Flexible and decent smart radiator TRV (UK)?

This isn't really Node-RED related, but I wanted to ask here as I know you are all on the same wavelength!

I'm looking for a couple of Smart TRVs (radiator valves), ideally:

  • zigbee or RF but something I can interface with in a more "custom" way, I have a Tasmota flashed Sonoff Zigbee hub and an RFXTrx or the Sonoff RF hub

  • Something UK-friendly, I'm not sure what the standard fitting size is? But we have bogstandard Drayton TRVs here already

  • don't mind spending a bit, ideally I'd get something from Screwfix so I can do this ASAP! There are loads of different ones on Screwfix, not sure which ones have the best DIY capabilities!

  • really don't want a separate hub, but if that's the only option to get good reliability then I will


Good discussion here - New smart wifi radiator valves from Shelly - not sure if it came to a conclusion :slight_smile:

and also here

I think that the conclusion is:

  • shelly trv work good via wifi, but they are quite expensive.
  • the eurotronics are half the price. Their zwave versio has local access (without cloud), but their wifi version currently only works via cloud. If you want local access via wifi, then you need to start intercepting their mqtt messages unfortunately. No success guaranteed...
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You forgot to say that a lot of people use Zigbee-based TRV's as most of the commercial systems like Drayton and Honeywell use these.

I can't remember what the fitting type is called but it looks like any radiator TRV from the last 30 or more years all seem to use the Drayton fittings. All the ones you get from B&Q, Screwfix, Toolshed, etc are all the same fitting as far as I can tell and all of the smart TRV's seem to come with that as standard with an alternative in the box.

I'm not either. The Drayton Wiser ones are supposed to work with Zigbee2MQTT though and are 1/2 the price of most of the other big makes. Personally I use them with the Wiser smart controller. Partly because I got the system long before I got any DIY Zigbee and partly because I wanted something that worked even if I messed up my Node-RED server. Instead, I built some tools to enable the Wiser controller to be used with Node.js and Node-RED. It still does all of its usual smarts but I can get the info I want and control things from Node-RED if I want. The main downside is that I have had to buy a Wiser Zigbee extender (a smart plug) that I really didn't want as it was more expensive than I'd normally pay and I have plenty of smartplugs already. However, at least I can control it from Node-RED via the Wiser controller anyway :grinning:

The installation of the Wiser controller was trivial by the way, if you have a standard wall plate for your existing boiler controls, the Wiser unit clips on in place of the old one - job done.

I really didn't want to mess too much with custom boiler controls - it feels to me as it would be too easy to go catastrophically wrong!

Anyway, I've been using the Wiser system for years now and I'm very happy with it. Especially since I learned how to deal with sticky valves! Occasionally have to reset a TRV and also occasionally the controller decides to wimp out (though that might well be because I'm hitting it with a couple of external API dumps each minute!) - neither of which happen more than maybe once a year (and most of the TRV's have no issues at all). Overall though, it has been pretty reliable and Drayton have continued to make small improvements. The mobile app is now much nicer than when I started and the family have no issues using it.

One of the things to watch out for is whether you want to be able to control the valve to, for example, half open, or whether open/closed is good enough. The cheap ones are usually on/off using a heated wax capsule to open or close the valve. These can take a couple of minutes to open and close. The more expensive ones use a valve motor drive which allows better and quicker control, but the interface may still only allow open/close. This type may be battery operated as they only need power when actually moving.

So - I have bought a Drayton Wiser TRV (for testing before I buy more). I have ignored @TotallyInformation 's excellent advice to purchase a Wiser smart controller for now. I already use Nest, and not sure what this meant;

Do you mean the wired version of this thing below?

Anyway, I have joined the Drayton TRV directly to my Sonoff zigbee hub, flashed with Tasmota. I can see the stat details:

I can get the temperature reported back into NodeRED, via the ADC messages that come in every 60 seconds:

The one with red circle appears to correspond to the exact temperature (this is based on mapping all those ADC values against the more official "LocalTemperature" which is sent every 10 minutes)... divided by 10 obviously.

This is all wonderful except so far I have not been able to control the set temperature. Here are the problems I have:

  1. The physical twist controller on the TRV does seem to turn the set temp up and down, but it seems only to toggle between 18.5 and 22.5. At least that's the figure reported back over Zigbee to Tasmota. I wonder if this is by design? i.e. without the wiser smart system, it defaults to a "normal" and "warm" value? There are other figures reported back that I plan to investigate. Maybe it can be controlled directly...

  2. If I send the following on Tasmota command line: zbsend {"Device":"0xBC93", "Send":{"occupied_heating_setpoint":"19"}}, Tasmota responds with Unrecognized zigbee command: occupied_heating_setpoint

I know the above is a Tasmota question, but anyone have any insight into this? I have posted on Tasmota discord and read the docs, but didn't come up trumps...

Sheesh! Story of my life!

Nothing for you to be concerned about since that is in reference to my excellent advice that you've ignored :wink: It relates to the controller which has a standard backing plate for connection to a standard wall mount used by most boiler controllers (world-wide as far as I can tell, or at least in the west anyway).

I think that 185 is the default setting that the unit comes set to from the factory. That would mean that a twist of the control would boost the temperature to 225 for 30min. If you twist again, the temp stays the same but the time increases by another 30 min.

They probably relate to the device values that you should see documented in my wiser nodes. Oh, except that you've used Tasmota so I guess things may be different.

shouldn't that be 190 anyway? The temperature values in the Wiser system are all deg C x10. That lets them avoid any floating point calculations.

I may come round to taking your excellent advice, once I fail properly :slight_smile: Which I'm sure isn't far off! I'm still unsure what these backplates you are talking about are. Do you have a pic for reference? Just want to know exactly what I will need to replace. My room thermostat location is somewhere without any existing wiring, and I'm using Nest currently (wireless).

Thanks for the comments about the TRV's interface, I didn't know that the turn is for "boost", that's far more sensible that what I expected the twist would do, which is to turn the temperature up and down.

The reason I used {"occupied_heating_setpoint":"19"}} rather than 190: the number 19 is shown in the figure sent every 10 minutes. Only these ADC and ALG values (whatever that stands for - ADC as in analog-digital converter?) seem to show the values multiplied by 10. Either way, the actual command is being rejected.

Here is one: Central heating programmer backplate | AVForums

You can also look up the Wiser controllers docs online. Try this: Drayton Wiser Instructions.pdf (directheatingsupplies.co.uk)

Here you can see the mounting plate with the controller shown about to be clipped on:

Depending on the age of the boiler and how many control channels you have will depend on which of the backplate connections are wired up but they are standardised.

If you have a more modern boiler, one of the benefits of the Wiser and similar systems is that they include OpenTherm controls which is a lot more efficient as it gives much more fine-grained control over the boiler.

I think it is because there is no display other than the LED's on the Wiser TRV's unlike the more expensive ones that have LED displays - which, to be honest, are pretty well useless.

Maybe that's a Tasmota thing. Honestly, I think I would first have tried connecting with Zigbee2MQTT as I believe you could keep the original firmware? But I'm not sure if you have that set up?

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