Considering Tado with Worcester Bosch 30si Compact combi - advice needed!

jthackray

Hi,

I'm considering buying a Tado wireless thermostat with smart TRVs to go with my Worcester Bosch 30si Compact combi-boiler. It also has a Comfort RF controller and remote thermostat built into the front-panel. I've unscrewed the front and can see the electrical connections.

I hope you can help me with a few questions:

• it appears that in the UK, to get modulating support, it can only be done with the old extension kit ( V3P-EK01-TC-ML ) which has the 36 volt EMS bus connectors. Is this correct?
• do I need to remove the Comfort RF controller? This appears to call-for-heat in a modulating way via a ribbon-cable connector underneath the unit when the remote thermostat triggers. Would the Tado connected to the EMS bus override this? It looks like a pain to remove and I'd need a blanking plate according to the Worcester manual ( https://www.freeboilermanuals.com/assets/pdf/worcester_bosh/Greenstar-25-30Si-Compact-ErP.pdf )
• I'm still wondering whether Tado is the best solution. I've also looked at Worcester's own smart thermostat (EasyControl) and their smart TRVs, but it appears much clunkier, but does support modulation via the EMS connection. Hive doesn't modulate and appears more clunky, Nest doesn't support smart TRVs, then there's others like Eve and Netatmo. I'd prefer Apple HomeKit support, but not essential. It would appear that Tado doesn't work well if your Internet connection goes down or if Tado's AWS servers are unreachable.
• geo-fencing and room-by-room control are must-haves, given the current price increases in gas. Longer-term I'd consider a heat-pump, but far too expensive currently.

Thanks in advance! Attached is a photo with the Comfort RF controller circled and the EMS bus connection pointed to. Has anyone else done this before? How easy is it? I'm happy to use a soldering iron and do basic electronics, but I don't want to destroy my system - my wife and 5 children would not be happy if they're cold (which is why I'm considering it now in late April, and not in October).

I also read that Tado will be bringing out new hardware (thermostat?) later this year? And can you run Tado with just the smart TRVs from the app without the thermostat? That would allow me to incrementally try them out, especially with regard to noise opening/closing the valves. Hope they're mostly toddler-proof!

Thanks in advance!

jthackray

Hi James,

Yes, I bought a second-hand (old) Extension kit as mentioned above (V3P-EK01-TC-ML) from eBay for ~£70, and a black wireless thermostat starter kit from Screwfix for £99 (good price! And they give a £10 rebate) and then sold the extra new wireless receiver (without modulation) back on eBay for £40.

Then I wired it to the EMS bus terminals, and left the existing controller installed. I remember reading elsewhere (I think the ESP EMS GitHub website) that the EMS bus allows multiple devices to be connected in parallel. And yes, it just worked. The Tado installation was flawless and once I'd told it my boiler type, the EK knew it was powered by the 36volt digital bus and automatically set the wireless thermostat to D17 mode.

So, really easy install (two wires). I've then set my old wireless thermostat to 8 degrees and put it in a cupboard. If I ever move house, it's also an easy removal process (the EK is stuck onto wall with double-sided sticky pads) and I'll just swap the Tado TRVs back to the old hand-turned ones.

I did consider the Drayton Wiser system, as it also has local control via an HTTP interface, and so would connect to HomeAssistant, but Tado also allows local control via HomeKit, or remote via the app, and the Tado app is not bad really (it's been running about 1.5 months so far) and my 1970s house doesn't have thick walls, so I'm not affected by range issues. The Drayton Wiser system uses Zigbee for TRVs, so might be worth considering in a massive house, and Shelly sell WiFi TRVs, but neither of these would call for heat, which is also useful.

My wife is happy now that it will keep her warmer and pay for itself, and the children's bedrooms are too hot after 7pm whilst we can keep downstairs toasty until 11pm, and likewise, leave the heating at 16 degrees overnight upstairs on those coldest of nights, and turns downstairs radiators off. So I'm happy.

jamese8

Did you proceed with tado in any way?

jthackray

Forgot to say, you don't need to buy old kit on eBay for UK modulation anymore. Tado now announced they sell modulating wireless receivers direct as a kit - it was mentioned on the HeatGeek YouTube channel a few weeks back, and I think I've seen mention on these boards somewhere. I wanted the wireless receiver as I don't already have a wired connection - I guess I could have wired it up, but would require dragging wires under kitchen units and drilling holes in the wall through to the hallway.

jthackray

Whilst I'm here, I also found a mention of a "Tado for installers" app, or https://model-selector.tado.com/ which both allow you to see the flow temperature the boiler is operating at. The website confirmed it was modulating down, and indeed, I can hear it very quietly working for a long time, with minimal steam leaving the flue, which is great, as it's much more efficient and better for the boiler than cycling on/off every 20 mins or so. This was the main reason I wanted a modulating setup. The alternative would have been to install the Nefit opentherm to EMS gateway, then a different system (probably Drayton Wiser) but it was all built-in with Tado, as they've sensibly written the code to interface with many digital buses (e.g. EBus, OpenTherm and in my case, EMS). I prefer the all-in-one solution. Less to go wrong, hopefully.

jthackray

The Tado modulation appears to be very gentle on the boiler, starting around 57 degrees and going down to 40ish degrees for some time, then 30 degrees before it completely stops the boiler, as you can see from this screen-shot.

ColdTattie

Great info, @jthackray ! Very similar to my boiler.

td287

I bought this wireless receiver for this combi boiler and cannot figure out for the life of me the wiring. The installation app says I need to send a support request and does not provide diagrams. Any guidance much appreciated.

libjohn

I have the same boiler, but without the Bosch Comfort RF extension. I am a bit confused about what I need to get in order for the modulation to work. Do I need to purchase the Bosch Comfort RF and the old extension kit (V3P-EK01-TC-ML), or does the UK wireless version come with this now? Or is this all irrelevant, and should I just wait for the Tado X UK launch in November?