Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 36

Thread: Opentherm with Evohome

  1. #21
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,002

    Default

    Quote Originally Posted by HenGus View Post
    Forgetting about Evohome for the moment, how then does a condensing boiler work with a 'S' plan system? Presumably, they all have to have some form of HW priority built into them.
    Most boiler can probably deal with HW priority but they need to be wired and controlled with all the stuff that allows that. My isn't. So prior to the OT bridge, the boiler just fired up and reached maximum flow temperature as set on the boiler. The motorised valves just decided where to send that heated water. So when there was CH requirements, the HW recharge time in the cylinder would suffer. Add evohome and the OT bridge and the S plan still works exactly the same, except that when there is HW demand the OT bridge runs the boiler at max but when there is CH only demand then it tries to run the boiler at the lowest setting needed to fulfil all the CH demand.

  2. #22
    Automated Home Legend
    Join Date
    May 2014
    Posts
    988

    Default

    I am now in contact with an 'Ecotechnician/Heating Engineer'. Further research with answers from those who seem to know is that Evohome/Opentherm works well with Atag boilers (bridge + Ebus adapter); Viessmann 100 (plus HW junction box and bridge) and Intergas (but only single zone). Intergas are looking into the problem but any solution may well require a PCB replacement. At this point, I am really beginning to wonder whether the expense of an open therm connection is actually worth the investment? I await my Ecotechnician's quote with interest.

  3. #23
    Automated Home Lurker
    Join Date
    Mar 2016
    Posts
    4

    Default

    I have just had a Evohome installed to my system and have a question re settings required on the boiler PCB. I have Vaillant ecotec plus 630, previosuly with a Vaillant VRC61 wiring centre. The installer followed the following instructions,I got from previous posts on here, to get the VR33 module installed. It all seems to be working, albeit still in learning mode - seeing high boiler temp demands.

    1.install vr33
    2.connect x32 to x31
    3.connect cable that was connected to x31 to the other connector on the vr33
    4.disconnect 230v control
    5.Ensure 24v RT and 230v are linked
    6.wire the r8810 to the T0 terminals on the vr33

    The 2 points I have a question about are 3 and 5.
    3. There wasn't a connector attached to X31. We have assumed this was ok and just ignored this step
    5. Ensure 24v RT is linked. On my boiler there are 3 terminals, marked 7, 8 and 9 for the 24v control. Which ones should be linked, if any? The installer linked pins 7 and 9, but D.016 shows 24V DC Heat Mode: 0 / Off - is this ok. The boiler does fire up, but will this affect anything else?

  4. #24
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,002

    Default

    The vr33 allows the ebus signal to be further passed down to any module that might have been previously connected. Most installations won't have anything connected to X31.

    It's interesting that you have linked 7 to 9. 7 8 9 are pins not used in the UK but are for the analogue non ebus controls. By connecting pin 7 to 9 you are effectively telling the boiler flame to be off.

    Are you certain that the boiler is firing via the OT bridge? In which case you may just have told me why I couldn't get my boiler to fire via OT. My Vaillant 430 too didn't have the 24V RT connection. I without linking pins 7 to 9, if I just linked pins 3 and 4 (230v) then my boiler would constantly fire as though it was being fired via an external control. So if you would please confirm if your boiler is indeed firing up via the OT then that would be great. Pressing the button on the OT bridge should fire the boiler up.

    Others with the 24V RT should be able to confirm what they see on the D.16 menu.

  5. #25
    Automated Home Lurker
    Join Date
    Mar 2016
    Posts
    4

    Default

    I can confirm that if I press the button on the OT bridge the boiler does fire up. I am seeing a demand for 90 degrees whenever ch or dhw is required, but hopefully still in learning mode as only been installed for 1 day. When no demand then boiler switches off.

  6. #26
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,002

    Default

    Excellent, i will put this jumper between 7 and 9 and report back. I have seen various requested flow temperatures between 46 and 90, so would be good to compare.
    If the others can say what value they see in D.16 that would be good too, because at the moment its set to flame off.

    Vaillant 7-8-9 terminal is a potentiometer that gradually changes the voltage from about 11V (off) to 21V DC (full throttle) to regulate heating. The 240V connector are on pins 3 and 4; they are normally bridged with a wire, which means that this 3-4 “switch” is always on, and heating may be controlled through a room thermostat on 7-8-9. However, if you disconnect the room thermostat (i.e., all 7-8-9 wires are in the air, which means ON), the heating is controlled only through 3-4. And that is what I was missing.
    Last edited by bruce_miranda; 26th October 2016 at 04:08 PM.

  7. #27
    Automated Home Jr Member
    Join Date
    Mar 2015
    Posts
    45

    Default

    When I installed the module on my boiler I removed the existing 230V connection that was wired to the BDR91. I connected the VR33 to the expansion board on the side (for me, X31). I also had to reinstate a jumper on the 24V RT connection (for me this was X100, coloured white, and labelled RT24).

    D.016 on mine says "controller 24v dc: heating mode 1n" if that helps!

  8. #28
    Automated Home Lurker
    Join Date
    Mar 2016
    Posts
    4

    Default

    StuartG, we do not gave the 24v RT connection, instead we have 3 pins 7,8 and 9 where the burner off and 24v RT are on the newer boards. I have a Ecotec pro 630 which is about 7 years old.

  9. #29
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,002

    Default

    @sznichol if your boiler is firing up then I wouldn't worry. But because you jumped between 7 and 9 you get D.16 as 0. If you jump between 7 and 8 you will get D.16 as 1.
    I don't know if you should do that or not. I'm going to try both and see if there is any difference.

  10. #30
    Automated Home Legend
    Join Date
    May 2014
    Posts
    988

    Default

    I have at last found an ecotechnician that is keen to work with me to provide an Opentherm solution with an Atag boiler. That said, I am struggling with a couple of things which are the costs/benefits of a 250 additional cost for an EBus to Opentherm converter and Opentherm bridge, and getting confirmation that the Atag Opentherm connection can cope with multiple HR92 zones? FWiW, I finally got confirmation from the guys at Intergas that their boilers do have an issue which is under investigation in The Netherlands.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •