No heating this morning

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  • DBMandrake
    Automated Home Legend
    • Sep 2014
    • 2361

    #16
    Originally posted by Dean View Post
    I'm with BT - going to log the issue with Honeywell and a couple of others such as BDR91 intermittently running for two additional on/off cycles after all zone temperatures have been lowered either scheduled or via mobile app (i.e. way below zone temperatures and no zone is calling for heat) which is wasting energy and gas as the heat is going through the bypass loop as HR92's are closed.
    After you've scheduled the change, or after all the HR92's have actually, definitely closed ? Keeping in mind there will be a random delay of up to 4 minutes from when you initiate the set point change at the controller and when the HR92's will be updated and start to close, and fully closing takes an additional 30 seconds - during that up to 4m30s they can still call for heat, and if the heat demand is low causing an intermittent TPI cycle it can make it look like the boiler has come on after you've turned the heating off, when all that's really happening is the existing TPI on/off duty cycle is continuing for a bit longer.

    If it comes back on again well after 5 minutes then yes you have a problem - I have seen this happen once or twice before, sometimes the spurious relay activation only lasts a few seconds despite my minimum on time of one minute...(minimum on time is not enforced if the heat demand is removed part way through the on period)
    I really wish there was an event logging system in this device which I am sure would also assist engineers that come across problems that records the controller actions, such as BDR91 on/off, zone request change/confirmed, zone temperature etc or even if this information was just sent to Honeywell servers which could be accessed in the online portal/mobile app (which would be preference).
    I'm with you there - there really does need to be more troubleshooting functionality, even if hidden behind a secret expert settings screens. Even zone based heat demand indicators would help a lot in troubleshooting these issues as "unexpected" boiler firings seem to be the most common issue people are trying to troubleshoot.
    Another issue I notice as the controller is directly in my line of sight is that during the hour, the EvoHome Controller Internal Temperature sensor drops by 0.5c for exactly one minute 2-3 times an hour and then back to previous temperature (e.g. shows 19.5c then drops to 19c for one minute then back up to 19.5 again multiple times, also occurs at different temperature settings), with or without heating on, no draughts, various times of the day/night, controller in middle of the room and separate thermometer next to controller shows a stable temperature. At first I thought it was due to the controller trickle charging the batteries, but the same effect is seen out of the base unit.
    I wouldn't worry about that - I see the same thing and always have done. I can clearly see this behaviour in my temperature graphs.

    I put it down to the fact that the built in sensor has a much more frequent "refresh" interval than all other remote sensors. I believe HR92's and DTS92's only send out a temperature update once every 4 minutes, so if the temperature is right on the threshold of changing from one 0.5 increment to another it could only do it at most once every 4 minutes, and statistically speaking it is unlikely to happen, so you don't tend to see these random fluctuations.

    However the built in sensor updates continuously and is updated on the screen every time the screen refreshes - which is at least once a minute (to update the clock) and probably more frequent if updates from other zones are arriving at different times, leading to multiple screen updates per minute so the built in sensor reading has a habit of "toggling" its least significant value if it is right on the threshold because it can update so frequently.
    Last edited by DBMandrake; 4 October 2016, 12:07 PM.

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    • DBMandrake
      Automated Home Legend
      • Sep 2014
      • 2361

      #17
      Originally posted by paulockenden View Post
      Never forget that Virgin was the UK ISP initially very keen to get into bed with Phorm.
      Yep - they also used to return ad/search pages instead of NXDOMAIN errors for DNS lookups for non existent domains - I remember turning that off within myvirginmedia - in fact I suspect it is still on by default for most people even now!

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      • Dean
        Automated Home Jr Member
        • Feb 2016
        • 11

        #18
        Originally posted by DBMandrake View Post
        After you've scheduled the change, or after all the HR92's have actually, definitely closed ? Keeping in mind there will be a random delay of up to 4 minutes from when you initiate the set point change at the controller and when the HR92's will be updated and start to close, and fully closing takes an additional 30 seconds - during that up to 4m30s they can still call for heat, and if the heat demand is low causing an intermittent TPI cycle it can make it look like the boiler has come on after you've turned the heating off, when all that's really happening is the existing TPI on/off duty cycle is continuing for a bit longer.

