Vaillant ecotec plus and ebus

Bigalfie71

Hi there.
I've recently had a Vaillant ecotec plus 835 boiler fitted. I've also just bought a tado v3+ wireless starter kit.
Just going through the installation instructions on the app and it says to wire the wireless receiver to 24v=RT on the boiler. Is this correct as I thought it should be wired to - /+bus for boiler modulation.
Any help would be greatly appreciated

Kissarmy

Unfortunately Tado removed ebus connections from UK wireless receivers. I too was caught out by this but managed to buy an old wireless extension kit which did ebus. Tado have relented on this by selling the EU version on their UK installers website. The EU version does not do hot water. no good for UK system boilers, but as you have a Combi it would work for you. Either return your current starter kit for a refund and order a wireless starter kit for combos from Tado or just buy the wireless receiver for combos. The receiver is currently out of stock but the kit for combos is in stock.
https://uk.installers-shop.tado.com/

johnnyp78

If you ordered this https://uk.installers-shop.tado.com/products/add-on-wireless-receiver-for-combi-boilers they’ve sent you the wrong version.

Bigalfie71

It is the wireless receiver for combi's that I have. Bought directly from tado last week.

Kissarmy

What boiler type did you specify when following the installation instructions. I had a few hiccups to start off with. Had to go way down the list to select 'ecoTEC plus 800 series (Combi)' after that I had no problems.

Bigalfie71

I specified ecotec plus 800 series with timeswitch 150

johnnyp78

24v sounds like a low voltage terminal which could be used for digital connections. Are there + and - terminals as well?

Kissarmy

@johnnyp78 Vaillant ecoTEC boilers have terminals for both 230volt AC room thermostats and 24volt DC room thermostats. There are separate +/- Bus terminals.

johnnyp78

In that case I don’t see any reason why you wouldn’t use the bus terminals. Maybe the app is giving instructions for a low voltage relay connection.

Bigalfie71

I don't see a bus connection on my receiver.

Bigalfie71

My boiler connections

johnnyp78

@Bigalfie71 that’s the uk version of the wireless receiver. You need the eu version if you want digital connections.

Bigalfie71

Ok thanks, looks like i'll need to send it back.

Thanks for all your help.

JayC

Hi. I have the 'new' euro tado wireless receiver fitted to my Valiant ecotec 832 plus (VUW 25/32CS (N-GB)). Despite following tado instructions and wiring into the Bus (10 on the attached schema) I only have hot water. No heating. Ideas/solutions to get digital welcomed (aim is to have Modulating rather than Relay)

Rob

@JayC

For one, for these kinds of requests our support is better suited to help you than the forum.

However, I could not help myself and looked at the tado account that shares your forum-email. I observed the following:

• Settings seem correct. Vaillant eBus selected. Most rooms are able to ask for heat at the wireless receiver (boiler)
• I can read water temperature (for heating) over time inside the boiler, meaning that the eBus connection is working
• Multiple rooms are asking for heat.
• Water temp (for heating) shows a pattern that is common for a boiler when it is replying to a heating request (could also be DHW), with the water peaking at roughly 50 degrees (+/-5). Today starting at roughly 8:30 in your timezone.
• Yet, radiator thermostat do not seem to get hot

One thing though, for your boiler. Please confirm this in your manual, but my documentation says that you have to bridge the 24V RT (relay thermostat) connection when you connect a modulating thermostat to the BUS ports. This might also be the reason it is not working.

If that is not the issue; it is early August. Is your boiler maybe in some kind of summer mode that would prevent it from heating?

Example picture, with the bridge on "24V RT" in place:

Again though, for this kinds of very specific issues, our support is usually the best resource.

JayC

@rob I appreciate you joining in and looking up my account.
I have reset the boiler to factory settings confirming that the external weather sensor is not shown as active. There are no fault codes (history clear too). I have discovered the entry in the manual (attached should you need it for anther customer). Inserted a bridge at 9 (24v). I have heating.

Thank you so much Rob. (I don't seem to be able to adjust the flow rate but maybe 'modulation' takes care of that).