Thermostat controller but with two temperature sensors (current and source temperature)

ESPHome
1

I’m building an LVGL-based thermostat controller.
I successfully connected relays and DS18B20 sensors and was able to make basic logic.

I have a bit complicated use case:
I have a furnace that heats water in buffers (old type, non-smart).
There are two pumps, one responsible for moving water from buffers to central heating across the house and a second pump that is responsible for heating hot water.
I need to control those two pumps based on the source temperature (buffers) and target temperatures (two separate ds18b20 sensors). I’ll have two separate controllers on a single board.

Logic:
the current temperature is lower than the target temperature and the source temperature is higher than the target temperature, then turn the pump on, otherwise turn it off.

The on/off logic is easy to do without the thermostat, but I’d like to use something out-of-the-box if it’s available to have a nice UI in the Home Assistant.

2

You can use one of climate components: bang_bang or thermostat.

As per described logic You can use single-point thermostat climate controller;

Climate configuration include actual temperature sensor.
As well is possible to change climate controller target temperture(s).

On receiving temperature reading from target sensor You can change climatesettings per desired logic:

sensor:
  - platform: <xxx>
    id: target_t1
    name: 'Target T1'
    unit_of_measurement: '°C'
    device_class: 'temperature'
...
    on_value:
      - lambda: |-
          id(climate_1).make_call().
            set_target_temperature_high(x).set_target_temperature_low(x-id(hysteresis_1).state).perform();

Hope it will help.