Irrigation Pump Timer with Low Voltage Disconnect

Pictured below is a device we made to control the pump of an automatic and often unattended irrigation system which is solar powered.

irrigation system pump control timer with low voltage disconnectprogrammable digital timer is set with the times that the pump is to be run – typically very early in the morning and in the evening. The pump for this particular irrigation system is relatively high powered, so could not be switched directly by the timer. Therefore a 10A rated relay is built into the controller.

As this system is solar powered and also often left unattended, it was essential to include a low voltage disconnect which will automatically prevent the pump from running whenever the measured battery voltage is found to be <11.9V. It then waits until the battery has been charged back up to over 12.5V before allowing the pump to run again.

LED indicators are included to show when the programmable timer is ON, the status of the low voltage disconnect, and also the status of the pump switching relay.

If you need any kind of irrigation pump timer or controller please email with details of your requirements.

Automatic Irrigation System Timer Controller

Pictured below is a timer controller we recently made for a commercial irrigation system. This set up currently has four solenoid valves which when opened, water different regions in a large greenhouse. The number of solenoid valves will soon be increased to eight, so we had to make this controller work now with four valves, but be ready to control eight in the future. The controller is based around an Arduino Pro Mini.

automatic irrigation timer controller

The main controller board above drives four or eight of the 10 Amp rated relays on the relay board pictured below.relay board for irrigation timer controller

The small button at the top left of the main controller board can be used to toggle between four valve or eight valve operation as per the user’s requirements.

The valves are to be opened on a four hour cycle. With four valves, each valve is opened for 15 minutes in turn with a 15 minute delay between. Then after a two hour delay, the cycle repeats. With eight valves, each valve is opened in turn for 15 minutes with a 15 minute delay between each. The cycle then immediately repeats.

If you need an automatic timer controller for an irrigation system, please email with details of your exact requirements.

Rainwater Toilet Flush Pump Controller with Overrun Protection

We make a wide selection of rainwater toilet flush pump controllers for domestic use, and pictured below is another of these.

Rainwater toilet flush pump controllerThis particular controller is designed to be used where there is a very large amount of rainwater storage and a relatively small header tank. In this scenario, if the float switch which detects whether the header tank is full were ever to fail or get jammed with debris etc, 1000’s of litres of stored rainwater could be pumped out through the header tank overflow and lost.

In this controller, the user can programme in a maximum pump running time. If the pump ever runs for longer than that time, it will automatically be turned off, and will not turn on again until there has been manual intervention from the user (checking over everything and resetting the controller).

In standard operation, the controller simply checks the status of the header tank float switch located just below the tank overflow outlet, and shows this status with an LED indicator. Once every four hours, the controller tops up the header tank by turning on the pump and running it until the header tank is detected to to be full.

If you need any kind of pump controller, please contact with details of your exact requirements.

Automatic Pump Timeout Circuit

Picture below is an automatic timeout circuit we recently made for a rainwater collection system.

rainwater pump timeout circuitThis is for use within a rainwater toilet flushing system with 3000 litres of rainwater storage capacity and a standard header tank in the loft with a ballcock. The pump is a 12V pressure activated pump of the type common in motorhomes and boats. As the toilets are flushed, the ballcock drops in the loft tank and the pump automatically switches on to refill the tank with water from storage butts in the garden.

If the rainwater supply runs out then the pump will run dry okay, but if it is left running dry for too long it will burn out. Therefore a device was required which would automatically cut the power to the pump if it was detected as having run for too long – more than five minutes. (It was not possible to use float switches to detect low water levels in the water storage vessels due to their location).

Handily the chosen pump outputs a 12V signal while it is running, so this can be used to monitor the status of the pump without the need to detect the increased current draw through the cables when the pump is running or the sudden dip in battery voltage when the pump switches on etc.

The device we made is fitted with a 10A rated relay with NC and COM connections – therefore when the relay is not energised, NC and COM are shorted out inside the relay and the pump receives power. When the relay is energised, NC and COM are open and so the pump receives no power.

