SONOFF TRVZB - losing valve calibration quickly when using precise control

[adriannow]

Hello, I'm testing SONOFF TRVZB thermostatic radiator valve, and I was quite happy regarding precise control of valve opening (using valve opening/closing degree) in Versatile Thermostat. Just so everyone knows, by default Sonoff only opens valve to 0/100%, so it's going through some heavy cycles.

After initial testing everything looked fine, but then I noticed that the radiator is quite warm even after few hours when the valve should be 100% closed. So I've added additional thermometer directly on top of the radiator to see how it looks in reality:

(From the top: blue line is temperature directly on top of the radiator, yellow - set temperature (it was constant 23.5 degrees). And then looking at the second graph of the "Valve open percent", even after about 3 hours the radiator was still significantly hotter than the ambient temperature (measured less than meter away). So in short, valve was definitely not closed fully.

After I reinserted batteries and reset the TRVZB, it seems to recalibrate and close fully again. After about a day the problem started again.

I'll be trying to do some automation maybe to close fully and open the valve fully from time to time, to get the thermostat to recalibrate (as this is what it does after all on default firmware). But at this point I'm not sure if this will help - just my best guess.

[jmcollin78]

Hello @adriannow ,

Can you send us the configuration of your VTherm (see: https://github.com/jmcollin78/versatile_thermostat/blob/main/documentation/en/reference.md#custom-attributes)

[adriannow]

Sure, but from the initial observation, the VTherm is trying to manipulate the valve correctly - it may just be problem with the Sonoff TRVZB itself.

Here are my settings:

hvac_modes: off, auto, heat
min_temp: 7
max_temp: 35
target_temp_step: 0.5
current_temperature: 23.2
temperature: 23.5
hvac_action: off
is_on: true
hvac_mode: heat
preset_mode: none
type: null
is_controlled_by_central_mode: false
last_central_mode: null
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
target_temperature_step: 0.5
ext_current_temperature: -0.14
ac_mode: false
saved_preset_mode: none
saved_target_temp: 23.5
saved_hvac_mode: null
last_temperature_datetime: 2025-01-16T07:54:06.573695+01:00
last_ext_temperature_datetime: 2025-01-16T07:52:43.139986+01:00
minimal_activation_delay_sec: 10
total_energy: 0.61
last_update_datetime: 2025-01-16T07:54:06.574589+01:00
timezone: Europe/Warsaw
temperature_unit: °C
is_device_active: false
device_actives: 
nb_device_actives: 0
ema_temp: 23.16
is_used_by_central_boiler: false
temperature_slope: 0
hvac_off_reason: null
max_on_percent: null
have_valve_regulation: true
last_change_time_from_vtherm: 2025-01-16T07:53:31.040855+01:00
presence_sensor_entity_id: null
presence_state: unavailable
is_presence_configured: false
power_sensor_entity_id: null
max_power_sensor_entity_id: null
overpowering_state: unavailable
is_power_configured: false
device_power: 1
power_temp: null
current_power: null
current_max_power: null
mean_cycle_power: 0
motion_sensor_entity_id: null
motion_state: unavailable
is_motion_configured: false
motion_delay_sec: 0
motion_off_delay_sec: 0
motion_preset: null
no_motion_preset: null
window_state: unavailable
window_auto_state: unavailable
window_action: window_turn_off
is_window_bypass: false
window_sensor_entity_id: null
window_delay_sec: null
window_off_delay_sec: null
is_window_configured: false
is_window_auto_configured: false
window_auto_open_threshold: null
window_auto_close_threshold: null
window_auto_max_duration: null
is_safety_configured: true
safety_state: off
safety_delay_min: 60
safety_min_on_percent: 0.5
safety_default_on_percent: 0.1
is_auto_start_stop_configured: false
is_over_climate: true
start_hvac_action_date: null
underlying_entities: climate.sonoff_valve
is_regulated: true
regulated_target_temperature: null
auto_regulation_mode: auto_regulation_valve
regulation_accumulated_error: 0
auto_fan_mode: auto_fan_high
current_auto_fan_mode: auto_fan_high
auto_activated_fan_mode: null
auto_deactivated_fan_mode: null
auto_regulation_use_device_temp: false
follow_underlying_temp_change: false
friendly_name: sonoff-versa
supported_features: 401
preset_modes: none, frost, eco, comfort, boost
underlyings_valve_regulation: 
- - number.sonoff_valve_valve_opening_degree
  - number.sonoff_valve_valve_closing_degree
  - number.sonoff_valve_local_temperature_calibration

