In a recent firmware update for TRVZB a ‘Boost’ function was introduced that increases the Target Temperature to fixed 35 deg C for a user selected (in device properties) period of 1- 180 minutes.
TRVZB can only be set into ‘Boost’ from the device’s eWeLink cube card and from Automatic or Manual Tap to Run scenes.
When TRVZB is in ‘Boost’ the valve opening % will only be the opening % set by the user in device properties. If a valve is set to open to 10% on ‘Heating’ it will open to only 10% when ‘Heating’ for ‘Boost’
‘Boost’ cannot be initiated from the TRVZB by tapping on the Top Button.
‘Boost’ cannot be initiated from the TRVZB device CAST Card unless there is a button for a switching device (real or virtual) to initiate a scene to set the TRVZB into ‘Boost’. This also means that a TRVZB cannot be set directly to ‘Boost’ by using a Virtual Assistant such as Amazon Alexa.
There is not any indication on a TRVZB device CAST Card showing that the device is in ‘Boost’ other than the OFF Manual and A indicators not highlighted and the Target Temperature displayed as 35 deg C.
The only definitive indication that the TRVZB is in ‘Boost’ is the ‘Boost’ toggle switch indicator within the eWeLink cube card for the device and the TRVZB display showing ‘HI’ if its top knob is tapped.
We have been testing the ‘Boost’ function and feel that it is not really very useful in its current stage of development. It would be useful to understand Sonoff’s long term plans for this feature.
Currently as an alternative for TRVZB ‘Boost’ In eWeLink cube, CAST, or Virtual Assistant (Amazon Alexa) we use a set Target Temperature command to switch TRVZBs from AUTO to Manual with the stated Target Temperature and scenes that execute at 59 minutes past each hour to switch all system TRVZBs to AUTO. This gives a variable temperature boost to a maximum time of 1 hour.
Would be interesting to hear other users experiences and thoughts.
When I did the mentioned function, I gave a much larger time limit, especially when it had a heat pump.
A heat pump heats water as fast as it can take the temperature from outside (water - air). When it is -15 outside, it will take longer to heat the water in the floor and the whole house than when it is +10 outside.
According to observations, it can take more than 5 hours.
With electric boilers and solid fuel stoves, there are different conditions for heating a house. Especially when it comes to heating power.
If they gave a limit of, for example, 2 hours, it will be small for a heat pump, but it should be enough for a solid fuel stove that has a power of 25 kW and is a reasonable size house.
It always depends on the heat source, heating capacity, conditions and the areas to be heate and whether it has hot water underfloor heating, electric underfloor heating or radiators.
The 180-minute time limit of BOOST mode is essentially a balanced design that reconciles rapid heating demands, the characteristics of different heat sources, and system safety. This duration is calibrated based on the mainstream scenario: 15–24kW gas wall-mounted boilers paired with radiators or conventional underfloor heating systems.
However, heating performance varies drastically across heat pump, solid fuel furnace, and electric boiler setups. Especially in extremely low temperatures (e.g., -15°C), heat pumps experience significant heating capacity degradation, meaning 180 minutes will likely be insufficient to reach the desired room temperature—this is exactly the pain point you’ve highlighted.
To clarify a key point you cared about: there is no restriction on heating output during BOOST mode. The valve is set to 100% full open by default. The time limit is solely intended to prevent system risks such as excessive water temperature or pipeline pressure build-up caused by prolonged high-load operation of high-power heat sources (e.g., solid fuel furnaces).
For future optimizations, we will focus on two core directions:
Adding heat source type matching: The system will automatically extend BOOST duration when a heat pump is selected.
Upgrading to a dual-exit mechanism (time + temperature): BOOST mode will end automatically once the target room temperature is reached, ensuring efficient heating without energy waste.
Because we still don’t know why the boost turns itself off immediately after activation — and keeps doing it time after time. Is it by some odd design?
Thank you for bringing up this critical issue — the repeated immediate shutdown of BOOST mode right after activation is definitely not an intended design. We take this anomaly very seriously and are expediting the root cause investigation.
First, we’d like to ask you to help confirm a key troubleshooting point: is the connection between your TRVZB and the gateway stable?
If convenient, you can check the TRVZB’s signal strength display in the app; you can also try moving the gateway closer to the TRVZB and then test whether BOOST mode works properly again.
Yes, the connection is stable. All my TRVZB units (firmware 1.4.1) are connected through a Zigbee network coordinated by an NSPanel Pro (4.2.2). The network includes several router‑capable devices, and the eWeLink app reports the TRVZB signal strength as either fair or good.
All of my thermostats behave the same way when attempting to use the BOOST function, so the issue does not appear to be related to signal quality or the stability of the Zigbee connection.
This isn’t a feature that’s essential for everyday use. It can be useful, and since it already exists, it would be good if it worked correctly - at least roughly.
There’s no rush; please take your time to check what’s going on. The issue may be in the app, but since Boost is only available there, I can’t verify how it behaves in the SonoffLAN integration or in MQTT. After the latest firmware update everything became a bit chaotic, so the slider’s behavior isn’t necessarily reliable.
This means in practice that if someone has a heat pump connected to a radiator and turns it on, unless the temperature conditions outside the house are correct, it will never reach the desired temperature of 35 degrees.
Setting a time limit for a heat pump is extremely inappropriate. In main country, heat pumps run non-stop for 7 months.
In short, when you turn on boost, it means absolutely nothing to the heat pump and it will heat according to the curve. You will not reach 35 degrees in a short time and in my opinion never. And what time limit should you set when the heat pump adjusts the heating output according to the outside temperature.
Is this correct ? As when we conducted some tests with a TRVZB mounted on a ‘dry’ valve body we found the the TRVZB only opened the valve to the preset Valve Open % not 100% on ‘Boost’. For example the test TRVZB+Valve had the Valve Open % set to 10% and on Boost the valve opened to 10% not 100%. I don’t think there have been any TRVZB firmware updates since we conducted the tests. Thank you
I tried to explain that boost mode makes no sense under these conditions. But maybe they know what they are doing, I checked my statements with more experienced people than me and they said the same thing.
I suggested changes that should be designed from the heat pump to the solid fuel boiler. We’ll see if they work and try to write me the result and test method.
