Set up for Hysteresis on Sonoff TRVZB

[jamesonuk]

I have a bunch of Sonoff TRVZB devices which I have setup with VT as over climate devices with direct control of valve regulation.

This is largely working fine but the TRVs are set with a hysteresis setting of -0.5C (has to be between -0.2 and -1 https://www.zigbee2mqtt.io/devices/TRVZB.html#temperature-accuracy-numeric)

which means that I am seeing the VTerm as heating (and therefore firing up the boiler) but the actual valve as idle
so real TRV shows as

whilst VTherm is

but the actual radiator is just sat there and ambient temperature means it isn't actually dropping low enough to kick back in and isn't warm. The boiler however has been on for an hour and a half making rooms without TRVs very hot when this the only TRV actually saying it needed heat.

What should the setup be to account for this?

hvac_modes:
  - heat
  - sleep
  - "off"
min_temp: 7
max_temp: 35
target_temp_step: 0.5
preset_modes:
  - none
  - frost
  - eco
  - comfort
  - boost
current_temperature: 18.9
temperature: 19
hvac_action: heating
preset_mode: none
hvac_mode: heat
ema_temp: 18.84
is_ready: true
specific_states:
  is_initialized: true
  is_on: true
  last_central_mode: Auto
  last_update_datetime: "2026-05-18T20:55:07.047249+01:00"
  ext_current_temperature: 10.45
  last_temperature_datetime: "2026-05-18T20:51:01.713386+01:00"
  last_ext_temperature_datetime: "2026-05-18T20:53:27.030994+01:00"
  should_device_be_active: true
  is_device_active: false
  device_actives:
    - number.playroom_trv_valve_opening_degree
  nb_device_actives: 1
  ema_temp: 18.84
  temperature_slope: 0.02
  hvac_off_reason: null
  total_energy: 13.47
  last_change_time_from_vtherm: "2026-05-18T20:53:32.424450+01:00"
  is_sleeping: false
  is_locked: false
  is_recalculate_scheduled: true
  not_initialized_entities: []
  messages: []
  auto_tpi_state: "off"
  auto_tpi_continuous_kext: "off"
  auto_tpi_learning: {}
configuration:
  ac_mode: false
  type: over_climate_valve
  proportional_function: tpi
  is_controlled_by_central_mode: true
  target_temperature_step: 0.5
  timezone: Europe/London
  temperature_unit: °C
  is_used_by_central_boiler: true
  max_on_percent: null
  have_valve_regulation: true
  cycle_min: 5
  minimal_activation_delay_sec: 10
  minimal_deactivation_delay_sec: 0
preset_temperatures:
  frost_temp: 7
  eco_temp: 7
  boost_temp: 7
  comfort_temp: 7
  frost_away_temp: 0
  eco_away_temp: 0
  boost_away_temp: 0
  comfort_away_temp: 0
current_state:
  hvac_mode: heat
  target_temperature: 19
  preset: none
requested_state:
  hvac_mode: heat
  target_temperature: 19
  preset: none
is_presence_configured: false
is_power_configured: false
power_manager:
  device_power: 1
  mean_cycle_power: 0.15
is_motion_configured: false
is_window_configured: false
is_window_auto_configured: false
is_safety_configured: true
safety_manager:
  safety_state: "off"
  safety_delay_min: 60
  safety_min_on_percent: 0.5
  safety_default_on_percent: 0.1
is_lock_configured: true
lock_manager:
  is_locked: false
  lock_users: true
  lock_automations: true
  lock_code: false
  auto_relock_sec: 30
timed_preset_manager:
  is_active: false
  preset: null
  original_preset: null
  end_time: null
  remaining_time_min: 0
is_heating_failure_detection_configured: true
heating_failure_detection_manager:
  heating_failure_state: "off"
  cooling_failure_state: "off"
  heating_failure_threshold: 0.9
  cooling_failure_threshold: 0
  detection_delay_min: 15
  temperature_change_tolerance: 0.5
  failure_detection_enable_template: null
  is_detection_enabled_by_template: true
  heating_tracking:
    is_tracking: false
    initial_temperature: null
    current_temperature: null
    remaining_time_min: null
    elapsed_time_min: null
  cooling_tracking:
    is_tracking: false
    initial_temperature: null
    current_temperature: null
    remaining_time_min: null
    elapsed_time_min: null
  root_cause: null
  root_cause_entity_id: null
is_repair_incorrect_state_configured: false
is_auto_start_stop_configured: false
fan_mode: null
fan_modes: []
is_over_climate: true
regulation_accumulated_error: 0
regulated_target_temperature: null
vtherm_over_climate:
  start_hvac_action_date: "2026-05-18T20:55:07.047199+01:00"
  last_mean_power_cycle: 0.15
  underlying_entities:
    - climate.playroom_trv
  is_regulated: true
  auto_fan_mode: auto_fan_high
  current_auto_fan_mode: auto_fan_none
  auto_activated_fan_mode: null
  auto_deactivated_fan_mode: null
  follow_underlying_temp_change: true
  auto_regulation_use_device_temp: false
  regulation:
    regulated_target_temperature: null
    auto_regulation_mode: auto_regulation_valve
    regulation_accumulated_error: 0
  temp_synchronisation:
    sync_entity_ids:
      - number.playroom_trv_external_temperature_input
    sync_with_calibration: false
    sync_attributes:
      number.playroom_trv_external_temperature_input:
        value: 18.9
        min_sync_entity: 0
        max_sync_entity: 99.9
        step_sync_entity: 0.1
valve_open_percent: 15
power_percent: 15
on_percent: 0.15
vtherm_over_climate_valve:
  have_valve_regulation: true
  valve_regulation:
    underlyings_valve_regulation:
      - - number.playroom_trv_valve_opening_degree
        - number.playroom_trv_valve_closing_degree
    on_percent: 0.15
    power_percent: 15
    function: tpi
    tpi_coef_int: 0.6
    tpi_coef_ext: 0.01
    tpi_threshold_low: 0
    tpi_threshold_high: 0
    minimal_activation_delay: 10
    minimal_deactivation_delay: 0
    min_opening_degrees: ""
    opening_threshold_degree: 0.5
    max_closing_degree: 100
    max_opening_degrees: ""
    valve_open_percent: 15
    auto_regulation_dpercent: 0.5
    auto_regulation_period_min: 5
    last_calculation_timestamp: "2026-05-18T20:51:01.714378+01:00"
  underlying_valves:
    number.playroom_trv_valve_opening_degree:
      hvac_action: heating
      percent_open: 15
      last_sent_opening_value: 15
      min_opening_degree: 0
      max_opening_degree: 100
friendly_name: Playroom VT
supported_features: 401

