I believe this is more due to the temperature sensor is only reporting in 0.5 degree increments.
I think that if you pair that with a better sensor then the temperature will be better.
But I agree that a product shouldn’t vary that much.
Thanks for your review. It feels like there is still no “good” solution for controlling a radiator valve?
I’m looking in the direction for a “dumb” valve controller, controller via an ESP-board. But I have underfloor heating with all my valves centralized (per floor).
If you need to set the valve position then this will be compatible with ESP-Home
EMO T
If you can live with on/off then there are cheaper versions of these
Thanks for the suggestion.
I have read the technical specification of this valve. I am not sure this actuator can remain at a partially open state (e.g. 20% of the water is allowed in). I think PWM control means that 20% implies that the valve will be open 20% of the time and then will be closed 80% of the time. Depending on the duration of the duty cycle, the valve is opening/closing quite a lot during the day.
If this is what PWM actually means, I am not sure what the advantage of this actuator is compared to the simple on/off actuator.
But I have the feeling I am missing something…
What part makes you think that?
This type of actuator work by heating it internally and this heat makes the actuator move.
There is a study which I have posted here from some university (I think it was) that experimented with PWM on normal on/off actuators. I think I remember it as they measured the movement it did when giving them PWM.
And even if it is then it will just work as most electric thermostats work with a bimetallic strip.
It seems everyone is so afraid of on/off but this is how thermostats always have worked.
The only this you need is make sure the on/off happens frequently enough, meaning the temperature range of the thermostat should be low, which it can be with digital temperature sensors.
Here is the study
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I’m not sure myself, but in the Emo T documentation I read “the high performing
EMO T actuator offers reliable on/off control”. So I assumed that if you send “20%”, it will just be open (“on”) 20% of the time. Something like this:
But again, I’m still learning. So you are saying that if this PWM controlled actuator is heated, it is just opening a specified percentage?
I couldn’t find the link the that study you mentioned (at least not in this thread), but I would like to read it. Can you re-share?
The reason why I am (conceptually) reluctant to use on/off actuators is that I have a quite “motionless” temperature control at this moment. All my valves are open a specific percentage and it is already balanced quite well (without the use of any TRV/actuator). I would like to avoid that I install a lot of actuators that are opening/closing all the timing and thus consuming energy and wearing out and/or breaking for only marginally better results.
What kind of device do you have that does this?
Something like this?
If yes then you should read up on how they actually work.
I saw that too but in one of the documents on the page it says:
Stroke:
4,7 mm; valve position visible due to
position indicator.
The actuator does not consume more energy because it open/closes. It consumes energy when it is open, and nothing when it’s powered off.
Most of them consumes about 2w. I believe that will be less than you spend on batteries for battery operated TRVs.
Thanks a lot for sharing this information.
For other, in summary:
- Electrothermal actuators have slow response times, making them unsuitable for achieving intermediate valve positions using PWM.
- Tests conducted on actuators from multiple manufacturers showed that the actuators behaved in a step-like manner with PWM, rather than offering smooth control.
- While PWM effectively modulates average voltage for LEDs and DC motors, it fails to do so for electrothermal actuators, which require longer activation times.
The study concludes that PWM control for electrothermal actuators is better understood as a modified two-point control rather than true continuous modulation.
I have something like this:
I’m not sure, but I don’t think it controls the water capacity based on the temperature (unless you add thermoelectric actuators we are discussing). So for now, some of these zones are fully open/fully closed or partially open and stay that way until I do a manual intervention.
But anyway, I’m slowly getting convinced the added value of PWM controlled actuator is too little (or virtually zero) to offset the extra cost (and potentially additional complexity).
Ok… you are correct then.
I believe so too.
If you know that some pipes are always restricted to x amount then there are restrict plugs you can add to the pipes (not sure if it works with underfloor heating pipes, but they exist for other pipes and it’s the same dimension as far as I know).
In theory, that should be the same as setting a valve that you have to 50% and leaving it there, but with the added actuator that you can switch it off.
But this is pure speculation.
I bought a DANFOSS ALLY on amazon.de for 51€. It’s now €59, though (exact offer I bought, seems price changed): https://www.amazon.de/dp/B08DRCVDG4?ref=ppx_yo2ov_dt_b_fed_asin_title
Ah, researching my shopping history reveal I made a mistake looking up price I paid for the SONOFF: I paid just €33 for it, but I ordered together with a temp sensor and paid €51 for the package. Probably misinterpreted that earlier. Sorry.
So yeah, the SONOFF is way cheaper, but 90 quid for the Danfoss seems overpriced. That’s 106€ and you can get it to germany for €60 from multiple suppliers: Danfoss Ally Heizkörperthermostat (014G2460) ab € 58,39 (2025) | Preisvergleich Geizhals Deutschland
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I wonder if this is one of those unfortunate post-Brexit import tax issues (or is it price gouging) which we now have to put up with in the UK. Thank you for the response, I may see if I can order from a German site and save my self a whole lot of expense!
Although now I am checking and finding the Danfoss Ally for £63 (here) which is much cheaper than I found before
I have set my home up using Sonoff TRVZBs using a Sonoff SNZBP-02P temperature module to control them through Home Assistant and a bit of NodeRed to adjust them based upon the temperature of my smart Thermostat