        If it comes back on again well after 5 minutes then yes you have a problem - I have seen this happen once or twice before, sometimes the spurious relay activation only lasts a few seconds despite my minimum on time of one minute...(minimum on time is not enforced if the heat demand is removed part way through the on period)
        Yes, I had the issue with Gen 2 and was hoping it would go away with Gen 3, but seems to be a Software Issue. Appears to have a mind of it's own and hard to replicate (without any event logging). It happened twice in the past couple of days and multiple times previously (even completely reset, unbound and cleared everything (controller, HR92's, BDR91) to see if it would fix it). Yesterday I had one zone on until 18:00 and heard the HR92 close down, and all other zones were off, but the Boiler relay kicked in at around 18:12 for a few minutes, then off and then again around 18:32 (I have my controller set to 3 cycles with 2 mins min, used to be 6 cycles which also had the same issue)

        Originally posted by DBMandrake View Post
        I wouldn't worry about that - I see the same thing and always have done. I can clearly see this behaviour in my temperature graphs.

        I put it down to the fact that the built in sensor has a much more frequent "refresh" interval than all other remote sensors. I believe HR92's and DTS92's only send out a temperature update once every 4 minutes, so if the temperature is right on the threshold of changing from one 0.5 increment to another it could only do it at most once every 4 minutes, and statistically speaking it is unlikely to happen, so you don't tend to see these random fluctuations.

        However the built in sensor updates continuously and is updated on the screen every time the screen refreshes - which is at least once a minute (to update the clock) and probably more frequent if updates from other zones are arriving at different times, leading to multiple screen updates per minute so the built in sensor reading has a habit of "toggling" its least significant value if it is right on the threshold because it can update so frequently.
        Good to know, just thinking it would affect the learning algorithm with heating on, with constantly dropping 0.5c, but guessing as the display is rounded it's just for display purposes and not the temperature it uses in heating algorithms. Personally I would prefer to see the temperature in 0.1c increments

        Comment

        • paulockenden
          Automated Home Legend
          • Apr 2015
          • 1719

          #19
          It would be nice if Evohome was perfect, but I've come to the conclusion that - despite the niggles - I'm better off with it than without.

          Yes, the boiler firing is illogical. Yes the temps sometimes are half a degree out. Yes there are other niggles too.

          But there's no getting away from the fact that my gas bill is reduced (approx 20%) and more important than that, my house is more comfortable. So I've begun to stop obsessing over the details.

          P.

          Comment

          • HenGus
            Automated Home Legend
            • May 2014
            • 1001

            #20
            Originally posted by paulockenden View Post
            It would be nice if Evohome was perfect, but I've come to the conclusion that - despite the niggles - I'm better off with it than without.

            P.
            I would concur fully with your view. My savings have been in the order of 18% per annum of gas used which, sadly, does not equate to an annual cost saving of 18% (because of standing charges). As an aside, it was pointed out to The Science and Technology Select Committee during its recent examination of the smart meter programme that if consumer savings were at the heart of the smart meter programme, then much higher energy savings could be achieved with a National roll-out of smart thermostats.

            Comment

            • DBMandrake
              Automated Home Legend
              • Sep 2014
              • 2361

              #21
              Originally posted by Dean View Post
              Yes, I had the issue with Gen 2 and was hoping it would go away with Gen 3, but seems to be a Software Issue. Appears to have a mind of it's own and hard to replicate (without any event logging). It happened twice in the past couple of days and multiple times previously (even completely reset, unbound and cleared everything (controller, HR92's, BDR91) to see if it would fix it). Yesterday I had one zone on until 18:00 and heard the HR92 close down, and all other zones were off, but the Boiler relay kicked in at around 18:12 for a few minutes, then off and then again around 18:32 (I have my controller set to 3 cycles with 2 mins min, used to be 6 cycles which also had the same issue)
              As far as I know the controller doesn't directly switch the relay on and off it simply sends an updated duty cycle / demand figure to the relay which handles the switching on and off in a TPI pattern autonomously. So even if you pulled the batteries out of the controller an already cycling BDR91 would continue to cycle by itself for some time until it eventually realised that the controller hadn't been heard for a while and switched to failsafe (or off) mode.

              My hunch is a heat demand message from the controller to BDR91 goes missing (collisions, interference etc) thus when you turn the heating off the the message to say "zero heat demand now" isn't received by the BDR91, which continues on its last known TPI duty cycle. Most likely the current (zero) heat demand is re-sent and on a subsequent transmission the message gets through, then the BDR91 turns off for real. The lost messages also might be between an HR92 and the controller.

              Without more information it's hard to say how much of the wireless protocol is acknowledged and how much is unacknowledged transmissions - I get the impression that some system messages are unacknowledged in the design of the protocol and thus can go missing if there is interference or collisions. For example adjusting the set point directly on an HR92 updating the set point on the controller (local override display) is a message that apparently can go missing - make several adjustments in a row and you'll find one doesn't go through at random - at least I find that. And then the set point on the two devices are out of sync until you next adjust it.

