Thermoregulation with BTicino 3550 - Temperature and mode control from Home Assistant

[wave68runner]

Hello,

I've been looking through the documentation and discussions, but I haven't found a clear answer to my question.

From what I understand, the integration supports thermoregulation and should allow controlling the different heating zones from Home Assistant. In my setup, I can see the current temperature and the setpoint for each zone, but I don't seem to have any way to modify either the operating mode or the setpoint from Home Assistant.

Am I missing something?

Is there a specific configuration or operating mode required on the BTicino 3550 central unit before temperature control becomes available? For example, do the zones need to be put into Manual mode directly from the central unit before Home Assistant can change the target temperature?

If anyone has a working setup with a 3550, I would be very interested to know:

Which entities should be available in Home Assistant.
How to switch a zone between Auto and Manual.
How to change the target temperature of a zone.
Whether additional configuration is required.

As a suggestion, similar to the documentation that exists for the audio distribution system, it could be very useful to have a small practical guide showing:

the available thermoregulation features,
the relevant entities and services,
example dashboard cards,
and a few common automation examples.

This would make it much easier for new users to get started with heating integration.

One additional question: would it make sense to completely manage the heating schedules from Home Assistant and leave the BTicino 3550 in Manual mode permanently?

Is this a recommended approach, or is it better to keep the 3550 as the primary controller and only use Home Assistant for monitoring and occasional overrides?

I would be interested to know what architecture experienced users are using in practice and what the pros and cons are of each approach.
Thank you for your help and for the great work on this project!

[GreenGrassBlueOcean]

Hi @wave68runner,

Thanks for the detailed questions and suggestions! You are not missing anything obvious — what you are seeing comes down to a startup-hydration regression we introduced in 2.0.0b16 (plus one hardware menu setting worth verifying on the 3550).

We are working on a PR right now to fix this root behaviour and will also add the practical thermoregulation guide and dashboard recipes you suggested.

---

1. Why you see Current Temperature + Setpoint, yet cannot change Mode or Setpoint

A. Root behaviour in 2.0.0b16 (PR in progress)

In 2.0.0b16 (#675), we disabled the dimensionless per-zone status query (*#4*Z##) on physical SCS gateways because actuator-only channels could stall single-session gateways for 10 s, assuming the general broadcast (*#4*0##) would hydrate all zones instead. That exposed two startup gaps on 3550 plants (closely related to the knob_pos / Dimension 13 startup gap reported in #770):

1. Silent #0 central unit discovery: Startup discovery does not yet send *#4*#0##. Unless #0 is declared in myhome.yaml or happens to broadcast while Home Assistant is listening, Home Assistant does not know a 3550 (#0) is coordinating the bus. Subordinate zones (1..99) then fall back to standalone addressing (*#4*Z*#14*...##, *4*303*Z##) instead of central-unit #Z addressing (*#4*#Z*#14*...##, *4*303*#Z##, *4*311*#Z##), which gateways behind a 3550 reject/NACK, and zones never receive the 3550's active seasonal mode.
2. Shown setpoint while hvac_mode is still unknown: When a zone reports its ambient temperature (Dimension 0) and effective setpoint (Dimension 12, *#4*Z*12*TTTT*3##) before a mode frame (*4*...##) arrives, Home Assistant displays both temperatures, but hvac_mode stays unknown and the internal nominal setpoint slot stays unset. In Home Assistant's stock Thermostat card, an unknown mode hides/disables the temperature dial, and clicking Heat / Cool / Auto silently sends nothing because the nominal setpoint slot is still empty.

What our upcoming PR fixes:

• Probing *#4*#0## automatically at startup so the 3550 (#0), its active mode/season, its remote-control status (*4*20*#0## / *4*21*#0##), and #Z zone addressing are detected immediately.
• Hydrating cold subordinate zones (including Dimension 13 local knob offsets) and falling back cleanly to the reported Dimension 12 setpoint when switching modes from unknown.

B. One hardware setting to check on the BTicino 3550

• Zones do NOT need to be put into Manual mode on the 3550 first — sending a setpoint from Home Assistant (*#4*#Z*#14*TTTT*M##) is itself the OpenWebNet command that puts that zone into Manual override on the 3550.
• However, check that Remote Control (Telegestione / Contrôle à distance) is set to Enabled in the 3550 settings menu (*4*21*#0##). When Remote Control is disabled (*4*20*#0##), the 3550 still broadcasts temperatures and setpoints on the SCS bus (so Home Assistant sees them), but silently ignores all incoming mode and setpoint commands from any gateway.

