CTC Controller

Retrofitting of an old CTC Ecoheat geothermal heat pump to act on electricity price fluctuations.

Interfaces

Output: Heat pump

Our heat pump does support an external control switch to be connected for activating a feature they call "Night drop". When activated, the target indoor temperature is dropped according to the setting. If Night drop is set to -5° C and activated, the target will drop from 22 to 17° C until deactivated.

Input: Electricity price

We're using Tibber and they have a great API to get the current prices.

{
  "total": 0.2328,
  "energy": 0.1658,
  "tax": 0.067,
  "startsAt": "2021-11-23T00:00:00.000+01:00"
}

Controller: USB controlled relay

I could have used a RaspberryPi (or similar) but wanted to try out the Adafruit MCP2221A Breakout, which I hooked up to my home server via USB. Using a compatible one channel relay module and some Python logic to analyze the current prices to know when we should activate the Night drop.

Installation

First, make sure to setup the required hardware and environment vars:

• TIBBER_TOKEN
• INFLUXDB_HOST
• INFLUXDB_USERNAME
• INFLUXDB_PASSWORD
• INFLUXDB_DATABASE

pip3 install -r requirements.txt
python3 main.py