Tado with Worcester Greenstar 37CDi

Northgate

I currently control my Worcester Greenstar 37CDi combi boiler in the lobby with a Nest learning thermostat in the lounge (Nest heat link in the lobby).

I have a total of 14 radiators in my house, 12 with TRVs and 2 without.

I would like to replace all the valves for Tado Smart TRVs and do away with the Nest.

Can I fit Tado smart TRVs to all radiators, or must one remain non-TRV?

I really want to use OpenTherm as I understand my boiler supports this.

Which products will I need to purchase? Can somebody give me a shopping list?

johnnyp78

If you want opentherm you need the eu wireless starter kit, or the wired starter kit, plus as many Tado trvs as you want to fit. Bear in mind they will all need to be in range of the bridge. Usually a good idea to leave one lesser used radiator trv free in case you don’t have a bypass valve.

I would double check that your boiler supports either Opentherm or its own ebus with tado support.

Northgate

Thank you for your quick reply.

Can I position the bridge centrally in my house or must it go next to the boiler? What if I cannot position centrally, can two bridges be used or maybe some sort of repeater? I have the same problem with WiFi and get around this by using WiFi repeaters.

johnnyp78

Put the bridge where it’s most likely to reach the trvs. Lots of advice on this forum if you do a search. Only one bridge per account I’m afraid, no extenders.

Notascoobie

I have a Worcester Bosch 38 cdi and I can confirm that it doesn’t use Opentherm, but rather it’s own language which I believe is ems? Anyway, I originally had a wireless reciever that came as part of the V3+ starter package connected to the boiler, but later discovered this wasn’t capable of intelligent commas with the boiler. I subsequently swapped the wireless reciever for an EU extension kit which DOES communicate with the boiler intelligently using worcesters proprietary equivalent of opentherm. Hope this helps.

Ditsy

Echoing @johnnyp78, double-check what your boiler supports. I'm definitely not an expert, but I've read that Worcester Bosch only offers EMS which is a proprietary digital connection that is not the same as OpenTherm. Perhaps you have a newer boiler that does support OpenTherm and the information I read is out of date, but probably worth re-checking.

Tado do support some Worcester Bosch boilers but I think you'd be configuring the "Worcester HT-Bus" connection mentioned in some of the Tado installer manuals, not an OpenTherm one.

Northgate

@Notascoobie I have a Greenstar 37CDi and have connected the + & - terminals of my EU wireless receiver (EK)

to the BB terminals of the ST19 connector of the boiler. I have also put a wire link between Lr and Ls of the boiler.

When I raise the temperatures of the Tado smart TRVs and the Tado Wireless Temp Sensor, my Tado app shows that heat is being called for but the boiler doesn’t spring into action. I don’t see the heat led light up on the EK either (not sure if it is supposed to).

Any ideas what is wrong?

Notascoobie

@Northgate , it’s an Extension kit I’m using, not a wireless receiver. I believe that very recently there was a new wireless receiver released that will communicate with some boilers using opentherm. Worcester Bosch greenstar cdi boilers don’t use opentherm though, and I don’t know if the newly released wireless receiver speaks the language your boiler is looking for.

Notascoobie

@Northgate , it might also be worth confirming that your smart radiator thermostats are assigned to the zone controller, which in your case will be the wireless receiver, and not set as independent.

jamese8

Hi I changed my 42cdi to opentherm. It may well be very similar. Search 42cdi..

Of course wb adamant it won’t work, but it does. They should be ashamed as they should be forced to accept opentherm standards as I believe they have in eu?

I have a wired v2 room thermostat so no issue with any Tado Uk version wireless bridge oprntherm limitations

Northgate

@jamese8 That sounds interesting… I wired my Greenstar 37CDi boiler exactly the same way as you did. The only difference is I am using the EU wireless receiver which I bought to replace the UK one that came with the Starter Kit V3+. This is the kit which has the Wireless Smart Thermostat. The only way I can get the boiler to spring into action is if I press the button on top, the boiler then stays on 24/7 unless I press the button again.