---

2. How a working 3550 setup looks in Home Assistant

1. Entities created:
   • 1 Central Unit climate entity (WHERE = #0, central: true): controls plant-wide mode/season (auto, heat, cool, off) and exposes season, program, scenario, and holiday_days attributes.
   • 1 Zone climate entity per zone (WHERE = 1..99, addressed as #1..#99 behind #0): exposes ambient temperature, target temperature, hvac_mode, hvac_action (heating / idle / off from Dimension 19/20), and room-knob attributes (knob_pos, local_offset).
   • External / auxiliary probes (WHERE >= 100, e.g. 3455 + L4577): created as standalone sensor entities.
   • Configuration: No YAML is required once discovery probes #0 (though myhome.yaml can optionally assign friendly names — and on 2.0.0b16 right now, declaring where: "#0" under climate: is also a quick way to force #0 discovery immediately).
2. Switching between Auto and Manual & changing setpoints:
   Home Assistant's climate model uses standard HVAC mode names rather than a literal "manual" label:
   • Auto (follow the 3550 weekly schedule) → set hvac_mode to auto (climate.set_hvac_mode), which sends *4*311*#Z## and hands the zone back to the 3550's active program.
   • Manual override / change target temperature → adjust the target temperature (climate.set_temperature) or set hvac_mode to heat / cool, which sends *#4*#Z*#14*TTTT*M## and puts that zone into Manual mode on the 3550.
   • Antifreeze / Protection → set hvac_mode to off, which sends *4*303*#Z## on a zone (or *4*103*#0## / *4*203*#0## on #0 for the whole plant).
   • Dashboard cards: Use Home Assistant's thermostat card, or a tile card with the Climate HVAC modes and Target temperature features enabled (a plain entities row or bare tile card only displays temperatures as read-only text).

---

3. Architecture: 3550 Schedule Master vs Permanent Manual Mode in HA

Approach	Pros	Cons
Keep weekly schedules on the 3550 + use HA for monitoring & overrides (recommended)	• 100% SCS bus-autonomous: heating schedules, antifreeze protection, window contacts, and pump/boiler demand keep running even if Home Assistant, your LAN, or the gateway is down or restarting. • Clean override & release workflow: boost a room with climate.set_temperature (Manual) and hand it back to the 3550 timetable with climate.set_hvac_mode: auto (*4*311*#Z##), or switch #0 to off when everyone leaves.	• Editing the base weekly timetable itself stays on the 3550 keypad / Ti3550 software rather than in the Home Assistant UI.
Leave 3550 permanently in Manual + run all schedules in Home Assistant	• Everything lives in Home Assistant's UI (schedule helpers, calendars, presence, weather forecasts, dynamic energy tariffs).	• No autonomous fallback: if HA or the gateway is offline at a transition time, zones stay stuck at their last manual setpoint indefinitely. • Power cuts or season changes on the 3550 require HA startup automations to re-assert setpoints.

In practice, keeping your baseline comfort/eco weekly schedule inside the 3550 and using Home Assistant for presence-based Away (#0 → off / auto), morning bathroom boosts (climate.set_temperature → later hvac_mode: auto), and energy/weather overrides gives you the best of both worlds. We will document all of these patterns, services, and Lovelace card snippets in climate.md and lovelace_recipes.md (just like media_player.md!).

---

4. 🙏 Could you share a 2-minute Bus Monitor trace from your 3550 plant?

To be completely transparent: we are really lacking real-world WHO 4 + 3550 bus traces, and that lack of traces is directly what led to regressions like this in b16. Whenever someone shares a trace, we commit it straight into our automated CI test suite so every future pull request replays your exact gateway + 3550 bus traffic and can never silently break it again.

(Both Export Trace and Download diagnostics automatically redact IP addresses, passwords, full MAC addresses, and entity names, so they are safe to drag-and-drop directly here.)

