New multibus/opentherm wireless receiver

d6m

Hi!

I'm just about to buy a new combi boiler and wanted to make sure the new wireless receiver:

https://uk.installers-shop.tado.com/products/add-on-wireless-receiver-for-combi-boilers?pr_prod_strat=description&pr_rec_id=cb1ef4c72&pr_rec_pid=7718591070459&pr_ref_pid=7703808966907&pr_seq=uniform

will be able to modulate my possible replacements.

• Worcester Bosch Greenstar 8000: https://www.worcester-bosch.co.uk/products/boilers/directory/greenstar-8000-life-combi
• Viessmann 100-W/200-W: https://www.viessmann.co.uk/en/products/gas/vitodens.html#Combi-boilers
• Vaillant ecoTec

A further related question: When modulation is possible does boiler oversizing become less of an issue?

BagEPuss

Here's my perspective as a homeowner trying to get Tado to work with a Worcester Bosch Greenstar 8000.

Firstly, I watched a "Heat Geek" YouTube interview with Tado from a day or two ago and learnt that modulation (in general) is only included as a protocol within the UK wireless version, IF and ONLY IF you buy from the Tado website. This facility was removed for UK wireless products due to lack of demand, but is being re-introduced (only for devices sold from the Tado webshop).

Now let's move on to whether modulation works on a Worcester Bosch Greenstar 8000. I have a wired Tado thermostat (which always had bus modulation built-in) and have been trying to get Tado to modulate my new Greenstar 8000 boiler since I replaced my old one a month ago. At that point Tado was not compatible with the Worcester Bosch EMS+ bus used on the 8000, so I got around this by buying a Nefit Opentherm to EMS adaptor, putting the adaptor between Tado and the boiler and then setting Tado to "Opentherm".

Overall, the system "seemed" to work OK and the Tado appeared to be calling for different levels of heat. However, I couldn't prove to myself that the boiler was properly modulating, so I bought an EMS bus WiFi gateway from bbqkees-electronics.nl (just plugs into 3.5mm jack on the boiler) and started downloading data into a Home Automation monitoring set-up. Below is what I see (only applies to the Greenstar 8000):

1. I see the flow temperature setpoint changing on the boiler (from 50 - 70 degC), but the boiler ignores it! Often this setpoint is 0deg C when Tado is not calling for heat.
2. To be fair to Tado I don't know whether this is a Worcester Bosch set-up issue, as the setpoint is clearly being modulated, it's just that the flow temperature doesn't follow-it.
3. Instead, the boiler is cycling around the manual heating setpoint that is input on the boiler panel manually. I had set this to 55 deg C. When Tado is calling for heat, the boiler cycles around this quite tightly. When Tado is not calling for heat, the boiler still cycles around this temperature, but with a slow, pondering variation.
4. As a test this morning, I changed the manual heating temperature from 55 to 65 deg, and the corresponding flow temperature moved up 10 deg C, all while Tado was calling for heat. Screenshot below, with yellow band showing manual temp selection, and purple line showing temp "setpoint".
5. With my implementation the boiler modulates by cycling the burner on/off around the manual setpoint. That's not what I wanted. That's pretty much back to relay control, undertaken via the bus.

At some point I am hoping Tado will get round to updating their protocol to EMS+. I'm not holding my breath. In the meantime, I will probably re-attach the Worcester Bosch Easy Control system that was included with my boiler, to see how that works over a day or two. I would lose the control from the 10 Tado TRVs that I just bought, so that's not a permanent option, and I like the individual room control and geolocation anyhow.

Hope this helps.

BagEPuss

Here's the screenshot...

d6m

Thanks - that's helpful.

I've sent a messsage to Tado support for further information about which they can support and what setup might need to occur on their side.

Out of interest where/how are you producing the graphs?

ajp

The screenshot is from homeassistant hass.io

Rbbhghs

We have a viessmann 200 (222) with an extension box as well as the full complement of zones on a digital connection
I can confirm that the tado is setting the temp to a variety of different values depending on demand,
It still has a bias towards responsiveness so I cap the max temp on the boiler at 55deg, but other than that I think it works fine.

johnnyp78

I’ve got an ideal vogue with a Tado extension kit installed via Opentherm and it’s definitely modulating the boiler. I’ve also set a max flow temp of 55c and on low demand - when it’s approaching target temp the boiler outputs 30c temps or even lower.

Pezp

I’ve sent an email to Tado explaining that I have a Greenstar 8000 Life combi, paired with Hive and standard water radiators. My simple question is, does the new Tado thermostat function with this boiler in terms of modulation ? Thanks for and help

johnnyp78

I would check with Tado support that ebus is supported on that particular model. If it is you need either a wired thermostat or an eu model wireless receiver.

Floob

I went with the Viessmann 100-W and the Tado EU version that supports OpenTherm:

https://ie.shop.tado.com/products/wireless-smart-thermostat-starter-kit-v3-eu-version

Its all running well now and configured using Opentherm and is happily modulating.