I note you are using a wired thermostat V2 and not the wireless one. Maybe that is my problem.

Northgate

OK, I found the problem… my heating is now working correctly. I didn’t know I needed to assign the rooms to a zone controller! I saw the settings in the app and clicked on it by chance and discovered this was what was missing.

I later found a full explanation on the matter here… https://support.tado.com/en/articles/4689126-how-does-tado-control-heating-zones-how-can-i-change-the-zone-controller-of-a-room

So… if you have a Greenstar 37CDi (or other number) classic boiler and want to connect it via the BB terminals to the Tado EU version wireless receiver, make sure you put a wire link between Ls and Lr on the boiler, and make sure you assign everything you want to call heat with to the EU wireless receiver as per the previous link.

Thank you to you all for your help.

jamese8

https://community.tado.com/en-gb/discussion/15638/digital-ems-opentherm-connection-worcester-bosch-42cdi#latest

jamese8

thats what I did with my 42cdi

moedeeb

I am just about to upgrade from an ond bosch 24 cdi to a new 36CDI. Currently running a UK wireless extension kit which is working fine. Reading all the above it appears that if I buy an EU receiver from Tado i will be able to wire directly to the digital side of the receiver and boiler and take advantage of opentherm. Am I correct in this assumption and is it worth the £90 i will need to spend in terms of any difference in efficiency??

Thanks in advance

Northgate

That is correct. The boiler runs more smoothly, like driving a car gently instead of hard acceleration and sharp braking.

igottado

Hi @Notascoobie @jamese8 , sorry to revive old thread but I am in a similar boat. While I have the will and appetite to learn - I have not opened the boiler before.

My boiler is WB Greenstar 38CDI combi classic. so similar to yours..

I have an existing set up of black tado wireless kit and I have just bought the EU wireless receiver and plan is to replace the existing UK wireless receiver to benefit from opentherm/EMS cost efficiencies..

Plan of action:

1. turn off mains power
2. open boiler casing - two screws at the open - unclip at the top
3. slide the while plastic clip down and lower electric box
4. Unscrew three screws to open the connections cover
5. Unscrew cables from Lr and LS to B and B - order does not matter
6. Add a link cable between LR and LS in the boiler - Question - do i need to buy this short cable? where can i get it?
7. Move the other end of these wires from UK wireless to EU wireless + and -. Order does not matter
8. Remove the EU power supply cable from Supply N and L as boiler will provide the power
9. refit boiler connections/cover
10. Power everything up
11. Assign zone controller of EU wireless receiver to the existing Tado thermostat
12. Change config on thermostat so it is using EMS connection - contact support to do this.

Does this sound solid?

Northgate

I didn't need to contact support, the boiler knows when you have connected the two wires to the B terminals.

igottado

I have run into slight issue with power supply. As you can see my LS connection on boiler has grey and black cable and there is an additional cable blue cable in N.
I believe blue N cable and Brown or grey on Ls were powering the UK receiver.
All four are part of one white sleeve. when I moved that sleeve near B and B connections I only connected LR AND Ls cable in the B and B and put cap on cable that was on Blue Ns.
This resulted in receiver not getting any power.
I plugged the EU plug and have temporarily connected to an external power supply.
the boiler is working as expected but I want to change it to so power is received from boiler as before.
Any idea of what I need to do?

igottado

20230404_162142.jpg

here is the picture of how it was originally

hawkman

Hi @igottado, did you ever get this working as expected with bus power? I’ve run into the same problem, when I’d expected from information I found on here that the receiver would be powered from the EMS bus, but it doesn’t turn on unless plugged into the wall. (It does function perfectly once plugged in, but, it’s really suboptimal in various ways.)

johnnyp78

If it’s not taking power from the digital connections, why don’t you just use l and n on the boiler spur? It’s what you would do with an Opentherm connection.

hawkman

That’s probably what I will end up falling back to, @johnnyp78 — I’d been thinking it myself, but it gives me much more confidence seeing you independently recommend it. Appreciated.