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Thread: Intergas Xclusiv / Evohome / OpenTherm / UFH

  1. #1
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    Default Intergas Xclusiv / Evohome / OpenTherm / UFH

    I'm a long time lurker and have read a lot of useful information on here; so first of all, thanks for all of those posts. Unfortunately, I find myself facing a steep learning curve after my previous plumber walked off the job just after removing my existing boiler and DHW cylinder. Just for background, I have previously setup Evohome systems to control both CH (rads only all with HR92UKs) & DHW using the Evohome kit with the thermostat in a pocket. The boiler control was just via a BDR91 with additional BDR91s to open individual 2 port valves for CH or DHW. So standard S-Plan with TPI control.

    The new system that will be installed by a new plumber is planned to use X-Plan with OpenTherm bridge. 1st floor is all rads whilst ground floor is wet UFH in three zones. I have an HCC80R (and there will be a further zone added next year for an extension). I am fairly confident this setup will work but neither the new plumber nor I are clear on some things:

    1. Is the OpenTherm bridge the only required control to the boiler?
    2. What combination of thermostats is needed in the DHW cylinder? (The cylinder is a high gain from Joule with a coil rated at 30kW, I think.)
    3. Does there need to be an additional* 2 port valve on the flow to the UFH manifold? If so, how should this be controlled? (For example, by opening the port when running the pump for the UFH?)
    4. The Intergas manual for X-Plan does not include an automatic bypass valve; given that all BDR91s and UFH actuators might be closed, should there be a bypass for overrun flow? If so, any suggestions on best place to put it?
    5. Is there a particular software version I should be running on the Evohome controller?

    * Additional to the normally closed DHW valve and normally open CH valve.

    Genuinely appreciative of receiving as much detail as possible about working setups. I essentially have a green field site with all the bits waiting to be put together. So I want to avoid mis-steps. And also want to have a working heating system again soon.

    Sorry for long post.

  2. #2
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    1. Yes
    2. CS92 sensor and high-limit thermostat controlling DHW valve
    3. NO 2-port that closes when DHW NC 2-port opens. I also stop the UFH pump on DHW heating via a separate BDR91. For additional safety I have a high-limit thermostat that stops the UFH pump on excessive temperature
    4. I have one after my UFH pump
    5. Request 2.00.19.33

  3. #3
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    Thank you for those answers and sorry for my delay in saying thanks; work's been busy.

    Is there an order I need to follow for binding the new setup? The plumbing work is still not completed and so I would like to get the DHW and 1st floor rads working first, then the UFH later. My outline plan is:

    1. Clear bindings for BDR91s (which are all offline anyway)
    2. Add binding for OpenTherm in place of the previous three BDR91s

    I suspect in reality this will mean clearing the binding for the CS92 and starting over with that.

    I'd prefer not to have to start over with the HR92UKs but should I clear those too i.e. do a full reset of everything?

    Can I add the HCC80R for the UFH later, or do I need to do that earlier in the process?

  4. #4
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    Simply change Appliance Control to OpenTherm, you definitely don’t need to touch your HR92s and probably don’t need to touch your stored hot water CS92/BDR91 setup either, but simple to do if needed from Settings->System Devices.

    You can add your UFH zones later.

  5. #5
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    I am missing something in the setup requirements; more help needed please...

    The plumber started the Intergas Xclusive today with both the normally open CH valve and normally closed DHW valve in the open position. As expected, radiators and DHW cylinder were warmed. He then connected the Evohome OpenTherm bridge and configured the settings for X-Plan as per the Intergas manual. I then bound the OpenTherm controller, which seemed to work without issue. I then cleared the Evohome DHW configuration and re-paired the CS92, and was then asked to pair either a 2/3 port valve or DHW only valve. So I have misunderstood something.

    There is no option to say I don't want a DHW valve, which suggests that the OpenTherm side isn't controlling the DHW demand. Is that correct?

