Help with Evohome / Opentherm / Intergas

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  • paulmiles01
    Automated Home Lurker
    • Jan 2017
    • 5

    Help with Evohome / Opentherm / Intergas

    Hello,

    I wonder if anyone can help, I'm a relative newbie with Evohome and I suspect I've got some of the finer details of my setup slightly wrong. Helpfully the plumber installed the boiler, wired up the opentherm bridge then left :-(

    In essence, I have an intergas system boiler, megaflo tank, opentherm bridge and evohome. My megaflo is controlled by a standalone timer and NOT by the evohome.

    My house is split into 10 evohome zones. With the exception of my lounge, master bedroom and downstairs/upstairs corridor each zone has a single radiator with a HR92UK on them.

    The master bedroom has two radiators and hence two HR92UKs - how do I know which one is acting as the thermostat? The lounge also has two radiators, two HR92UK and a T87RF2033 wall thermostat - how can I confirm that the T87RF2033 is configured correctly? The downstairs/upstairs corridor has two radiators and a further two HR92UKs - these are controlled by the Evohome thermostat.

    Unfortunately I don't have mains gas, but instead I'm connected to a communal LPG gas tank - which I know is fairly expensive.

    My problem is that my monthly LPG gas bills are around £100 which to me seems very high since this last month we've had our log burner running almost continuously to try to drive the costs down.

    I know this is a very vague question, but can anyone recommend some suggestions on how I can understand how/why my LPG bills are so high, and also if there are any specific settings on the evohome/intergas boiler that I should be tweaking.

    My other question, my HR92UKs have all been running for around 6 months, in that time, I've had to change the batteries in one HR92UK twice! Is this normal ? None of the other batteries have failed yet ?

    Of course if there are any other useful details that you need then I would be happy to dig them out.

    If its useful, I now have a couple of weeks of Domoticz graphs which I can share.

    Sincere thanks in advance,

    Paul
  • dty
    Automated Home Ninja
    • Aug 2016
    • 489

    #2
    Originally posted by paulmiles01 View Post
    My megaflo is controlled by a standalone timer and NOT by the evohome.
    I've not read the rest of your post (yet), but I thought that giving Evohome control over the domestic hot water is a requirement of using the OpenTherm bridge?

    Comment

    • paulmiles01
      Automated Home Lurker
      • Jan 2017
      • 5

      #3
      The reason Evohome doesn't control the hot water was that I didn't think I could fit a sensor to the megaflo without hacking away part of the insulation on the tank.

      The plumber was happy enough to fit the additional timer for the hot water - although to be fair it was the blind leading the blind on that.

      Certainly OpenTherm bridge is working in the sense that radiators get hot as per the evohome schedule - no idea if its modulating as it should be though.

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #4
        Originally posted by paulmiles01 View Post
        The master bedroom has two radiators and hence two HR92UKs - how do I know which one is acting as the thermostat?
        That depends on the order in which you bound them during initial setup. The first one bound to the zone becomes the temperature sensor for both. (Since if you read the prompts carefully it asks you to bind the sensor first, and then "additional actuators")

        After the fact, if you don't remember which order you bound them in, there is no way to tell through the UI. So you either need to perform a test or re-bind the sensor. On the Wi-Fi model you can re-specify the temperature sensor by going into system configuration, zone configuration, choose the zone, Temperature Sensor, Remote sensor, then bind the HR92 you want to be the temperature sensor.
        The lounge also has two radiators, two HR92UK and a T87RF2033 wall thermostat - how can I confirm that the T87RF2033 is configured correctly?
        Since the UI doesn't tell you, the best way to confirm you have the correct device bound as the zone thermostat is to place it somewhere cold (like the fridge) or hot (like on top of a hot radiator) for 5-10 minutes and confirm that the reading on the controller responds accordingly. Any other HR92's in the same zone configured to show room temperature should also reflect this reduced or increased reading, although they may lag behind the value reported on the controller by a few minutes, so give them at least 10 minutes to respond.

