Category Archives: products

Solar Water Heating Pump Controller with LCD

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Pictured below is the connection diagram for a new solar water heating pump controller we designed and built recently for use with a swimming pool heating system.

solar water heating pump controller with solid state relay and LCD and programmable timer override for swimming poolThis controller is the next step up from the solar water heating pump controller with solid state relay discussed previously. It has the same ds18b20 waterproof digital temperature sensors we use in all controllers for swimming pools and similar, but with the addition of an LCD to display measured temperatures and other system status information. (There is also a 12v digital programmable timer override function added as a specific customer request.)

LCD for solar water heating pump controller

The LCD constantly displays the temperature of the outlet from the solar thermal panel (S) and of the pool (P). It also displays the current measured temperature difference between the solar panel and pool, as well as the temperature difference required for the pump to turn on or off (as programmed by the user).

Having the LCD makes it possible to add a lot more features to this controller on request – for example keeping track of the average temperatures and peak temperatures of the pool and solar panel, tracking for how long each day the pump is running, and many other potential datalogging features.

Email neil@reuk.co.uk if you need a solar water heating pump controller with or without an LCD and datalogging with details of your exact requirements.

Arduino Solar Water Heating Pump Controller

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The REUK 2013 Solar Water Heating Pump Controller (pictured above) is one of the most popular products on the REUK.co.uk website. With a temperature sensor on the solar water heating panel, and a second on the hot water tank, this controller decides when to turn the pump on to circulate solar heated water from the panel to the tank.

This controller is based around a PICAXE-08M2 microcontroller which gives a good balance of programmability and simplicity. It does however have one large disadvantage – it can only do integer arithmetic, i.e. performing operations on whole numbers only.

Therefore when we come to make modifications to the controller for particular customer requirements – e.g. frost protection and maximum temperature shut offs etc – things get unnecessarily complicated. Additionally there is limited memory on a PICAXE-08M2 which becomes a serious problem as the complexity of the desired programming increases.

For this reason we are currently porting a lot of our PICAXE based controllers to Arduino which allows floating point arithmetic and far more memory space.

Pictured below is our latest Arduino solar water heating pump controller. It is functionally identical to the standard 2013 PICAXE controller, but offers much more flexibility for modifications and added features.

Arduino pro mini based REUK solar water heating pump controller

The Arduino board used here is the Pro Mini – the smallest of the Arduino range. The red board plugged on to the blue Arduino board in the above photograph is used to connect the Arduino to a PC via USB for programming and/or so that data can be outputted to a serial monitor in real time or for later analysis as shown below where the temperature of the solar panel and of the hot water tank is outputted once every second. If monitoring is not required then this break out board can be removed.

Serial terminal output for arduino solar water heating pump controllerIf you have any particular requirements for a solar water heating pump controller which are not met by our standard controller range, email neil@reuk.co.uk with details of what you need.

If you are interested in building and programming your own solar water heating pump controller as a project, click here for our simple Arduino Solar Water Heating Pump Controller Design and Code which should help you get started.

24V Low Voltage Disconnect with Data Display

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We have just finished working on a new low voltage disconnect project for a customer who supplies batteries and power inverters to consumers. Quite often his customers make complaints that the batteries have failed after a relatively short period of time, but he had no way of knowing if there was a problem with the battery or (more likely) a problem with the way the battery has been used and cared for.

connection diagram for 24v low voltage disconnect with LCD displayPictured above is the low voltage disconnect with datalogger we made to solve this problem.  The low voltage threshold at which the connected power inverter will be turned off, and the cancellation voltage at which it will be turned back on again can be set before installing the system. A low voltage of 22-24V is likely to be used and a cancellation of voltage of 24-26V for this 24V battery system.

So that the treatment of the batteries can be assessed later, this controller has a built in datalogger. Every 12 hours it records the voltage measured on the connected batteries. Up to 200 data points can be stored in memory for a record of 100 days of activity. If more than 200 are collected then the earlier data points are over-written so that only the most recent 200 are stored.

24V low voltage disconnect with datalogger and display

If/when the system is returned, an LCD display can be connected which enables the 200 data points to be stepped through from most recent to oldest, and a summary is also generated which displays how many times each voltage (from 1V to 35V) was recorded over the last 100 days. Using this data it is possible to see if the batteries were left uncharged for an extended period of time (very harmful to battery life), and how often they were run down to low charge levels (also bad for batteries).

If you need a low voltage disconnect and/or a datalogger, contact neil@reuk.co.uk with details of your specific requirements.

Solar Water Heating Pump Controller with Frost Protection

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Our 2013 Solar Water Heating Pump Controller is one of our most popular products offering user programmable automatic control a the pump in a solar water heating system.

solar water heating pump controller with frost protectionToday we finished an updated version of this controller which offer frost protection. Solar water heating collectors and the associated pipework can be damaged by freezing. One way to avoid this is to pump warm water from the hot water tank around the collector(s) when the ambient temperature outside gets close to freezing. This turns the collector into a radiator, radiating heat from the warm water through the pipes and collectors which prevents them from freezing.

In general we recommend that solar water heating systems be drained in the winter to ensure that freezing and the associated damage cannot occur, but we made this particular controller for a customer in Canberra, Australia whose solar collectors have survived for 30 winters without coming to any harm. Also, although their are frosty nights in Canberra, it does not tend to get very very cold there.

The modifications to the controller make it turn on automatically at a user programmable low solar collector temperature (e.g. +5 degrees Celcius), and then turn off when the collector temperature has increased by 2 degrees. This will have the effect of keeping the solar collector from freezing, but the side-effect is that the temperature of the water in the hot water tank will go down.

