Vaillant Thermostat Communication Fault Question

Discussion in 'Plumbers' Talk' started by royc, Apr 10, 2013.

  1. royc

    royc New Member


    My Vaillant EcoTech boiler is connected with Vaillant thermostat 350f.

    Recently the thermostat is constantly reporting "communication error, failed to connect with heating generator", similar to the image here:

    The manual it says this about this type of error: "Cable defective, plug connection not correct" and that's it.

    I've already made a service call to a Vaillant engineer however was wondering if it is something I can fix myself as these calls are quite pricey.


  2. petertheplumber

    petertheplumber New Member

    Have you checked battery in stat?
  3. royc

    royc New Member

    Yes I have, this is brand new thermostat 350f with out of the box batteries
  4. royc

    royc New Member

    Just wondering if it might be the PCB and is there a way to verify this myself?
  5. sam spade

    sam spade Active Member

    If you mean the batteries supplied with the stat, then they will probably be cheap Chinese ones. Swop them for new Duracell.
  6. royc

    royc New Member

    Already done so, it's not the batteries and the manual indicates that it's not the batteries as mentioned above.

    For battries you will have a different error.
  7. royc

    royc New Member

    For those of you who are interested the problem was indeed defective PCB, replacing it solved the problem
  8. petertheplumber

    petertheplumber New Member

    Great thanks for letting us know.;)
  9. atwittsend

    atwittsend New Member

    Hi I had a Vaillant Ecotec2 Plus 838 Combi with a wireless remote VRT350f fitted 3 weeks ago by a Gas Safe fitter. I have the error like above "Communication heat generator" . I contacted the fitter who came out twice and even spoke with a Vaillant engineer who guided him through a few things no avail. I contacted the Vaillant who sent out an engineer who replaced the controller and receiver, he said it was working and was probably interference but 1 hour into the Auto (set time) heating it came up with the same error. I have had 4 engineers out and am now in the situation where the receiver has been wired away from the boiler as they said it's interference....... Still shows up the same fault. (There is a senior engineer attending Monday 07/03/16 .... will let you know how that pans out.)
    Now this fault means that the heating is stuck ON and can only be turned off from the boiler (which is in the loft). surely this has to be a fault with the boiler?? I paid a lot of money for the boiler plus fitting costs, but now don't feel confident with firstly the boiler and secondly with the company, all the times spent leaving work to be home for an engineer etc is now starting to financially add up.

    Anyone any advice please.
  10. Devil's Advocate

    Devil's Advocate Well-Known Member

    Best advice is - let these guys fix it.

    They are on the case.

    Meanwhile chust turn down each rad so's the boiler reduces its output.
  11. Glad its Friday

    Glad its Friday Active Member

    It probably is an interference problem, hopefully the Vaillant guy will be able to sort it. You may need a booster.

    I'm not a fan of all this RF stuff, Hive, Nest etc. If it goes wrong, where do you start in trying to fix it? I would always try and fit a hard wired timer/stat, you could put your boiler in a nuclear bunker and you could still get it to work with a couple of wires coming up through the floor. And just why do we need to control our central heating from 50 miles away...?

    Could be anything in your case wittsend, steel rsj in the loft, double thickness plaster board. Hope it goes ok, let us know. If all fails get running some wires.
    KIAB likes this.
  12. Tony14

    Tony14 New Member

    I had exactly the same problem and fault message on an Ecotec Plus 32 that had just been installed 5 weeks prior to the problem. The 1st engineer diagnosed a faulty PCB but didn't have the part with him so ordered one there and then for another engineer to fit in a couple of days when I was at home again. The second engineer brought the wrong part and then decided the 1st engineer had misdiagnosed the problem anyway and it was a communication problem between the wireless thermostat and the receiving unit. He relocated the receiver unit that was mounted on the boiler to an adjoining wall and left. Problem was still there as he didn't stay long enough for it to heat up properly as that is when the problem occurs. The 3rd engineer I called replaced the PCB and everything was then ok and he stuck around long enough to be sure it had resolved the problem. He also gave me his mobile number in case anything cropped up.

    There is no official sharing of knowledge (database) on user problems between Vaillant engineers who attend and fix boiler problems. Information about failures go upwards to the senior engineers and laboratories but not sideways to the engineers on the ground. The 3rd engineer had formed a local phone group to share knowledge though on problems they had not met before. I really rated the 1st and 3rd engineers I called out and I can partly excuse the 2nd engineer who obviously had a history with comms failure problems but no experience of this particular PCB one. The Vaillant call centre was also very good as well getting an engineer to me very quickly.
  13. KIAB

    KIAB Well-Known Member

    I'm happy with my EcoTec 824 & Vaillant VRC470F, programmable room thermostat with weather compensator, works flawlessly, no need for Hive,etc.:D
  14. izzy_2nc

    izzy_2nc New Member

    Hi do you have picture of the PCB that is has been replaced? i'm not that familiar in this matter and i have the same problem. is it a PCB from Vrt350 or a PCB inside the heat generator? thanks

Share This Page