Wired thermostat installation - no COM port

Adam2102

Hello,

I am trying to wire in a wired thermostat directly to my Greenstar 8000. I realise that this won’t allow for modulation, however, I am seeking individual room control which my current system will not allow.

How do I wire in my Tado wired thermostat directly to the boiler? There are no COM ports…

Rob

My documentation is sceptical about this boiler, but I am not sure. My documentation discusses the Switch Live CH demand connector on page 42. Which won't work with a stat. I think something else might work though. I am seeing this on page 43 of the manual you linked to. The bottom of my screenshot is what I mean. On/off thermostat input.

It can only work if our stat is configured to relay too though. Now if this does not do the trick, I'd contact support.

Adam2102

I should have said - wiring diagrams available on pages 41-43 of the manual - https://www.worcester-bosch.co.uk/support/literature/download/6720883865

KevinBird

I also have this question, as just about to have the 8000 plus boiler installed.

I was wondering if you can still use the Low voltage Analog/Digital to the EMS Connections, even though it may just work like a relay?

if not then could take the 230v output (L) to Tado "COM" terminal, then the Tado "NO" into the Switch Live Return on the Boiler (CH terminal) ?

Adam2102

I ended up using the low voltage Thermostat on/off input terminals and use it as a relay. Works perfectly! My advice is to take the boiler off eco mode as Tado effectively does a basic form of modulation even in relay mode (ie taking into account warm up times etc).

KevinBird

Thanks Adam,

So to confirm.
You have the Analog/Digital terminals in the Tado Thermostat wired into the On/Off Thermostat terminal in the boiler right?
or did you wire the "Com"/"NO" Terminals in Tado to the On/Off terminals in the boiler ?

I read that the 8000+ boiler I'm having installed does it's own internal modulation of sorts, but monitoring the Temp out against the flow return temperature.

Mines also coming with the Bosch Easy Control, but I think I will leave that not connected for now, and use Tado

edit: Thinking about it you must have used the Analog/Digital connections on Tad, since the boiler end is low voltage right?

Adam2102

From memory it was NO and COM as this is what I had used with a previously installed wired thermostat in another property.

KevinBird

Thanks for the Info @Adam2102

My Tado was connected to my old boiler (Worcester Bosch 42-CDI) via EMS using Control D17 (HT-BUS) which worked.

I have just had my Worcester Bosch 8000+ installed. Which from what I've read supports EMS2.
I also read that Tado do not support EMS2.
However…
I connected the Tado Wired Thermostat to the boilers EMS (1) and (2) connections using the original settings on the Tado, and it would not fire the boiler in a call for Heat.
I've switched the Tado to D27 (Bosch EMS+) and the call for heat works now.

So the questions are now.
1) When using this EMS type connection is it going to modulate my boiler?
2) If is doesn't modulate will this override the internal modulation of the boiler (which apparently reads the differential between outgoing and incoming flows)?
3) Should I rewire this and use the "On/Off Thermostat" connections and COM/NO, and use Relay mode (R01) ?

KevinBird

I was about to upgrade to Tado X, but without support for ems2 in v3+ or X, Tado is no longer useful as it shoud be.

I've given up on Tado now.

Emcee

@KevinBird

Are you sure V3+ doesn't work for ems2? Where did you find this information?

KevinBird

@Emcee It does/can work with older Worcester Bosch Boilers with HT-EMS. Possibly some others Bosch ones with EMS+ ?
It will also work on Relay (R01), On/Off Mode, but this will NOT modulate the boiler.
All new boiler installations in the uk have to confirm to EnergyPlus Regulations. This means having some of Weather Compensation,Load Compensation, or smart controlling. Tado conforms as the latter one only. so no real Modulation control on the boilers.
EU however legislate that boilers have OpenTherm, which is a way better approach.

This thread is talking about "new" Worcester Bosch boilers (2000,4000,8000,8000+) which have EMS2. Tado doesn't support this, even though EMS2 has been around and used for over 2 years.

So for me, it's more important to have a control system that can modulate the boiler to gain the energy efficiencies. This means I now have to Dump Tado after so many years.
So I'm switching to EasyControl and ETRV's. It's going to take a while to recoup that outlay cost, but having a properly functioning modulating heating system will help expedite that.

It's genuinely sad for me, as I loved the Tado platform, which met so many of my requirements.

In fact I looking to update to Tado X, but this lack of EMS2 support is a deal breaker.

Emcee

Hello @KevinBird

Thank you for the explanation.
You are correct, tado° V3+ does not support EMS2 (I also confirmed with my colleagues).
I can understand why this is a deal breaker.
You might want to create a feature request. Could make a difference…

KevinBird

@Emcee I doubt it since this feature requests have been made for over 2 years and it’s still not supported.
Very very sad!