holding the button Clear for longer than 3 seconds until the beep.

Setting the K value is only necessary when replacing the Hall sensor. Every Hall sensor comes with a data sheet showing the K value.

The temperature of the temperature sensors is permanently displayed.

Fill quantity measurement – and automatic water stop

This is where the controller’s solenoid valve function comes into play.

If you know that 118 liters have been consumed according to the digital display, you set the filling quantity preselection on the controller to these liters, connect the filling hose, open the tap and press the button Run/Stop on the controller. The solenoid valve ultimately opens and closes automatically when the set counter reading is reached.

Before you can enjoy this convenience, you need a second water flow meter as described above.

The structure is as follows: Gardena tap connection 3/4″ with large flow -> reducer 3/4″ male to 1/2″ female -> 1/ 2″ male solenoid valve connection -> double-sided 1/ 2″ female socket -> 1/ 2″ male Hall sensor connection -> Gardena tap connection 3/4″ with large flow -> reduction 3/4″ male to 1″ female in the HT blind plug -> water tank.

Depending on the installation situation, suitable angle pieces may be required.

On the Niessmann Flair here, the water filler neck is connected to an HT pipe DN40. An HT Y-branch was inserted, the branching connection of which was closed with a blind plug. A hole was made in this blind plug to accommodate a reduction from 3/4″ male to 1″ female. A Gardena tap connection with a large flow is screwed onto the AG and fitted with a drinking water hose. This leads to an additional built-in flap with a lock, through which a water hose with a Gardena plug-in system can be connected from the outside.

During filling, the water is guided via the solenoid valve, which is switched on until the set water quantity is reached, and the subsequent Hall sensor that detects the water quantity, via the reduction installed in the DN40 HT blind plug and into the water tank.

To set the desired filling quantity, briefly press the button Menu the menu item Quantitative called up and with a long press of the button SET confirmed until the corresponding value flashes and a beep is emitted.
With the Arrow UP/DOWNThe respective position is set using the buttons and briefly pressing the button SET taken over and moved to the next position.
Once the value has been completely entered, the value is changed by briefly pressing the button menu saved and exit the menu.

Pressing the RUN/STOP button opens the solenoid valve. Once the set filling value is reached, the valve closes automatically.

remote control

You may want to have the RUN/STOP button available on the outside of the water filler neck. For this purpose, the housing can be opened and a two-wire cable soldered parallel to the button on the controller (attention: loss of warranty). The new Button (with red or green ring LED) is conveniently mounted in the supply flap.

Since the socket is 7-pin (3 for the Hall sensor, 2 for the solenoid valve and 2 for the temperature sensor), but the temperature sensor is rarely integrated into the water pipe, the two temperature sensor cables can be separated.

To avoid an error message regarding the missing temperature sensor, connect its connections directly to the soldering points on the circuit board. Using a drill suitable for an M8 thread, a hole for the temperature sensor can be drilled next to the connection socket and the same can be screwed in there from the inside.

The now free cable ends of the connection socket are extended and the ends are soldered to the right and left connections of the internal run-stop button.

It is possible to control the LED located in the externally installed button via the relay connection in the water inlet, which is already nearby. This means that the switching status can be visually checked inside and outside at any time.