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Ebus on Vaillant Ecotec Plus 831 Combi & V3+ Wireless Starter kit

Spot
Spot ✭
in General Questions & Topics

10 years ago I had a Tado installed on this boiler & VRT360f, this was wired for ebus. I initially had Tado system on subscription, and it was getting quite expensive to change to ownership, so I switched to Hive (bad decision).

Anyway I have just got myself the V3+ starter kit and have installed this wired for normal RT control which is ok.

What would be required to change the current V3+ wiring to ebus control?

vaillant vrt wiring.jpg

This was the original VRT wiring, there is no longer a VRT module connected to ebus, just the V3+ Wireless receiver connected to 345 as per instructions.

Answers

  • eezytiger
    eezytiger ✭✭✭
    edited February 14

    I've had Tado V3+ installed with my Ecotec 831 Plus combi for 3.5 years. Twice I've tried connecting with eBus control, but each time the operation has been disappointing and I've reverted to relay control.

    The problem is that the boiler is overpowered for my heating needs and Tado requests an impossibly low flow temp (e.g. 33C) that the boiler quickly overshoots, causing it to shut down prematurely, run the pump for another five minutes and then repeat the cycle. With relay control the boiler continues running until Tado switches it off rather than due to thermal cutout.

    My flow and return temps are still quite efficient with relay control, but not as low as 33C for long on the flow.

    Oh, and here's a photo I took of my boiler innards to illustrate the changes required to switch from relay to eBus….

    Screenshot_20211121-180325_Photos.jpg
  • Spot
    Spot ✭

    Thanks for the info, brilliant.

    Our is a 3 bed semi, 9 rads, so you think its probably not worth switching and leaving it on rt control?

    PS have you a photo of the Wireless receiver wiring?

    Thanks again

    Steve

  • eezytiger
    eezytiger ✭✭✭

    3 bed semi with nine rads here too. All rads have Tado SRTs except the hall, which is where the smart wired thermostat is located.

    I don't have a wireless receiver. I have the smart wired thermostat. Wiring instructions and thermostat configuration when switching between relay and eBus and back again were as described in the Tado support documentation.

    As for the boiler power, I've range rated the boiler down to the minimum output of 9 kW, but so far this winter the house has seldom needed more than 3 kW on average over each 24 hour period - heating is on 24x7. Therefore it has to cycle or it will simply keep raising temperatures. I do not see how eBus control would offer any advantage over relay switching. As I said, it really works rather poorly with my heating system.

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