Worcester Bosch Greenstar 25i ErP boiler

thebiglebowski

Moved into new house about 6 months ago and it has a Bosch 25i combi boiler and had a Hive thermostat fitted. The Hive was just the thermostat with wireless receiver but no hub.

I've bought a V3+ wireless starter kit as I read the Bosch doesn't support opentherm for the modulation. Then followed the instructions for replacing the Hive as per the app.

N > N

L > L

L > CH Com (link connection)

CH NO > CH NO

The heating is being triggered ok but I'm finding that it is either dropping well below the target temp before switching on and then overshooting the temp before switching off.

Does the thermostat learn how long it takes to heat or is this just a quirk of Tado? (the Hive was good at keeping a uniform temp though)

Is there any benefit to using opentherm or the boiler modulation and if so is it possible to set this up with the V3+ wireless kit?

dchao

I have the same boiler, the promlem is not the boiler, but with Tado cloud servers, when the weather is cold, like the last few days, the servers have to process more requests, so the instructions to turn on or off the boiler will get severely delayed, depending on the server load. When the weather is not that cold, the scheduling speed is back to normal.

What I don’t understand is why Tado will not adding capacity to their servers, since they are adding a lot of new X users on to the system. This problem has been going on for months.

thebiglebowski

Ah that's disappointing, seems strange that they wouldn't manage the temp control locally and just use the cloud servers for the analytics stuff. Problem I have is that the house loses heat so quickly that within 1hr it drops 3c if it's cold out.

It seems to be feathering as well, it turns the heating on for 10mins and then off for a while and then back on again for 10mins so never holds the target temp.

Think it's going back for a refund tomorrow :(

dchao

That's because you didn't install any wireless temperature sensor upstairs. This is not a fault of Tado, but common to all TRV's. Because the temperature sensor is inside the valve and located far too close to the radiator itself, that's why you see a lot of false triggerring (feather). By installing a seperate temperature sensor away from the radiator and windows, your room temperature can be more accurately controlled.

thebiglebowski

I don’t have any TRVs installed. The thermostat is in the same place as the Hive one which didn’t flip-flop

policywonk

That boiler runs in EMS BUS or E-BUS directly but you'd need to swap the wireless receiver for an EU version, or get the old UK BU prefixed version off ebay. Both support that digital protocol. Tado calls it HT-BUS.

We live in a building from 1837, cold as ever and far out in rural territory with low Internet speeds. We tried many different solutions, including Hive, Horstmann, Wise. The Tado v3 system is not ideal but- we found after many trials- more reliable than the others in controlling the boilers (we have three). In the hardest winter days we haven't experienced delays. It isn't a simple decision in old buildings.

thebiglebowski

cheers, have ordered a BUxxxx serial numbered extension kit off ebay.

policywonk

I suspect that the original fitter couldnt be bothered to get this boiler to run in its most efficient mode because the instructions are complicated. You will need three sources of information:

1. Greenstar's installation guide. Greenstar 25-30 Si Compact ErP Installation and Servicing Instructions | Worcester Bosch - look at pages 29-32. This describes how the cables need to be routed.
   1. It has three modes of control. Read the pages again and again and trace these lines of logic.
      1. The boiler can be fired in dumb on-off mode, switched by mains voltage.
      2. The boiler can be fired in E-BUS mode with the internal optional programme (fitted to the faceplate) controlling everything.
      3. The boiler can be fired in E-BUS mode with an external E-BUS controller. This is where Tado comes in.
   2. In fitting the E-BUS mode you have to make sure that small briding loops are added, or removed, in accordance with those instructions given in (1) above.
2. Tado. IContact their sales team. Give them a full description of your home. Let them know if there are zone valves, a hot water tank, how many thermostats - and whether the latter are wired, or wireless. Let them know you have a BU model of UK wireless receiver close to hand, but you need the rest of the information. Ask for detailed explanation on what is needed to connect and commission the Tado systems with your home and boiler. They will send you the necessary descriptions, and these will refer to a fitment in D07 mode. This is the configuration which needs to be given to the Tado systems to interfsce with what they call HT-BUS (their name for Greenstar's E-BUS, aka EMS-BUS).
3. Thats not enough. Both companies dont seem to both giving full instructions.
   1. If you have a faceplate controller on your boiler, you may need to get instructions to remove it. Come back here and search for 'DT10RF', or Greenstar ErP and you should find many users who described the problems they faced and to your n commissioning it in E-BUS mode, you have to find a way to unplug the ribbon
   2. Research the glitches that others overcame. Make up your mind if you want to go ahead and build a plan, to fit the stuff, taking photos as you go along, labelling wires, etc. In this way, if there is a glitch you can put back what was in place and not freeze the family.

Come back here if you need more help. This can be done with patience, care and attention to detail. It saves money in the running of the boiler.

thebiglebowski

Cheers for that. I did email Tado and the response was more than a bit disappointing TBH, basically a fob off:

"Thank you for contacting us.

tado° has been designed to be easy to use and install yourself. You can find your customised step-by-step instructions in the tado° app, to help you install your tado° devices quickly and easily. 

As an alternative, you can contact a local engineer to help you install your tado° devices"

policywonk

@Emcee Would it be possible to ask Support to provide a more useful constructive response from support, given that this issue is commonly met? I know that some of the team do understand this issue.

policywonk

By the way. Every Tado thermostat is required when placed in relay mode to fire the boiler when it's sensors know the temp had fallen. Having watched mine. They have indeed learned the energy delivery curve of the boiler and can cut early nevus they know the rise will continue even after the call for heat has stopped, but that takes months to formulate. And each time you force it up it changes the algorithm.
So if it isn't producing heat force the support team out of bed and term then you aren't getting heat. They are then required to think, not just to push back.

policywonk

@thebiglebowski . This thread Worcester Greenstar cdi 37 installation — tado° Community has been the most constructive I've seen in getting the implementation right. Let us know if that helps.

@wateroakley. Am thinking of asking a few who have helped with this family to create a baseline install guide to help overcome these hurdles.

thebiglebowski

I binned Tado and went back to Hive this afternoon.

Left the house this morning and heating stayed on despite geofencing being enabled :(

thebiglebowski

@policywonk the extension kit arrived in the post today so the stubborn bu**er in me decided to see if I could get it working.

Was actually very easy to get wired and configured. Extension kit needed a firmware update (31 > 81) but otherwise it was really simple.

The installation warning is fine as it just says that hot water control is disabled/inactive (triggers on flow demand)

policywonk

Hah. Well done. Anything more you need? One of the architecture geeks at Tado has kindly offered to respond to our questions (if we handle them carefully). So come back if you need and will do my best to pass on the request.