Quick capture steps:

1. Setup: Which gateway handles WHO 4 on your plant (MyHomeServer1, F453AV, MH200… + firmware if known) and which MyHOME integration version you have installed (2.0.0b16?).
2. Diagnostics: Settings → Devices & services → MyHOME → ⋮ → Download diagnostics.
3. Bus Monitor trace:
   • Open the MyHOME Bus Monitor card, clear all filters, and click 🔴 Start Trace.
   • Click 🧹 Sweep Bus, then wait ~5 s.
   • From Developer Tools → Actions (myhome.send_message), send these 5 frames ~3 s apart (replace 1 / #1 with one of your active heating zones if Zone 1 is unused):
     1. *#4*#0## (queries the 3550 status, mode, and whether Remote Control is 21 enabled or 20 disabled)
     2. *#4*1## (full status expansion for Zone 1)
     3. *#4*1*13## (Zone 1 local room-knob offset)
     4. *#4*#1*#14*0210*1## (test setting Zone 1 to 21.0 °C manual heating via #1)
     5. *4*311*#1## (return Zone 1 back to the 3550's Auto schedule)
   • Click ⏹ Stop Trace, then 💾 Export Trace, and attach both .json files here.

As soon as we have your trace, we'll make sure the PR replays your exact plant setup end-to-end and share a test branch with you right away!

[wave68runner]

Hello,
here my answers :

1. My gateway is MH200 running with integration 2.0.0b16

2. See attachment
   config_entry-myhome-01M34WE5TYNWWJCVT8PXJ4F52P (1).json

3. I send the message like that

action: myhome.send_message
data:
  message: "*#4*#1*#14*0210*1##"

here are the result
myhome_sweep_MH200N_all_2026-11-02T12-53-15.json

For Info : My current installation is maybe not the best show model.
The plant may not be configured in the most optimal way. Originally, four zones were programmed, but I now only have two actuators connected: Zone 0 controls the boiler, and Zone 1 controls the living room.

There are still two additional temperature sensors that were previously configured for temperature regulation, but they are no longer associated with any actuators.

All temperature sensors are with the +3/-3°C adjustment knob.

[GreenGrassBlueOcean]

Thank you @wave68runner for sharing both the MH200N (FW 1.1.8 / 010108, kernel 2.3.8, distribution 3.0.1) bus trace (myhome_sweep_MH200N_all_2026-11-02T12-53-15.json) and your Home Assistant diagnostics file! Together they pinpoint why your zones display their current temperature and setpoint, why changing the setpoint or mode from Home Assistant is immediately reverted by your central unit, and one YAML setting to clean up.

---

1. Why the BTicino 3550 (#0) rejects setpoint & mode changes (*4*20*#0##)

In your trace (frames 112–117) and every 15 minutes in your diagnostics log, when the BTicino 3550 central unit (#0) answers *#4*#0##, it emits this 5-frame status burst in 113.8 ms:

Frame on the bus	OpenWebNet meaning (WHO = 4, Table 5)	Why it appears on your plant
*4*1101*#0##	Heating Weekly Program 1 active on #0	Your 3550 is running weekly heating schedule #1
*4*20*#0##	Remote Control Disabled (Telegestione OFF)	The 3550 is configured to reject remote OpenWebNet overrides
*4*30*#0##	Failure discovered in a zone	Zones 2–5 are configured on the 3550 without wired actuator outputs
*4*31*#0##	Central unit backup battery KO	The backup battery inside the 3550 central unit is depleted/missing
*4*22*#0##	At least one probe OFF	Zone 4 (Nora) periodically reports *4*303*4## (OFF) on the bus

Right at the end of your trace (frames 143–144), you tested setting Zone 1 (Salon) to 21.0 °C from Home Assistant:

1. At t = 40.371 s, Home Assistant sent [tx] *#4*#1*#14*0210*1## (set Zone #1 manual heating setpoint to 21.0 °C), and your MH200N acknowledged it (*#*1##) in 7.1 ms.
2. 113.2 ms later (t = 40.484 s), your BTicino 3550 immediately overrode the command by transmitting [rx] *4*111*#1## (forcing Zone 1 back to its automatic weekly program at 16.0 °C nominal + +1 °C local knob offset = 17.0 °C).

