ORFHAn

ORFHAn (Open Radiant Floor & HVAC Automation) replaces the controller of a radiant floor system with standard components and open firmware. It regulates heating in winter, cooling in summer, and the dehumidifier. All the logic runs on a relay board with an ESP32: if the home network, Home Assistant, or the internet are switched off, the house continues to be regulated.

The name tells you who it is for: those who feel orphaned from their system. This happens when the display stops working, the spare part can no longer be found or costs as much as the entire controller, and a technician is required just to change a setpoint. ORFHAn is based on the right to repair: a system that is in your home should be something you can understand, repair, and connect to whatever you want. The price to pay is that, if something breaks, you are the technician.

What it does

• One temperature for the whole house, with a correction for each room (from −3 to +3 °C). The zone valves are opened and closed by a timed PID controller; those who prefer classic hysteresis can keep it.
• Four modes: off (with an anti-freeze maintenance temperature), manual, time schedule with time slots, and automatic. In automatic mode, the controller decides on its own by looking at the time and the weather, and anticipates the night because a radiant floor takes a couple of hours to change temperature.
• Automatic seasons, with heating dates taken from the legal climatic zone. It can be forced manually, with a clearly visible warning for as long as it lasts.
• A faulty probe does not shut down the room. The controller learns how much each valve works hour by hour and uses that to maintain the zone without a probe, reporting the fault on the touch panel and in Home Assistant.
• Radiax systems, pump included: the shared plant room pump is controlled via the system bus, using either the relay board or just the touch panel, and consumption readings, date and time, and the thermal season also come from the bus.
• Dehumidifier controlled based on humidity, with a minimum time between switch-on cycles to protect the compressor.
• Wall touch panel, web pages designed for the phone and integration with Home Assistant via MQTT: entities and commands appear automatically.
• Choice of sensors: commercial thermo-hygrometers, cheap sensors whose firmware is replaced with free firmware, or DIY nodes with ESP32 that add presence radar.
• Edit lock for children or tenants, manual relay testing during assembly, interface in Italian or English.

How it is made

There is only one brain: the relay board. It receives temperatures from the sensors via MQTT, decides, and commands the valves, the pump, and the dehumidifier. The touch panel, the web pages, and Home Assistant are just windows into what it decides. For this reason, a network failure or a home server failure does not stop the system.

The rooms are not written into the firmware. They are in a house file (how many rooms, what they are called, which relay each one is on), which is prepared with ORFHANizer. It is a program for Windows, macOS, and Linux that recognizes the connected device and uploads it via USB or via network using a wizard. There are ready-made templates ranging from a studio apartment to a four-room apartment with two bathrooms, up to sixteen rooms.

ORFHANizer is also available online, without installing anything: projects.eandgcode.com/orfhanizer. Using Chrome or Edge on a computer, it writes via USB, from the browser, the firmware compiled and signed every night by the release server, and immediately after sends the prepared house to the relay board on the same page. The online version cannot see the home network: to update devices already installed, there is an internet update from their menu, or ORFHANizer on your own computer.

Two ways to use it

The second method was born from a real-life case: a Radiax display that no longer responded to touch, and with it, the regulation of the entire house. The bus protocol was reconstructed by listening to it, in the twin project rehumatism. The ORFHAn panel has been acting as the display for a real system since October 10, 2026.

How much it costs

Indicative prices recorded in mid-2026, for a house with six zones:

The reference board is a Devantech ESP32LR88 with eight relays; for larger houses, there is a profile for a sixteen-relay board. The panel is an AZ-Touch with a 2.8-inch screen. An equivalent commercial multi-zone controller starts at several hundred euros for equipment alone, excluding installation.

How to install

The complete guide is in the repository. The steps are as follows:

1. On the bench, the sensors: flash the nodes and check that they send temperature and humidity.
2. On the bench, the relay board: prepare the house file, flash the firmware with ORFHANizer, and test the relays one by one, without any loads connected.
3. On the bench, the panel: flashing, touch calibration, and testing together with the relay board.
4. On site: switch off the power, replace the controller, and place the sensors in the rooms.
5. Home Assistant (optional) and calibration during the first days of operation.

Everything that can be tested on the bench is tested on the bench, before opening the electrical panel.

Status

The relay board, touch panel, and sensor nodes are tested on real hardware. On a Radiax system, the relay board controls the shared plant room pump via the bus (tested since October 8, 2026) and the panel works as a display since October 10, 2026. Many recent functions, such as the PID controller, the automatic mode, the sixteen-relay board, and internet access, compile and are tested on the PC with simulations, but not yet in a house. There is no stable version yet. Every project document openly states what has been tested and what has not.

Before you begin

• Work is performed on 230 V systems: if you do not have the expertise, a qualified electrician should handle the power connections.
• In a condominium, the pump, thermal plant, and heat meters are common parts: they may only be touched with the agreement of the building manager and the maintenance technician. Heat meters are sealed and must not be tampered with.
• By replacing the original controller, you void the warranty of the system.

ORFHAn is an independent project, released under the MIT license. Bug reports, installation reports on different systems, and suggestions for modifications are as welcome as a donation.