Solar Pump Controller for Swimming Pools
Solar Pump Controller For Swimming Pools
Read about the new REUK solar pump controller for swimming pool heatingsolar | heating | electronics
We have been selling our solar water heating pump controllers now for a few years - see here for details: Solar Water Heating Pump Controller
. While this controller is suitable in most cases it is not ideal for use with swimming pools
. One key difference is the need to set a maximum temperature
to prevent the pool from becoming unpleasantly hot. Therefore, in this article we will introduce our new solar pump controller designed specifically for use with swimming pools.
Solar Pump Controller Features
Our standard solar pump controller is actually quite simple. A temperature sensor
is fitted to the hot water storage tank and another to the outlet from the solar panel
. If the temperature of the solar panel is measured to be hotter than that of the stored hot water tank consistently for 30 seconds, then the pump is switched on. The pump stays on for a minimum of 10 seconds whenever it is turned on (to protect it from being damaged by switching on and off rapidly), and then is turned off immediately if the hot water tank is measured as being hotter than the fluid leaving the solar panel to prevent the stored water being cooled.
For the swimming pool
version (pictured above) new functionality has been added - the ability for the user to programme in a maximum pool temperature. If the temperature of the pool is measured to be above the maximum desired, then the pump will not be turned on no matter what the temperature of the solar panel
. If when the pump is on, the temperature of the pool exceeds the programmed maximum for 10 seconds consistently, the pump is automatically turned off.
Connecting up the System
With our standard solar water heating pump controller
, the two sensors can be glued to the tank and solar panel outlet using heat sink compound. For measuring the temperature of the swimming pool with these non-waterproof
sensors it is necessary to make a waterproof temperature probe
. (Click here to visit our guide to Making a Waterproof Temperature Probe
- an LM335Z temperature sensor fitted inside a stainless steel tube and filled with epoxy potting compound). The finished probe can then be dropped into the pool - ideally in a shady location for accurate temperature measurement.
In order to keep the system as cheap and simple as possible, we do not include a digital display
of the measured temperatures and pump status etc. Instead, if the user would like to have the temperatures displayed we suggest the use of one or more digital multimeters
(available from as little as £4). Simply by measuring the voltage across the temperature sensors where they are connected to the circuit board, the temperature can be calculated since it equals 100 * (measured voltage - 2.73
Using the Controller
The user can programme the maximum pool temperature using the small push button on the circuit board. By pressing and holding this button down for 1/2 a second, the circuit enters programming mode - red LED on for 2 seconds. When the LED turns off, the user presses the pushbutton X
times where 1 time = maximum pool temperature of 25 degrees Cecius, 2 times = 27 degrees, 3 = 29 degrees, 4 = 31 degrees, 5 = 33 degrees and so on. After a pause of 5 seconds, the red LED flashes X
times to give visual confirmation of the programmed setting. At any time, the user can press the button for less than 1/2 a second for the LED to be flashed X
times as a reminder of the programmed setting.
Whenever the temperature of the pool is above the maximum programmed, the red LED blinks.
The controller uses a relay
to switch the pump. When the relay is energised (closing its internal switch) the green LED is lit to give visual confirmation of its status.
This controller is based around a PICAXE microcontroller
- the PICAXE-08M
. This is powered from a 5.0V regulator and has ADC (analog-digital converter) inputs which can take in the temperature sensor values and convert them into a number from 0-255. The LM335Z
temperature sensors output a voltage which is proportional to its temperature - 2.73V at 0 degrees C, plus 0.01V per degree above zero. Therefore at 25 degrees, the sensor outputs 2.73 + (25 * 0.01) = 2.98V.
The PICAXE ADC assigns a value of 0 for inputs of 0V and of 255 for inputs of 5V. For each (just under) 0.02V increase in input voltage, the value increases by 1. For example, if 2.98V (25 degrees Celcius) is input from a sensor, the ADC (using the command readadc
) converts it to 2.98 / 5.00 * 255 = 152. For the temperature comparison part of the circuit (is panel hotter than tank) the microcontroller just checks whether the voltage input from the solar panel sensor is higher than that from the tank sensor. For the absolute temperature measurement requirement (to prevent pool being heated when it is already above the desired maximum temperature), it checks if the pool is above the maximum temperature.
Buy a Solar Pump Controller
If you are interested in purchasing this or any other bespoke solar water heating pump controller
, please contact firstname.lastname@example.org
with details of your exact requirements. Prices start from around £26 to £40 including the temperature sensors.
Article Last Modified: 16:37, 1st Jun 2009
Comment on this Article
If you have any comments on this article, please email them to email@example.com
Recommended Related Articles
People who read this article also enjoyed the following articles:Make a Waterproof Temperature Probe
Find out how to make a waterproof temperature probeArticle Last Modified: 16:37, 1st Jun 2009electronics | heating | waterSolar Battery Charger With LM317T
Find out how to make a current controlled solar battery charger using an LM317TArticle Last Modified: 09:34, 30th Mar 2007solar | education | electric circuitControl Mains Powered Devices with Low Voltage
Switch mains powered devices on and off safely and simply with low voltagesArticle Last Modified: 13:07, 3rd Aug 2009general | education | electric circuit | electronicsSolar Powered Wireless Range Extender
Extend the range of your WiFi with this weatherproofed solar powered deviceArticle Last Modified: 09:49, 26th Jul 2010solar | electronics | shoppingGrid Tie Inverters
Find out more about Grid Tie Inverters - connect your RE system to the gridArticle Last Modified: 13:37, 9th Mar 2011general | wind | solar | electronicsOptocouplers
Find out more about optocouplers/optoisolators and their usesArticle Last Modified: 13:33, 14th Aug 2010electronics | electric circuit | educationConvert Digital Mains Timer To Low Voltage
Convert a cheap digital mains timer into a low voltage programmable timer relayArticle Last Modified: 10:21, 15th Nov 2008electronics | electric circuit | generalLow Voltage Battery Disconnect Circuits
Find out more about low voltage battery disconnect (LVD) circuits - used to protect batteriesArticle Last Modified: 12:47, 31st Mar 2012electric circuit | electronics | storageSolar Charge Controller
Find out more about Solar Charge ControllersArticle Last Modified: 11:12, 29th Oct 2009solar | electronics | electric circuitDo It Yourself Power Meter
Find out how to make your own power meter to measure electricity consumptionArticle Last Modified: 11:02, 7th Jan 2009electronics | education | energy efficiency