When the pump is detected to have started running, a timer starts. If this timer gets to five minutes then the relay is energised cutting the power to the pump to save it from burning out. An LED is used to let the user know that this has happened and they system has to be powered off and then on again to reset it after the pump has been checked and the water stores replenished.

As the rainwater storage is also sometimes used to water gardens from a connected tap, the device also has a manual override. Pressing and holding the button for one second triggers the override and then the pump can be run for as long as the user wants until the override is cancelled with the button.

If you require any kind of rainwater pump and/or monitoring system, email with details of your requirements.

Header Tank Filling Pump Controller

Pictured below is a controller we have just finished for a customer. We make a lot of rainwater toilet flush pump controllers, but this one is a little different from the norm.

Automatic header tank filling pump controller with time delay and use programmingThis controller is for a pump with its own integrated run-dry float switch protection. A second float switch is located in the header tank. When the header tank float switch goes low (as the water level drops), a user programmable (1 to 99 minutes) timer starts a countdown. When the timer has elapsed, the pump is switched on with the on board relay, and is run until the float switch goes high on the increasing water level.

This version will work well for situations in which water is taken regularly from the header tank, and in particular in situations in which water will be taken from the header tank a few times typically during the timer countdown after the water level first used – e.g. multiple people coming home at the same time and all using the toilet.

The advantage of this system is that only one float switch is needed in the header tank (and there is no need to estimate the time taken to fill the tank by the pump etc).

The disadvantage of this system is that sometimes when the header tank is not being used, the water level will drop because of evaporative losses or leaks in the pipework etc. To mitigate against this, we set up the controller to run the pump for a minimum of 30 seconds each time it is turned on, and also to require one continuous second of changed float switch condition before any action is taken so that turbulence is ignored and to avoid multi-switching (which could rapidly damage the pump).

If you need a pump controller for your well, sump, rainwater toilet flushing, etc, then please email with details of your exact requirements.


Rainwater Toilet Flush Pump Controllers with LCD

We have been making a bespoke range of controllers for people who would like to use rainwater for their toilet flushes for around 6-7 years now. Here is an example of one of our early Rainwater Toilet Flush System Controllers with details of how such a system works.

rainwater pump controller with LCD display and empty water butt sleep functionPictured above is one of our more advanced systems which includes an LCD display to keep the user up to date with the status of the system and water levels in the water butt and header tank (which gravity feeds to the toilet cisterns in the home).

In this particular case, if the two float switches in the header tank are not in water, the tank is empty, and so the pump turns on to fill the tank. If there is sufficient water in the water butt to fill the tank, then the pump will stop when the tank is detected to be full. If however the water butt is empty (or becomes empty during pumping), then then controller sleeps for four hours to allow a rain shower to collect a good amount of rainwater (if it rains in the meantime) so that pumping later will fill the tank.

rainwater controller system normal LCD displayThe display constantly shows the status of the water butt (WB) – either OK or LOW (empty), and the status of the header tank (HT) – either EMPTY, OK, or FULL. The bottom line of the display shows whether the pump is running, the controller is sleeping, or everything is just ticking along as it should.

rainwater pump controller with mains water solenoid and LCD displayThe controller pictured above is a little more advanced. If the header tank is detected to be empty, then the pump will start as normal unless the water butt is also empty. If during pumping, the water butt becomes empty (or if it is already empty when the header tank is detected to be empty), a solenoid valve will close which will allow the flow of water up the rising main to enter the header tank to ensure that the toilets can always be flushed without any manual intervention.

rainwater controller with solenoid valve activatedThe display for this particular controller also shows the user when the solenoid valve is open so they know that you are using mains water due to a lack of stored rainwater in the water butt. There is no need for a four hour delay with this unit since every time the header tank empties and the water butt is either empty or becomes empty during pumping, the mains water supply will top up the header tank.

