ArduHeatPumpControl

ArduHeatPumpControl V1.0
Arduino based heat pump control unit with touch screen by Zeppelin500

Developed for a water-water heat pump but also usable for a brine-water heat pump. Main components are an Arduino Mega, a Nextion display NX3224K024_11 and onewire DS18B20 sensors.

I´ve devoloped it for my defect Dimplex WI9TE control unit (Wärmepumpenmanager) but it should work in the most HPs with a thermostatic expansion valve.

Programmed are (only) the basic usecases that I use:

outside temperature controlled (heating curve)
summer / winter mode
direct underfloor heating without a mixing valve
(drink) water heating
water heating is prefered before heating
electric provider blocking (EVU-Sperre)

Highlights:

touch display with differend pages to control and manipulate
some safety precautions (high/low pressure, icing, flow, proof of plausibility of all temperatures, watchdog)
Error memory with timestamp and state of all readings in EEPROM
RTC
heating curve offset and both hyseresis can be manipulated with touchscreen (heating curve is hardcoded)
6 independend onewire buses implemented, so you can replace a sensor without touching the software

The Project includes 2 files. The Arduino .ino file and the .hmi file for the Nextion display. Although the display is high potent the "intelligence" is only written to the Arduino code. The display is only used to show values and notice touch buttons. Also the build in rtc with the battery is used for the Arduino time.

Thanks to Seithan for the great Nextion libary "EasyNextionLibrary"! The Libary was the key to deal with the touch "easyly".

Caution:

If you try to implement the control unit to your heat pump, you should be educated as electrician, because you have to deal with 400V! This code is in real operation since about 10 month and it works perfect. Warning: If you don´t know what you are doing, your compressor may get damaged.

Note:

GUI and most comments are in german language, because I wrote it for myself.

Known issues:

First I used for the pressure failurs hardware interrupts. But I had some EMC problems, so I commented it out and programmed the failure detecting (laborius) manually around the switching moment of the contactor (causer of the emc problems). The EMC problems are now fixed but the code works reliable. At the moment I´m not sure if I should delete or reimplement the interrupts.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.