Greenstar 27 Ri with eBus wiring centre installation
Answers
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Thats the thing which worries me. It occured to me that
- The first step should be to force the timer to be fully 24/7 for CH. Then wire things in as though we are fitting a Worcester product, into the wiring centre, not the boiler- because the boiler has handed control of itself to the wiring centre.
- Second step make sure that the Tado stat is in D17 mode (whatever that is). Fit it into the BUS connection to the left of the link with the boiler.
- Third - turn up the Tado stat. If after 10 mins the zone valve and pump and boiler havent responded, we're left with only one option, ie to remove that controller.
AFAIK none of the other links need to be changed when trying thus mode, because the Tado will be talking to the boiler in HT-BUS mode which, according to @Rob is how the Tado Wired Stat should work with the system- only problem is he's not sure.
If you make this work you will be making a little history, enabling Greenstar users to use Tados in HT-BUS mode (even though Worcester call it EMS-BUS or E-BUS).
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Great thanks. I'm sure I'll make history one way or another :). I have ordered the wired thermostat which should hopefully be available tomorrow. I guess the problem is if I have to remove the controller from the boiler I will have no way to control hot water with the Tado as it's CH only. One step at a time though I guess!
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Everywhere was out of stock for the wired stat but hopefully will get one some point today. In the meantime as I was bored, I tested out the IZ3 connection. If I put the DT20 programmer on CH 24/7 and break the IZ3 bridge the boiler, pump and valve get switched off after a few mins. When I remake the bridge everything fires up again.
To be honest I'm tempted just to get the standard UK wireless stat and work it in relay mode. The reason being is I also want to add eTRVs in lots of rooms so I'm not sure how beneficial modulating the one room with the thermostat in will be anyway, unless I'm missing something fundamental?
Edit: Just noticed Bosch emailed me back to say pretty much as above I think:
Dear Simon,Thank you for your enquiry.
Tado controls are not compatible with our EMS programming. Third party programming has attempted to replicate the signal from our own controls, but nonetheless the programming languages are different and not compatible, nor supported by Worcester Bosch. We have no plans to fundamentally change the firmware of our products to make them compatible with Non-Worcester products.
The IZ3 can be used on the original model of the GS wiring centre could be used as a make/break contact as a 240Vac switch-live to trigger the heating if used in conjunction with either the DT20 (not the DT20RF currently used) or the Comfort Programmer. You would therefore need to replace the existing facia programmer with one of the two mentioned products, and fit an external third-party control to IZ3 (this can only control the heating and not the hot water) with no EMS modulation.
Best regards,Technical Support
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AFAIK the UK Wired Stat should work with HT_BUS, at least according to @Rob it should. There are two instances where Greenstar boilers have been working with Tado in non relay mode.
And yes, you have a backstop.
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IIRC dont remove the bridges when running in digital mode — because it means the wiring centre will know that it has to get out of bed and work.
First try with the existing programmer in place. If that fails pull it out and try again. If that fails, unless one of the Tado tech's gets helpful, put it all back, switch the wiring to Relay mode - but pester them anyway..
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You are using an extension kit? In relay mode it should work. You'll have to study the wiring logic in the installation guide if you want to take control of the water switch. If stuck come back.
Bosch and Worcester had a duty under European law to publish the EMS BUS spec, to provide a testing service for third parties ama to ensure that any boiler engineer had access to the specs.0 -
There's a risk of spam. I know you'll go for the relay system first because, well, its getting cold.
When you have time, look at these
Similar generations, revision of EMS-BUS. May give you an option. Definate evidence that the HT-BUS/EMS-BUS setting can work. One of these actually uses the EU extension kit!
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