              Another possibility with the BDR91 is if failsafe mode is enabled and it missed some messages from the controller it might drop into failsafe mode (20% duty cycle) until it next hears from the controller then go back off again. I'm pretty sure I've seen the odd behaviour with failsafe mode disabled though so it can't explain all examples of unexplained boiler firing.

              Good to know, just thinking it would affect the learning algorithm with heating on, with constantly dropping 0.5c, but guessing as the display is rounded it's just for display purposes and not the temperature it uses in heating algorithms. Personally I would prefer to see the temperature in 0.1c increments
              As the temperature is rounded to 0.5 degrees the fluctuation that results in the figure jumping back and forth 0.5 degrees is probably in reality only 0.1 degrees or so, but its right on the margin of rounding.

              You can actually get temperatures to two decimal places now using the old V1 Web API - in another thread I posted a small change to the domoticz plugin to take advantage of this, so my domoticz dashboard shows all zone temperatures to two decimal places and without the bogus rounding towards the set point that you see on the controller. After comparisons with another digital thermometer I've come to the conclusion that whilst both decimal places change, true resolution/granularity is somewhere on the order of 0.1 degrees, but that is still a lot better than 0.5 degrees and rounding towards the set point. I sometimes look at my domoticz dashboard from my phone to see what the "real" temperatures are, rather than the sanitised figures that the controller and iPhone app shows...

              I too would love to see 0.1 degree resolution without rounding towards the set point on the controller itself, but somehow I don't think this will happen! It's only a cosmetic issue though, the underlying control algorithms work with the full measurement resolution.
              Last edited by DBMandrake; 4 October 2016, 04:02 PM.

              Comment

              • Dean
                Automated Home Jr Member
                • Feb 2016
                • 11

                #22
                Originally posted by DBMandrake View Post
                As far as I know the controller doesn't directly switch the relay on and off it simply sends an updated duty cycle / demand figure to the relay which handles the switching on and off in a TPI pattern autonomously. So even if you pulled the batteries out of the controller an already cycling BDR91 would continue to cycle by itself for some time until it eventually realised that the controller hadn't been heard for a while and switched to failsafe (or off) mode.
                Many thanks, didn't realise that, this certainly clears things up.

                Originally posted by DBMandrake View Post
                Another possibility with the BDR91 is if failsafe mode is enabled and it missed some messages from the controller it might drop into failsafe mode (20% duty cycle) until it next hears from the controller then go back off again. I'm pretty sure I've seen the odd behaviour with failsafe mode disabled though so it can't explain all examples of unexplained boiler firing.
                There is no Red LED showing when this occurs, if BDR91 has gone into failsafe mode, would it show the Red LED?

                Comment

                • DBMandrake
                  Automated Home Legend
                  • Sep 2014
                  • 2361

                  #23
                  Originally posted by Dean View Post
                  There is no Red LED showing when this occurs, if BDR91 has gone into failsafe mode, would it show the Red LED?
                  I don't think so.

                  A couple of times I have deliberately let the batteries run right down on the controller by leaving it off the dock, and I don't recall seeing the red LED - the only time I have seen the red LED is flashing when unbound or during binding. But keep in mind I only enable failsafe mode in winter.

                  I might enable failsafe mode and take the batteries out of the controller for an hour to see what happens though - you've got me curious now!

                  Comment

                  • SplanK
                    Automated Home Jr Member
                    • Jul 2016
                    • 16

                    #24
                    Hi all,
                    I'm here to report that my Gen3 did exactly as OP's post. Seemed to turn on my zones this morning but never switched them off.

                    I thought it was lagging 1 hour behind but when that time had passed I then spied the time, it was out (but updated itself when I went through the options)...

                    I have rebooted it now using the "off the wall mount, batteries out" method and allowing it to settle down (although as above, some zones are taking their time to re-sync with the controller!)

                    Comment

                    • HenGus
                      Automated Home Legend
                      • May 2014
                      • 1001

                      #25
                      Originally posted by SplanK View Post

                      I have rebooted it now using the "off the wall mount, batteries out" method and allowing it to settle down (although as above, some zones are taking their time to re-sync with the controller!)
                      You can speed up the re-synch process with a push/release on the menu button on an HR92 in each of the zones.

                      Comment

                      • SplanK
                        Automated Home Jr Member
                        • Jul 2016
                        • 16

                        #26
                        Ta, spotted that a few seconds ago..... to lazy to get out of my office chair now though

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