on_percent: 0
power_percent: 0
on_time_sec: 0
off_time_sec: 300
cycle_min: 5
function: tpi
tpi_coef_int: 0.6
tpi_coef_ext: 0.01
min_opening_degrees: 
valve_open_percent: 0
auto_regulation_dpercent: 0.05
auto_regulation_period_min: 5
last_calculation_timestamp: 2025-01-16T07:53:31.012130+01:00

[adriannow]

@jmcollin78 thank you for analyzing this.

1. TRV temperature is dynamically updated by the Vtherm based on external thermometer, so TRV current temperature is displayed correctly.
2. I understand that if valve is open, then its considered heating - and it makes total sense. Its just in case of Sonoff TRVZB there's no way to know if the valve is open, if the valve_closing_degree is not updated by the Vtherm (as suggested in documentation) and constant on 100%. Only valve_opening_degree is updated by Vtherm.

So in my case for example Sonoff TRVZB is set to 23 degrees, current temperature is 22.5 (automatically aligned by Vtherm to external thermometer), valve_opening_degree is set by Vtherm to 50%, and valve_closing_degree is set to 100% (as per docs it should not be controlled by Vtherm). And... Sonoff TRVZB decides between 50-100% closing degree itself, based on its own logic, usually starting to heat when the temp drops about 1 C degree, which is quite a lot.

[adriannow]

So just to sum up - allowing VTherm to control valve_closing_degree felt like it really more precise way, and gave correct heating state - Sonoff TRVZB was forced to use selected valve open percent. I only disabled it because you mentioned:

With closing degree the hvac_action is not working as expected and Vtherm can't know if the TRV is heating or not

I would argue that it's the opposite now. For limit values like that:

And the VTherm calculated "valve opening percent":

The actual valve was opened only in instances highlighted by orange field below charts:

[jmcollin78]

Huum this is very interesting. Thank you for this.
I don't have any so I rely on report like this.

I understand if the closing degree is set, the hvac_action of the Sonoff climate was always False. Do you confirm this ?

So I understand well, we should use the closing degree but not rely on the Sonoff climate hvac_action but on the fact the valve open percent is > min. So VTherm will force the valve open percent and the hvac_action of Vtherm should be good.

Is my understand right ?

[adriannow]

No problem, happy to share details as this is quite popular valve, and ability to control it precisely with VTherm would be perfect.

I understand if the closing degree is set, the hvac_action of the Sonoff climate was always False. Do you confirm this ?

It looks like this in my case (added red boxes to highlight hvac_action=heating, because orange fields are quite hard to see:

So hvac_action of the Sonoff climate is operating as normal - if the current temperature drops about 1 C degree below set point, it just starts hvac_action (regardless of the set valve opening/closing degree).

When max valve closing degree is set to 100% (default), it looks like this:

Important thing is to note here is that 2 values that are used for control: valve_opening_degree and valve_closing_degree are actually max_valve_opening_degree and max_valve_opening_degree (default both to 100%).

So when setting: valve_opening_degree: 50% and valve_closing_degree: 50% - Sonoff was actually opening the valve to 50%. It had no other option - VTherm was always narrowing it down to 1%, and had perfect control of valve opening percentage. In this case I didn't even looked at the hvac_action, as it actually was exactly what VTherm was displaying (everything other than 0% valve open was heating).

Now when you disable VTherm managing max_valve_closing_degree (leave it constantly to 100%), then Sonoff can choose to open the valve whenever it wants (as max close value is 100%). So it usually opens it only after big temperature drop and then closes for completely again - quite similar as default Sonoff working mode.

[adriannow]

FYI I am switching back to using max_valve_closing_degree controlled by VTherm - now with 10 min heating cycle (instead of 1 originally. Hopefully this will prevent de-regulation of Sonoff valve, as this was my only initial issue (after a while not being able to close valve fully).

With 1-min cycles VTherm was adjusting valve opening percent very frequently and I think this was something Sonoff didn't predicted.