        My other question, my HR92UKs have all been running for around 6 months, in that time, I've had to change the batteries in one HR92UK twice! Is this normal ? None of the other batteries have failed yet ?
        Doesn't sound normal - so far all mine have lasted about 14-18 months on standard Alkaline's and I still have some that have not been changed yet.

        There's a possibility that particular HR92 has a battery contact problem - see the following thread, especially if brand new batteries only show 2 bars instead of 3:



        It can cause the HR92 to think the batteries are low when they still have plenty of life left. (And can in fact cause it to cut out altogether sometimes)
        Last edited by DBMandrake; 30 January 2017, 06:49 PM.

        Comment

        • HenGus
          Automated Home Legend
          • May 2014
          • 1001

          #5
          They are reports that Intergas boilers have an issue with an Opentherm connection to Evohome. This was confirmed in an e-mail that I received from Intergas Technical Support. Apparently, the issue is that the PCB cannot cope with Evohome's multi-zoning demands due to data flow. The problem is still under investigation by Intergas in The Netherlands and may require a replacement PCB. I don't know if this is relevant to your situation.

          I have 21 HR92s installed and the first HR92 required replacement batteries after about 22 months. Most have lasted over 2 years.

          This is from an e-mail conversation that I had with an Intergas specialist Installer:

          The problem is that the boiler or Evohome (no one really knows which at the moment) doesn't cope with modulating the setpoint with multiple zones.

          My theory is that there is too much data and the boiler PCB can't interact quickly enough with the OpenTherm bridge so it drops its knickers and runs at whatever the maximum setting is.
          Last edited by HenGus; 30 January 2017, 09:40 PM.

          Comment

          • dty
            Automated Home Ninja
            • Aug 2016
            • 489

            #6
            Originally posted by HenGus View Post
            They are reports that Intergas boilers have an issue with an Opentherm connection to Evohome. This was confirmed in an e-mail that I received from Intergas Technical Support. Apparently, the issue is that the PCB cannot cope with Evohome's multi-zoning demands due to data flow.
            I don't see what difference multi-zoning would make. OpenTherm only asks for a single heat figure. The boiler (and even the OT bridge, I would guess) don't know anything about multiple zones.

            Originally posted by HenGus View Post
            I have 21 HR92s installed and the first HR92 required replacement batteries after about 22 months. Most have lasted over 2 years.
            I've had Evohome now for about 4 1/2 months, and 1/3 or so of my HR92s have lost one bar of battery already (which shows as 50% in Domoticz)!!! Perhaps having OpenTherm would help here because the valves would settle to a steady state rather than opening and closing all the time.

            Originally posted by HenGus View Post
            My theory is that there is too much data and the boiler PCB can't interact quickly enough with the OpenTherm bridge so it drops its knickers and runs at whatever the maximum setting is.
            Ah! That would make (some) sense. Although, TBH, the OT protocol must specify a data transfer rate, so Intergas must be able to figure out how quickly it could possible get heat demand messages (i.e. given the size of the messages, and the data rate, how quickly messages would arrive if they were simply sent back-to-back as quickly as possible), and should really have built their PCB to cope with that.

            Comment

            • HenGus
              Automated Home Legend
              • May 2014
              • 1001

              #7
              Sorry, I should have said that I was talking about the Eco RF boiler. This is the update that I got from Intergas Support just before Christmas:

              Quote There is no resolution date for the issue with the Eco PCB at present, we are still awaiting any news on that sorry. Unquote

              Comment

              • paulmiles01
                Automated Home Lurker
                • Jan 2017
                • 5

                #8
                Originally posted by dty View Post
                I've not read the rest of your post (yet), but I thought that giving Evohome control over the domestic hot water is a requirement of using the OpenTherm bridge?
                Maybe my google skills are lacking but I can't find anything to collaborate - can anyone else confirm if this is urban myth or fact ?

                If its fact, any ideas how I can monitor the temperature of my megaflo without hacking the external insulation about ?