[jmcollin78]

Hello,

Your case seems to be a matter of valve tuning as explained here: https://www.versatile-thermostat.org/en/docs/self-regulation/#how-to-properly-adjust-the-parameters-that-control-the-opening

Your valve is open at 15%:

percent_open: 15
last_sent_opening_value: 15

but the minimum opening to heat is set to a very low value:

opening_threshold_degree: 0.5

and so it is heating.

First you have to fix some values:

• auto_regulation_dpercent should be set to 5 (and not 0.5). I know this is confusing in the configuration UI but for valve is it in percent and should not be under 3 to avoid calibration lost issue,
• opening_threshold_degree should be set to 5 also (and not 0.5) or more.

Second you have to find the right values for your installation as explained in the link above:

• opening_threshold_degree: you have to find the good value: at which percent the water starts to flow into your heater. May be it is 15 in your case (if your TRV don't heat and your valve is open at 15%),
• min_opening_degrees: set it to opening_threshold_degree at first try. Maybe it is 15 in your case to

[jamesonuk]

Thanks, will go through this properly when I can. I haven't looked at the code but perhaps it would be prudent to default auto_regulation_dpercent and opening_threshold_degree to 5 not 0.5 when using valve control over climate?

[jmcollin78]

I will have to change this. This is too much misleading.