Pre-sales question re v3 Wired

popshute

Hi

I want o fit a v3 Wired thermostat to our Worcester Bosch 30Ri Compact so that I can get it to modulate using the EMS BUS. In doing so I want to remove the Drayton controller.

However my wife is a complete technophobe and refuses to use an app on her phone. So…

Can we adjust the hot water from the thermostat itself? All she needs to be able to do is turn the water off and on as she occasionally needs extra hot water.

TIA

policywonk

Your boiler definitely handles EMS-BUS, the Tado interface for which is the HT-BUS, in mode D17. Many users on this community have succeeded and had a few dramas on the way, but got it working. So it can be done.

Questions:

1. Are there specific heating zone valves in place?
2. How many radiators do you have?
3. Any underfloor heating in place?

You'll need to clarify these before working out the configuration. And would strongly recommend you contact Tado Sales, asking them for the specific wiring instructions for your boiler and the V3 products needed, given the full configuration you want.

Got the fact that in EMS-BUS mode, you'll have to give up the internal controller that often comes with the boiler and that then leaves a question as to how you control HW temperature. This question must be posed to the sales team in advance, asking them to give you an unambiguous written answer as to whether the Tado interface to the EMS BUS prevents you from controlling the boiler's HW set temperature.

AFAIK the only way to set the HW tap temp is via the app. There isnt a Tado specific physical device to set HW alone. Some people claim it is possible to have a Tado CH stat become the HW temp setter, but I would strongly recommend that you get the Sales team to give you the answer in writing.

Now if they give you a merry dance, come back here, and we'll shake it up for you.

popshute

Brilliant @policywonk - many thanks

Is there an email address for Tado Sales or do I have to call them and hope that they confirm in writing? I spoke to the installer team about whether the Bosch was fully supported and they didn't inspire confidence…

policywonk

Wierd. Their sales email address has dissapeared.Their support email address is still published:

support@tado.com

If they are uninspiring, come back, let us know who precisely behaved that way.

popshute

@policywonk Got my answer. Not good news…

"I understand your question and the idea to start using BUS control of the boiler.

However, such control is not possible in the UK S and Y plan systems with a system boiler."

So that's a bust :crying:

policywonk

Something does not make sense here.
@Emcee would you get back to the support team on this?
This installation guide:
https://www.worcester-bosch.co.uk/support/literature/download/6720813282

Figures 41 and 42 provide clear descriptions on how a motorised set of valves can be controlled. In one scenario the Worcester wiring centre provides an interface between mains powered motorised valves and the EMS BUS interface. In another it handles control through its internal controller which can be fitted.
There is a third and, as i understand this, the triggering of motorised valves using local smart wired thermostats is entirely possible, when the final wireless receiver is assigned to command the e-bus and wired accordingly. It is easier if you have s plan valves.
I really don't see why support claims this isn't viable with the V3 series. @Emcee if that tech would send us the reasoning it worked be helpful.

popshute

@policywonk @Emcee I don't know if it's relevant, but I told support that I wanted to remove my Drayton LP822 controller as well and have the V3 handle the hot water (ie my question in my OP). Later in the same message support said that the V3 could not do this and recommended the wireless X with hot water support. When I asked whether this could work with the BUS on the Bosch, I was again told "no", it only works on relay (which I've already got)

Happy to post the conversation if it helps (anonymized obviously as I don't want to get anyone into trouble)

popshute

Also the Bosch website says

"The EasyControl adaptor is required for the Bosch EasyControl to work with our Greenstar regular boilers"

which should allow OpenTherm to be used with any boiler (assuming that I read it right!). Any help?

Emcee

hello @popshute and @policywonk

@popshute I can't find a support ticket linked to the email address you are using on the community. Can you let me know what name / email address you were using via private message so I can have a look?

popshute

@Emcee I'll pm you these details

popshute

@Emcee Just sent these to you via PM

Emcee

Hello again @popshute

Just had a look at your chat.

I can now see that you were speaking with Nikola, who is our most knowledgeable agent when it comes to UK (S or Y plan) systems. From that perspective alone, I would trust what he says.

Just to keep @policywonk in the loop, this was Nikola's answer:

I understand your question and the idea to start using BUS control of the boiler.

However, such control is not possible in the UK S and Y plan systems with a system boiler.

Your Greenstar 30Ri Compact is a system boiler which is activated by the Zone Valve(s), and only with relay controls. For the heating system to operate correctly only that type of control is possible, and only with On/Off relay controls.