                Comment

                • paulmiles01
                  Automated Home Lurker
                  • Jan 2017
                  • 5

                  #9
                  Originally posted by dty View Post
                  I don't see what difference multi-zoning would make. OpenTherm only asks for a single heat figure. The boiler (and even the OT bridge, I would guess) don't know anything about multiple zones.



                  I've had Evohome now for about 4 1/2 months, and 1/3 or so of my HR92s have lost one bar of battery already (which shows as 50% in Domoticz)!!! Perhaps having OpenTherm would help here because the valves would settle to a steady state rather than opening and closing all the time.



                  Ah! That would make (some) sense. Although, TBH, the OT protocol must specify a data transfer rate, so Intergas must be able to figure out how quickly it could possible get heat demand messages (i.e. given the size of the messages, and the data rate, how quickly messages would arrive if they were simply sent back-to-back as quickly as possible), and should really have built their PCB to cope with that.
                  Any idea how many HR92s is too many? presumably since I've got a couple of rooms with multiple rads (and hence multiple HR92s), if I add wall thermostats in these rooms - wouldn't that help reduce boiler communications ?

                  Comment

                  • dty
                    Automated Home Ninja
                    • Aug 2016
                    • 489

                    #10
                    Originally posted by paulmiles01 View Post
                    Maybe my google skills are lacking but I can't find anything to collaborate - can anyone else confirm if this is urban myth or fact ?
                    Look at it from the other direction. If your boiler is taking instructions from the OT bridge, how does the DHW system call for heat? In fact, how does that work in your current setup?

                    Originally posted by paulmiles01 View Post
                    If its fact, any ideas how I can monitor the temperature of my megaflo without hacking the external insulation about ?
                    Can you use the probe that goes in where the immersion heater would go?

                    Comment

                    • HenGus
                      Automated Home Legend
                      • May 2014
                      • 1001

                      #11
                      Originally posted by dty View Post
                      Look at it from the other direction. If your boiler is taking instructions from the OT bridge, how does the DHW system call for heat? In fact, how does that work in your current setup?



                      Can you use the probe that goes in where the immersion heater would go?
                      I have an OSO unvented cylinder with no ports. The HW sensor has been pushed up under the insulation with access via the electrical panel, and it is wired in series with the existing tank thermostats. It's worked well for nearly 3 years.

                      Comment

                      • paulmiles01
                        Automated Home Lurker
                        • Jan 2017
                        • 5

                        #12
                        [QUOTE=dty;30812]Look at it from the other direction. If your boiler is taking instructions from the OT bridge, how does the DHW system call for heat? In fact, how does that work in your current setup?



                        Currently I have a separate Honeywell single zone timer wired into the boiler that manages my hot water.

                        I also have a solar PV iBoost topping up the megaflo on the rare occasion that the sun comes out.

                        Comment

                        • dty
                          Automated Home Ninja
                          • Aug 2016
                          • 489

                          #13
                          Interesting, I was under the impression that a boiler would either take its instructions from OT or from conventional wiring, and not both.

                          Comment

                          • DBMandrake
                            Automated Home Legend
                            • Sep 2014
                            • 2361

                            #14
                            Some boilers have a separate hot water demand input which fires the boiler and boosts the flow temperature to maximum (or a pre-set hot water flow temperature independent from the central heating flow temperature) and this usually fires the boiler as well, and can work in parallel with OpenTherm.

                            It would mean that you always get that high hot water heating flow temperature when there is hot water reheat demand though, regardless of what OpenTherm asks for, although higher flow temperature with simultaneous hot water and heating demand is a problem in general for S-Plan systems.

                            Comment

                            • splin
                              Automated Home Lurker
                              • Feb 2017
                              • 5

                              #15
                              Originally posted by dty View Post
                              I don't see what difference multi-zoning would make. OpenTherm only asks for a single heat figure. The boiler (and even the OT bridge, I would guess) don't know anything about multiple zones.



                              I've had Evohome now for about 4 1/2 months, and 1/3 or so of my HR92s have lost one bar of battery already (which shows as 50% in Domoticz)!!! Perhaps having OpenTherm would help here because the valves would settle to a steady state rather than opening and closing all the time.

