Domestic hot water pump driver

It is a simple DHW pump driver. The assumption of this project was to create a driver, that switches on the pump depending on two temperatures: the first – in the heat exchanger and the second – temperature on the water return. This should cause switching on the pump only when the hot water is in the exchanger and currently water in the circulation is cool.

The project was based on Atmega8A and temperature sensor LM35. The one layer board has the following peripherals: two buttons, 2 temperature sensors, 2 relays, 2 LEDs and few jumpers.

Elements used in this project:

• one button
• two temperature sensors
• one relay with 5V coil, controlled by a transistor
• two LEDs to indicate the operation of the driver

5V universal power supply powers the device, because it was cheap. It needs a stabilizer, because the voltage jumps. In this project this is 7805L stabilizer. The whole was made in photo chemical method.

Program is a simple algorithm checking every 4 seconds if the temperature in the exchanger is higher than 32 degrees Celsius and if the temperature on the return is lower than 24 degrees Celsius, it switches on the pump. If water on the return is higher than 30 degrees Celsius, it switches off the pump. Additionally, there is a possibility to switch on the pump using the button. Program can also send data through external adapter RS232 <-> USB based on FT232RL to the computer.




Link to original thread (useful attachment) – Prosty sterownik pompy ciepłej wody użytkowej