If you need a controller with frost protection, please contact neil@reuk.co.uk with details of your requirements. It is however only suitable for use in areas with occasional light frosts – otherwise we still recommend draining the system for its protection in the winter.

New Product – Rainwater Toilet Flush Pump Controller

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This week we launched another new product – the REUK Rainwater Toilet Flush Pump Controller as pictured below.

REUK Rainwater Toilet Pump Flush Controller

We have been selling different rainwater toilet pump controllers now for seven years, so this new product pulls together all the experience and knowledge we have gained over all those years together with customer feedback from hundreds of users.

For simplicity, reliability, and cost, this device uses just one float switch mounted near the top of the header tank together with a mains powered pump with its own float switch protection.

Every thirty minutes the controller tests the status of the header tank float switch, and if the header tank is found to not be full then the pump is run until the header tank is full ready to gravity feed the toilet(s) in the home.

A button has been added to the controller to enable manual override of the thirty minute timer so that the pump can be force run until the header tank is full – particularly useful for system testing and topping up if required.

This device is not available yet in the REUK Shop. It is currently available for sale exclusively here for now: REUK Rainwater Toilet Pump Controller. We can also supply a suitable relay – ideally solid state, the float switch, and a 12V plug in power supply to complete full control system.

Contact neil@reuk.co.uk with details of your requirements for more information.

New Product – 12V PIR Motion Sensor Timer

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This week we have launched a new product – a timer designed for use with the 12V PIR motion sensors typically found in burglar alarm systems.

REUK Programmable PIR motion detector timer

This device is based loosely on the PIR Relay Timer we have been selling since 2007 designed to keep an output such as lighting or an alarm on for a user programmable duration after motion has been detected by a PIR sensor.

This new device does not come with a relay; instead with an up to 3 Amp 12VDC output which can be used to directly power to up to 3A of lighting etc, or which can be connected across the coil of the user’s choice of relay – solid state or standard – to switch any current or voltage as required.

The user can programme how long the output will remain on after motion was last detected in steps of 10 seconds – 10, 20, 30, 40…etc seconds as per requirements.

This device is not currently available in the REUK Shop, but is available exclusively here: REUK PIR Timer for now.

Project of the Day – Special Programmable Timer

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We had a special request for a modified version of our REUK Super Timer 2 for use setting dosing levels during plant development.

Our super timer can be programmed to close a relay for an interval from 1 second to 99 hours, and then open that relay for from 1 second to 99 hours repeating. It is a very useful and popular product, but in this particular application it was necessary to make the programming of the ON and OFF durations as simple as possible and to also display the current settings so that it was immediately obvious to anyone looking at it what those settings were.

simple relay timer with displayPictured above is our solution to this problem. The possible ON durations required were 1,2,3,4 or 5 seconds, and the OFF durations 1,2,3,4 or 5 minutes. Therefore there are two buttons – one to move through the ON options 1 to 2 to 3…etc seconds, and another button to move through the OFF options 1 to 2 to 3… etc minutes. The green LEDs show which ON option has been chosen, and the red LEDs show which OFF option has been chosen.

Because of the large number of inputs and outputs, 10 LEDs, two buttons, and a relay, we chose to use Arduino for this project, but as a standalone microcontroller as explained here: Standalone Arduino on a Breadboard so that everything could be put tidily on the one circuit board.

Project of the Day – Power Inverter Fan Thermostat

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inverter fan themostat

Today we have been working on a small thermostat controller for the fan in a 24VDC power inverter. The existing fan was too noisy and on constantly, and was replaced with a quiet and more efficient fan to keep the power inverter internals cool with the above thermostat added so that the fan is only powered when necessary.

The temperature sensor used (not pictured) is an LM335.

The user can programme this thermostat to automatically turn on the fan at their choice of temperature, and the fan will then automatically turn off when the temperature has fallen by 5 or more degrees from that level.

New Mini 12 Volt Regulator with Fuse and Switch Terminals

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mini 12v regulator with fuse and switch terminals

Pictured above is the new miniaturised version of our old (but still popular) 12 Volt Regulator with Fuse and Switch terminals designed to protect LED lighting and other sensitive electronics from damage when connected directly to a 12V battery which may give out up to 15 Volts when being charged (whether by solar, wind, or plug-in charger).

The new version is just 45mm x 45mm x 20mm in size – less than half the size of the original and also a bit cheaper too and still supplied with a couple of spare fuses. Click here for more details or to buy: Mini 12 Volt Regulator with Fuse and Switch Terminals.

New Dawn Dusk Lighting Controller – Cheaper and Smaller

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Today we started selling a new stripped-down miniaturised and more economical (almost half the price) version of our standard 12V REUK Super LDR Dawn Dusk Relay Controller. This is a five mode user-calibratable light detector triggered light/dark dawn/dusk relay controller which has  a huge range of possible applications from security lighting, poultry lighting, home automation, and much more.

Mini dawn dusk relay controller

In the new alternative version (pictured above) no relay is supplied. Instead there is a 1 Amp maximum output which can control up to 12 Watts of LED lighting or other low power device(s), or can be connected across the coil of a relay to switch any device of any voltage or current/power requirement.

The modes of operation for this controller are as follows:
Mode 1: Output on when dark
Mode 2: Output on when light
Mode 3: Output on from dusk until dawn
Mode 4: On for X hours (user programmable) after dusk
Mode 5: Off for X hours (user programmable) after dusk and then on until dawn.

This item is now available here in the REUK Shop:

REUK Mini LDR Dusk Dawn Lighting Controller for £13.95.