API & Opentherm

LizeNW14

Hi

I'm about to get a new boiler (Atag IC economiser) which has opentherm capability.

I'm v interested in the Tado v3+ controller, as it's the only one which allows for a 14 year boiler warranty AND has an accessible API.

I'm aware that the UK controller doesn't have Opentherm - I'd need to buy either an extension kit or an EU version.

Apparently the lack of opentherm isn't an issue, as the boiler has external weather compensation which controls the heating variance accordingly - I'm still looking into this.

If I stick with the UK version, are there any limitations regarding what data is accessible via the API?

Also, if I choose to get the extension, is there a particular version I need to get? I've heard ( so anecdotal) that the latest version doesn't have OT support.

Cheers

johnnyp78

You’re right, the uk starter kits no longer have Opentherm 🙄. Opentherm wise, you need to get Tado’s discontinued extension kit, which starts with serial no BU. Or as you said, buy the EU version of the starter kit. Can also use the wired thermostat connected directly to the boiler as an Opentherm controller, though Tado seem to discourage this.

johnnyp78

Just to add there might be a conflict issue with using Tado in Opentherm mode and the boiler having weather compensation, though Tado support or your boiler manufacturer should be able to tell you.

LizeNW14

Thanks for such a quick response.

Shame the OT extension has been discontinued - I'll have to check with Atag to see if the 14 year warranty can be obtained with the EU version - their documentation doesn't strictly say that it only applies to the UK version.

Unfortunately some of ATAG's blurb only refers to Tado wireless, not wired, but I'll query it with them.

Good shout re. OT/weather comp conflict - probably why the boilers come with weather comp, but will check.

Regarding readings from API, are there any downsides to having a non-opentherm controller, or is it exactly the same as one which does have OT?

Cheers

johnnyp78

I’m afraid that’s not my area of expertise but I suspect with 230v connections you’d get far less info from the boiler - i.e no flow temp or return temp and no modulation settings. Maybe someone with more knowledge can add to this.

GrilledCheese2

@LizeNW14 the wired thermostat is OpenTherm certified. You only need the wireless receiver (extension kit) if you don't have wiring in the room where you want the thermostat.

Rob

Can also use the wired thermostat connected directly to the boiler as an Opentherm controller, though Tado seem to discourage this.

We don't really discourage this, but it needs a context. It depends on the home really. The UK has very different heating setups/wiring than other European countries. Like using a relay for domestic hot water or the wiring centres, that's all rather UK-specific. In my native the Netherlands, for example, it's common to have a wired (digital) thermostat in the living room that is controlling the boiler directly, without any valves and programmers and whatnot in between. The main differences between the markets and the feedback we've received caused us to have a specific UK-only wireless receiver (serial number BP...) with 2 relays and no bus (like Opentherm) connection, where the EU version (serial number BR....) has 1 relay and does support bus connections. These devices are, based on the feedback we've received, much easier to install and setup than the previous generation (serial BU....) which had 2 relays and bus and was available in the EU + UK.

Anyway, the wired thermostat in the UK does support a bus connection. And we recommend using this connection when applicable. Otherwise we would have cost-cut it out of the thermostat a long time ago.

The main question is about the available wiring in the home. Is it relatively plug and play to wire the thermostat to the boiler? We discourage non-professionals from making big changes to the wiring inside the home, and encourage non-professionals to just use the wiring that's available and simply replace old devices with ours.

johnnyp78

My personal feeling is that given our rocketing energy prices here in the UK, there's going to be a lot more interest from people in trying to find ways that can save them money, such as modulating their boilers with opentherm. Maybe Tado would want to consider reinstating it in future? It seems like the obvious way to do it, if you've got a compatible combi boiler, rather than these horrendously complicated system boiler set ups anyway.

I found the BU extension kit very easy to install but maybe that's just me. The others also seem very simple. If I had known about the lack of opentherm, I probably would have gone for the wired starter kit, wired in the thermostat next to the boiler then used the TRVs as temp sensors, rather than sourcing a second hand BU kit, but both ways seem to work fine.

brewmook

I've got a ~2017 Atag iC Economiser 27 and have just been told by Tado support that it's not suitable, despite having an OpenTherm bus connector.

The support person asked if I had a One BCU module, which I don't. Why do I need that if the boiler natively supports OpenTherm and so does the wired Tado thermostat?

brewmook

Oh, and @johnnyp78, did you get it working with your Economiser? Is it a more recent Economiser +?

Hunter

even if you don't have wiring in the room that you require the thermostat, get an additional wireless temp sensor. So much is made of the lack of OT on wireless, I don't get it given the wired is available with the temp sensor.

I have S plan so.............

johnnyp78

@brewmook I’m afraid I have an ideal vogue boiler. Absolutely no problem with Opentherm and Tado on that if you’re considering switching in future.

I don’t know why I said Tado seem to discourage using a wired thermostat for Opentherm btw. Maybe I was drunk when I wrote that.