HeishaMon OpenTherm Thermostat Control

Overview

This project provides a complete set of HeishaMon rules for controlling a Panasonic Aquarea heat pump using an OpenTherm thermostat. The rules run directly on the HeishaMon PCB without requiring an external automation platform, though Home Assistant override capabilities are included.

Features

• OpenTherm Thermostat Control: Use any OpenTherm-compatible thermostat to control your heat pump with room temperature feedback
• Smart On/Off Logic: Intelligent compressor cycling based on chEnable signals, room temperature delta, and minimum run times
• TaSHifT Function: Automatically adjusts target water temperature and compressor frequency based on actual heat loss vs. minimum heat pump power
• Weather Compensation: Outdoor temperature-based water temperature adjustment
• Cooling Support: OpenTherm gateway cooling control with dewpoint-based safety calculations via Home Assistant
• External Override: Selectively disable control functions from Home Assistant for manual intervention
• Anti-Short-Cycle Protection: Prevents compressor damage by enforcing minimum off-times based on outdoor temperature thresholds

How It Works

The rules monitor OpenTherm thermostat signals (chEnable, room temperature, setpoint) and translate them into Panasonic heat pump commands. The system adapts water temperature targets based on the difference between heat demand and actual heat output.

Requirements

• HeishaMon PCB (large version with OpenTherm support)
• OpenTherm-compatible room thermostat
• Panasonic Aquarea heat pump
• Optional: Home Assistant for override controls and cooling dewpoint calculations