    If the OpenTherm side isn't controlling DHW demand then how does Evohome control this? Do I need to use a BDR91 relay? If so, should it be connected in parallel to the Cylinder NTC sensor (Intergas part. no. 065117) connected across X13 pins 4 & 5? The diagram in the manual does seem to show this layout but the plumber is concerned about shorting the two pins in case it damages the circuit board. (The diagram in the manual describes a "Hot Water Timer (option) (Volt free switching)" and seems to indicate that shorting pins 4 and 5 turns off DHW demand.) The plumber did try calling Intergas but there was no answer after 20 minutes or so of waiting, so I'm back to no heating until this is resolved.

    (This is all in advance of the UFH installation.)

    Thanks again for any help!
    Last edited by Jon_Boy; 1st December 2021 at 11:49 PM.

  6. #6
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    You will need 2 BDR91s, 1 for your 2-port valves and the other for your Intergas DHW NTC.

    On a DHW demand, 1 BDR91 opens the DHW valve and closes the CH valve.

    The other BDR91 (also bound with the DHW) removes the short circuit from the cylinder NTC. This switches the Intergas boiler to DHW mode with a higher flow temperature (and usually lower power output to match the cylinder) overriding the OpenTherm 100% demand temperature (e.g. 70C rather than 60C).

  7. #7
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    I have a similar setup, Intergas with x-plan using Opentherm. The only difference is I have an HRE System Boiler not an Xclusive, looking at the Intergas wiring diagrams for x-plan the setup is the same apart from the pin numbers being different on an HRE vs an Xclusive.
    I do have a BDR91 wired set as a DHW valve so that it shorts the pins (9+10 for me, 4+5 for you) when there is no hot water demand, I did however actually wire in the Intergas cylinder sensor along with the high temperature stat as I wasn't sure what would happen if the boiler saw an infinite resistance from an open circuit. To try an summarise that, when there is DHW demand the BDR91 connects the Intergas cylinder sensor and the boiler measures the temp during DHW demand (I put the setpoint on the boiler above that in Evohome so Evohome always cuts the demand before the boiler would) and when Evohome cuts DHW demand the BDR91 shorts the circuit dropping resistance to 0 which the boiler interprets as temperature above its setpoint.

    The only other thing I found which was very badly documented and I don't know if it is applicable to an Xclusive is I had to set the hot water setting on the front panel to "Eco" (hourglass symbol), the manual claims this does nothing on a non combi but without doing that the boiler would never actually go into DHW mode (on my HRE that is indicated by number 6 on the display whilst according to the manual 5 is the highest possible value which is for CH on and heating).

    It was rather confusing to get it working, especially as Intergas didn't even publish any diagrams when I did it back in 2019 but it does work well, I have a 24kW HRE SB with a 210l Megaflo and I have never exhausted the hot water supply when hot water is on from Evohome. I did set the flow temperature on the boiler for DHW mode to 85 degrees to try and get the most benefit from it too.

    Edit: to address the plumbers concerns, you are not "shorting" these pins, as the wiring diagram suggests with the "volt free switching" there is no voltage on these pins at all. The boiler is measuring resistance across the two pins as the cylinder sensor is a thermistor. So as the temperature rises the resistance drops. I even tested the Intergas sensor by hooking it up to a multimeter and holding it in my hand, as it warmed the resistance dropped. So "shorting" the pins just gives a resistance measurement of near 0 which is interpreted as a very high temperature, as there is no voltage output on the pins there is no risk to the board. I did this testing as I wasn't sure if I would have enough cores in the wiring between the boiler and cylinder to connect everything so I considered using fixed resistors at the boiler end in place of the cylinder sensor and therefore needed to know the resistance reading for normal temperatures, in the end I didn't do this as we used the earth core for one of the thermistor cables and earthed the cylinder wiring centre (2 port valves etc) to an earth circuit there instead, my electrician was happy with using the earth core this way since there was no voltage on the core at all.
    Last edited by djb61; 4th December 2021 at 11:33 AM.

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