After a lot of reverse engineering I've published a full ESPHome integration for the Aquastrong HEX 75 pool heat pump. If you have a CHICO based unit from Aquastrong, Fairland, IPS, Poolsystems, or Aquark with a CHICO controller (My PCB was marked R-SY013-BP), this should work for you.
What it does:
- Full local control over Home Assistant — power, mode (Cool/Heat/Auto), setpoints, energy mode (Standard/Boost/Eco)
- Complete sensor visibility — water inlet/outlet temps, compressor and fan frequencies, refrigerant circuit temps, energy usage, fault detection
- No cloud required — Tuya can stay connected or be disabled entirely
- Coexists with the OEM display — both work simultaneously with no interference
- Write confirmation with retry logic — HA only reflects state the controller has actually confirmed
The interesting bit: These units have two RS-485 ports. Connecting to COM2 (the auxiliary terminal block) instead of COM4 (the display port) means completely isolated buses — the display keeps working, no bus contention, clean reads. This took a while to figure out.
The full Modbus protocol map is documented in the repo for anyone who wants to adapt it.
Happy to answer questions — and especially interested to hear from anyone with other CHICO based units who can confirm compatibility.