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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.

  8. #8
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    @djb61 - Thank you for that detailed explanation. Fits with where I have ended up at the moment (still no UFH as the installation is ongoing.) (& @kevinsmart - Thank you for your input as well.)
    I thought I should capture my understanding of the setup now in place which is (seemingly) working well.
    First of all, the system is setup for X-Plan with a Normally Open (NO) 2 port valve on the CH and a Normally Closed (NC) 2 port valve on the HW. The Xclusive is set as follows: P001 - 1 (Xclusive System boiler + cylinder), P081 -3 (not specified in manual as to what this setting means), P070 at 100% (cylinder is rated much higher than the 30kW boiler maximum output).
    X13 pins 4 & 5 are connected to the cylinder NTC *AND* in parallel to a BDR91. The BDR91 is switched by Evohome for HW demand. When the BDR91 is ON, the connection is open i.e. the connection is to terminals A & C. This connects the Xclusive to the NTC only.
    X12 is connected to the Evohome OpenThem for CH control only.
    All scheduling in the Xclusive is off (i.e. P040 & P087 set to 0). (I also discovered that the plumber had left a jumper cable between X13 pins 1 & 2 which essentially meant there was constant CH demand. The manual supplied with the boiler has a diagram which is a bit unclear and does appear to include this link. However, a diagram supplied direct as a PDF by Intergas does not include the link and I confirmed this on a call with Intergas.) (Based on my experience, these pins could be used to implement frost protection which I may investigate as the boiler is installed in a well insulated (at roof level) loft.
    With no HW demand (as controlled by the Evohome) the system seems to work well with excellent control of room temperatures. Early days but control seems better than just with TPI but difficult to judge as the new system was running with constant CH demand (owing to jumper cable between X13 pins 1 & 2) for the first week meaning we had very warm towels at all times.
    When Evohome calls for HW demand, the boiler controls (via X4 pins 1 & 3) the opening of the NC valve via the high limit lock out stat, which in turn closes the NO CH valve. The boiler then works flat out (in theory but I need to try to confirm the actual output). After a short time, the Evohome will see the temp has risen to the setpoint and stop the demand. Should the Evohome not behave, the Xclusive cylinder NTC should mean the boiler itself stops the demand.
    I think it might be good to use the other bit of the dual high limit stat to further reduce the risk of HW demand when the tank is at temperature. The plumber disconnected the secondary stat so it is only working as a high limit lock out. Im tempted to have this reinstated and just set to maximum (circa 65c). However, Id prefer to do this on the 24V DC side (i.e. by closing X13 pins 4 & 5 as the BDR91 does but that would mean mixing 240V AC and 24V DC in the same component which I am not so keen on. (Although that is exactly the setup inside the BDR91)
    I have the CH side set to 80% of max output and a flow temp of 50c. Some more calculations need to be done here and I also need to finally get around to building an ESP8266 temperature sensor for flow and return readings. (And if anyone has read this far, I'd be interested in being pointed to reading material around temperatures, temperature differentials, flow rates, etc. in a system like Evohome where each zone is doing its own thing. I suspect it gets even more interesting when you have to calculate for a hydraulically separated UFH mixing valve with its own pump and different zones doing different things there too. No sarcasm intended; I'd really like to get my head round this stuff.)
    The HW side is set to 100% output with a max flow temp of 85c. The boiler is set to 60c for HW tank temperature. The Evohome is set to 55c for HW currently as it overshoots to around 57c. Again, some minor tweaking here but Legionella dies off pretty quickly at 57c so not too worried.
    Next adventure will be the UFH setup, hopefully before Christmas.

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