This controller is based around an Arduino Pro Mini microcontroller development board and uses standard horizontal float switches in the water butt and header tank to detect water levels.

If you need a rainwater toilet pump controller of any type, please email with details of your specific requirements.

Automatic Irrigation System with Moisture Probes

Pictured below is a controller we recently made to automate watering of plants depending on the moisture level of the soil in which they are growing.

Automatic irrigation controller with moisture sensing probes

This device measures the resistance between two stainless steel probes made from 1.6mm arc welding rods (pictured below) to which leads have been soldered, and inserted into the soil a few centimetres apart. When the soil is measured to be ‘dry’, a pump is turned on which waters the soil. When the soil is subsequently measured to be ‘wet’, the pump is turned off, but only if it has already run for a user programmable number of minutes first.

Stainless steel welding rods used as moisture sensors

To provide default wet and dry thresholds, the resistance between the probes was measured at what the user considered to be the dry and the wet threshold. These values were 36.5 kOhms or lower for wet, and 229 kOhms or higher for dry (with the probes inserted 7cm into the soil, 6cm apart). Therefore we programmed the controller to turn on the pump after 5 continuous seconds of resistance measured to be below 36.5 kOhms, and turn off after 5 continuous second of resistance measured to be above 229 kOhms.

Since different growing mediums may be used in the future, we also made this controller so that the user can calibrate the wet and dry thresholds themselves or revert to the default values.  Calibration is achieved simply by putting the probes into soil which the user considers to be at the wet or dry threshold, and pressing a button to save the measured resistance value in memory as the new threshold.

If you need an irrigation controller similar to this, please email with details of your exact requirements.

Rainwater Pump Controller – Anti-Interference Modifications

Pictured below is one of our rainwater toilet flush pump controller units which we have had to modify to overcome a problem with interference.

rainwater toilet pump controller programmed to cope with interference in long float switch cablesThe customer had a problem with the original unit we supplied due to the length of the cables running to the float switch in the header tank – more than 10 metres. This controller is designed to check the status of a float switch at the top of a header tank every two hours. If the header tank is found to not be full then the pump is turned on until it is full, pumping water from a water butt at ground level up to the header tank which gravity feeds the toilets.

The way we had programmed the original unit, the float switch had to remain high on the full water level continuously for one second before the pump would be switched off. Unfortunately during that one second of multiple measurements, at least one measurement was getting scrambled by interference resulting in the pump staying on continuously.

For the new modified unit, the controller tests the status of the float switch 10 times every half a second, and if more than seven of those readings are high, the controller will turn off the pump.

There are ways that we could have suppressed the interference problem with modifications to the hardware, but as we could not test the controller on site we chose a software method which we have found to work well previously – particularly in Eastern and Southern Europe where they seem to have more interference problems than here in the UK.

Project of the Day – Automatic Toilet Flush Counter

This week we have been working on a project for a toilet manufacturer making a device which will count and log the number of times a toilet is flushed or partially flushed.

Although flow meters are already in place to measure the exact volume of water consumed by the toilets being tested, the key metric to calculate accurately is the amount of water used per flush, and to obtain that information it is essential to also count the number of times the toilet has been flushed.

There is no easy direct way to detect whether a full or partial flush has occurred, so two float switches have to be inserted into the toilet cistern – one just below the full cistern depth and the other just above the cistern depth immediately after a full flush.

automatic counter to log and display the number of times a toilet is flushed

When the level of water in the cistern drops below full (indicated by the upper float switch going low), we know that a flush has begun. Typically a full flush will take around 5-10 seconds at most to empty the cistern into the bowl (at which point the lower float switch will go low). Our system waits for up to 15 seconds to see if a flush is a full flush. If during that time the lower of the two float switches does not go low, it knows that a partial flush occurred.

This flush is then added to the relevant counter – full or partial – and displayed. The system then waits for the cistern to fill up again, and when upper float switch goes high it re-arms the flush detector ready to detect the next flush.