How to unlock remote control on the 3550:
Because your 3550 is currently broadcasting *4*20*#0## (Remote Control Disabled / Telegestione disabilitata), its firmware refuses remote OpenWebNet setpoint/mode changes (*#4*#Z*#14*...##, *4*110*#Z##, etc.) and immediately re-asserts its own schedule (*4*111*#Z##).

• On the physical BTicino 3550 front panel, open the settings/configuration menu and enable Remote Control (Telegestione / Controllo Remoto -> ON).
• Once enabled, the 3550 will broadcast *4*21*#0## (Remote Control Enabled) instead of *4*20*#0##, and it will accept manual setpoints and mode changes from Home Assistant on #0 and #1..#5.

---

2. YAML configuration note for Nora (Zone 4) and Chambre (Zone 5)

In your diagnostics (migrated_yaml_platforms.climate), your 5 zones are configured as:

• Central unit (zone: "#0"), Salon (zone: "1"), Eloisa (zone: "2"), SDB (zone: "3") -> standalone: false
• Nora (zone: "4") and Chambre (zone: "5") -> standalone: true

Even though Zones 4 and 5 only have temperature probes without wired actuator channels, your BTicino 3550 still manages all 5 zones (*4*111*#1## through *4*111*#5##). Having standalone: true on Zones 4 and 5 forces Home Assistant to address commands to 4 / 5 (standalone probe syntax) instead of #4 / #5 (3550 central-unit syntax). Removing standalone: true from Nora and Chambre in your myhome.yaml (or setting standalone: false) ensures consistent #Z addressing across all 5 zones.

---

3. What we fixed & improved in Home Assistant (#845 & #846)

Your trace and diagnostics also exposed several ways we could improve MH200N (FW 1.1.8 / 010108, kernel 2.3.8, distribution 3.0.1) + BTicino 3550 handling in the integration:

1. Trace & Regression Suite (PR #845):
   • Archived your sanitized MH200N + 3550 capture in tests/fixtures/traces/issue_466/myhome_sweep_MH200N_all_2026-11-02T12-53-15.json with a dedicated end-to-end replay test suite (tests/test_discussion_819_mh200n_3550_trace.py).
2. BTicino 3550 #0 Diagnostics, Repair Issues & Zone Setpoint Hydration (PR #846):
   • Central Unit (#0) Diagnostic Attributes & Repairs: climate.central_unit now decodes and exposes remote_control ("disabled" / "enabled"), at_least_one_probe_off (*4*22*#0##), at_least_one_probe_antifreeze (*4*23*#0##), at_least_one_probe_manual (*4*24*#0##), failure_detected (*4*30*#0##), and battery_fault (*4*31*#0##) in its state attributes (with active #0 faults recorded in gateway.device_faults in the diagnostics bundle), and automatically raises self-healing Home Assistant Repair Issues (localized in EN/FR/IT/NL) when *4*20*#0## (Remote Control Disabled) or *4*31*#0## (Central Unit Battery Fault) is reported on the bus.
   • Subordinate Zone Setpoint Hydration (Dimension 12 / Dimension 14 + *4*111*#Z##): In the Firmware Oracle, MH200N (010108, SHA 4ac640408201) forwards *#4*#0## as 24 30 34 39 39 30 30 33 30 43 30 0d ($04990030C0 across all 12 oracle gateways), whereas *#4*0## is dropped (SILENT (Drop)) on 9 of 12 oracle gateways and on MH200N (010108) emits 24 30 34 39 39 30 30 33 30 30 30 0d, ... ($0499003000 / 12 / 0E / 0D), which queries SCS address 00 (Zone 0) rather than zones 1..99 — explaining why *#4*0## gets 0 replies on your plant where Zone 0 only has boiler actuator 0#1. When Dimension 12 (*#4*1*12*0170*3## on Salon) or Dimension 14 (*#4*2*14*0150*3## on Eloisa) arrives before the zone's operating mode frame (*4*111*#Z## / *4*1*Z##), the zone now immediately hydrates both its nominal and effective target temperatures once the mode frame confirms the zone is active, and automatically marks the plant as central-unit-managed (has_central_unit = True via is_central_thermo_where, excluding #PZZ probes) whenever any central-unit #0 / #Z frame is seen.

[wave68runner]

Thanks for the feedback. I really need to Check my config because in my dreams I only program 4 of 5 zones … and I have a look and retest all the commands