                              Originally posted by HenGus View Post
                              They are reports that Intergas boilers have an issue with an Opentherm connection to Evohome. This was confirmed in an e-mail that I received from Intergas Technical Support. Apparently, the issue is that the PCB cannot cope with Evohome's multi-zoning demands due to data flow. The problem is still under investigation by Intergas in The Netherlands and may require a replacement PCB. I don't know if this is relevant to your situation.

                              I have 21 HR92s installed and the first HR92 required replacement batteries after about 22 months. Most have lasted over 2 years.

                              This is from an e-mail conversation that I had with an Intergas specialist Installer:

                              The problem is that the boiler or Evohome (no one really knows which at the moment) doesn't cope with modulating the setpoint with multiple zones.

                              My theory is that there is too much data and the boiler PCB can't interact quickly enough with the OpenTherm bridge so it drops its knickers and runs at whatever the maximum setting is.

                              Ah! That would make (some) sense. Although, TBH, the OT protocol must specify a data transfer rate, so Intergas must be able to figure out how quickly it could possible get heat demand messages (i.e. given the size of the messages, and the data rate, how quickly messages would arrive if they were simply sent back-to-back as quickly as possible), and should really have built their PCB to cope with that.

                              The 'too much data' doesn't make any sense to me and sounds like a fob-off. According to the Opentherm protocol spec V2-2 which has been made public on a blog site, the Opentherm interface is point to point so the only traffic that the boiler will see is that intended for it (and the protocol doesn't include any sort of address information anyway). As far as the boiler is concerned I can't see how a multi-zoned system would make any difference at all as the controller should simply calculate the total heating load of all the zones and modulate the boiler output, and possibly the pump, accordingly.

                              I wouldn't expect any more, or different messages, to be involved than in a single zoned system. At the end of the day it is just a boiler which has one simple job - however the rest of the system is configured - which is to provide the amount of heat the controller specifies and control the pump appropriately (if it has one).

                              In fact that Opentherm document states:

                              There is only one control value defined - data-id=01, the control setpoint. The control setpoint ranges between a minimum of 0 and maximum of 100. It represents directly a temperature setpoint for the supply from the boiler. The slave does not need to know how the master has calculated the control setpoint, e.g. whether it used room control or OTC, it only needs to control to the value. Likewise, the master does not need to know how the slave is controlling the supply.
                              As to messaging rates, the protocol spec specifies the data rate to be 1000b/s (very slow) and that a minimum time of 100ms is required between the end of a response from the boiler to the controller and the next request or command sent from the controller. It is also allowed for the boiler to wait up to 800ms to respond to a command/request. For any boiler control circuitry not built with relays 100ms is an absolute age and should easily be handled with any microcontroller built since the 1970s. Hmm unless it's running Java perhaps.

                              I guess the protocol could have been updated to permit faster messaging but it still wouldn't explain how the boiler could see any difference between single and multi-zoned installations. If Intergas or Honeywell aren't prepared to provide more information or explain what the real issue is, it will need someone with an Arduino (or similar) Opentherm monitor to have a look at what messages are sent by the Evohome in an Intergas multi-zone system.

                              I don't understand why there seem to be so many problems with Opentherm, as, in essence, the main functionality of the interface is trivial - to allow a thermostat/controller to tell the boiler how much heat to produce; all the rest including boiler sensor and status information, fault codes etc. is not required though it may be of interest to a more sophisticated controller. Perhaps the problem is due to the specification not sufficiently specifying the exact behaviour of the boiler in response to commands.

                              Or perhaps because the spec allows 'Transparent Slave Parameters' whereby the boiler can have settable, but unspecified, parameters of which the controller has no knowledge. I guess it's conceivable this could require a controller to send some special messages for the boiler to function correctly, e.g. to extend the standard. I guess this would allow the boiler manufacturer to declare Opentherm compatibility whilst effectively making it only controllable by equipment made by collaborating manufacturers. It seems a bit of a stretch though and it's hard to see what advantage that would provide.

                              Comment

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