Your Drayton programmer controls the Zone Valve(s), and not the boiler directly.

It is not possible to connect tado° to control a system boiler directly.

@popshute, just to re-iterate / clarify points made by Nikola:

• with tado° X, only Relay (on/off) and OpenTherm protocols can be used. So if you were to purchase tado° X, Bus control would be out of the question altogether.
  
• with V3+, Bus is possible for some homes, but not yours. This is because of your system boiler, which relies on on/off zone valves (Relay control). If you were to install V3+, you would lose modulation.
  
• With tado° X, specifically tado° Wireless Smart Thermostat X - Starter Kit incl. Programmer with Hot Water Control and OpenTherm recommended by Nikola, you could benefit from modulation via OpenTherm. "Programmer with Hot Water Control" would replace your current Drayton programmer.

I'll let Nikola know about this thread. @policywonk maybe he will have a closer look at the information you've provided.

popshute

@Emcee Thanks for looking into this. As I said above it's a bust 😉

Although I could probably use OpenTherm with my setup, according to Bosch I need to buy their EasyControl Adapter, which introduces another level of complexity with associated possibility for failure.

It's too much of a risk for me that I might end up back where I started. I've already got a relay smart thermostat so I'll stay with that and ignore modulation.

Thanks again for your help (and @policywonk ) - very much appreciated.

wateroakley

@popshute Looking at your boiler manual, the technical data on page 9 says the 30Ri can reduce (modulate) the heat input from 30kW to a minimum of 7.15kW. That will help with boiler efficiency in relay mode.

policywonk

@popshute . Hi again. Having consulted around, there does seem to be a simple route to get you to where you need to be in EMS-BUS mode if needed. However this needs to be discussed with Worcester Bosch.

In Figures 41 and 42 of the installation guide: Worcester Bosch boiler guide describe the capacity to include their wiring centre which connects to the boiler in EMS-BUS mode and which allows zone valves to be wired into that add-on. From the manual it seems that one can then wire in:

• EMS-BUS thermostats for the Central Heating side
• EMS-BUS sensor (made by Worcester Bosch) for the Hot Water Cylinder.

If you are still interested in exploring this, it would mean that a V3 series setup is required but you would need to have clarity from Worceser Bosch technical support on whether your boiler can operate with that wiring centre, in EMS-BUS control mode, using WB's temperature sensor and, also allow you to operate an external EMS-BUS control for the central heating, giving their wiring centre the job of switching the motorised valves. It may need one of their approved engineers to fit that wiring centre.

Do let us know if you do proceed and what you hear back from Worcester Bosch. You arent the only person to face this hurdle. There were others, who did report having sorting this with EMS-BUS in control directly, but I havent had a response from them yet. If they do, they will pitch in here.

popshute

@policywonk

I've spoken with Bosch tech support and they say that this cannot be done. They tell me that I have 2 Honeywell valves controlling heating and hot water. These valves are powered by 240v as is the Honeywell thermostat, but their BUS requires low voltage.

Apparently they don't have any 240v products that can be made to talk to the BUS and the valves.

Thanks for trying to help. I really appreciate it.

policywonk

Would you be open to contacting them again? They do various wiring centres, such as those illustrated in Figure 41 and 42 in the installation guide for your boiler. This link refers to one:

https://www.plumbnation.co.uk/documents/greenstar-wiring-centre-installation-and-servicing-instructions-2.pdf?srsltid=AfmBOoqm3TtjBHVXh7Vd3iLShtJYrY4yDSJU1iXqbnJ-0FplkWWayssH

From that guide it seems to enable hot water tanks to be managed and zone valves to be managed.
I know that this is genuinely troubling and so if you decide to call it a day, will understand. Heres a scenario to give to WB or to a local WB service engineer who really knows their products. What if:
* fits their wiring centre to define where heat goes and how, but connected to the EMS-BUS pair.
* either wires in the zone valves into that wiring centre, or only wires in the zone valve for the HW cylinder and replaces the zone valve for the CH side with an automatic bypass valve;
* the aim is to remove any obstacles to a remote EMS-BUS compatible programmer and thermostat to be wired into that wiring centre and onto the EMS BUS - as long as it is NOT EMS-BUS 2.

Is there still an obstacle? What would it be? Figures 41 and 42 are clear that this can be done.

Edit: have just edited the concept so that it can be conveyed more clearly to a Worcester Bosch tech.