Tracking down random boiler demand with Evohome

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  • Ubarrow
    Automated Home Jr Member
    • Oct 2014
    • 24

    #31
    Originally posted by The EVOHOME Shop View Post
    This could well be the fact you have bound your system incorrectly or double bound an item. I've seen this happen a few times with my customers and all have been because they have bound something incorrectly or rushed the binding process, especially using guided config. Once I have walked them through a complete rebinding process this has been eliminated.

    I would suggest a rebind of the system, be sure to unbind everything completely and rebind everything maliciously.

    I only normally technically help my own customers, but seems you have had some issues so maybe give me a call and I will help - 07884 110955.

    Thanks,

    Richard
    "rebind everything maliciously." It's not that bad surely?

    Comment

    • Wallyİ
      Automated Home Sr Member
      • Jan 2015
      • 53

      #32
      I'm sure he meant meticulously...

      Comment

      • The EVOHOME Shop
        Site Sponsor
        • Dec 2014
        • 483

        #33
        Originally posted by Wallyİ View Post
        I'm sure he meant meticulously...
        LOL, I did... Even I am not perfect!

        Comment

        • erik
          Automated Home Guru
          • Feb 2015
          • 244

          #34
          Hi, I'm Erik from the Netherlands. Registered here to share my experiences. Been testing/monitoring Evohome for over a year now. My theory is that Evohome right now is fundamentally broken, but only in houses with good isolation or big radiators or where there's no big offset between outside temperature and requested room temperature. I hope Honeywell is able to fix it with new firmware.

          First I'll describe normal behaviour. Normal behaviour happens when I use an old skool Honeywell Round on/off. Let's say the room temperature is 14. I set the Honeywell Round to 17. At first, it sends a continuous ON signal to my boiler. When the room temperature hits about 16, it will no longer be ON continuous, but it will start switching ON or OFF in 10 minute cycles. For example: 3 minutes on, 7 minutes off, 2 minutes on, 8 minutes off, etc. etc. Basically, the Round is constantly calculating/guessing how much heat per 10 minutes it needs to request from the boiler. If it asks too much, there might be an overshoot. If it asks too little, the room won't reach the requested temperature. There's a minimum-ON-time of 1 minute. If the room temperature has gone slightly over the requested temperature, the room is well isolated, and it's not too cold outside, Round will calculate that it requires no more heat from the boiler. So, it makes an important decision: it will NOT request heat from the boiler for at least 10 minutes. After 10 minutes, it will make this decision again, etc. After skipping 1, 2 or 3 cycles, it reaches the point where the room might cool down below the requested room temperature and it will start requesting heat from the boiler again.

          So that's normal behaviour: if temperature is way too low, go ON continuously. If temperature is a little low, switch between ON and OFF in 10 minute cycles. If temperature is high, stay OFF for a while. Skip one or more 10 minute cycles. Start using ON/OFF cycles again when temperature might be going below the requested temperature soon. The Honeywell Round is ableto keep my room temperature very close to my requested temperature. It performs very well.

          Now Evohome... The BDR91 works almost identically as the Honeywell Round. If temperature is way too low, it goes ON continuously. If temperature is a little low, or equal to the requested temperature, it switches between ON and OFF in (by default) 10 minute cycles. Minimum-ON-time (by default) is also 1 minute. However, here comes the difference:

          when temperature is high, it NEVER skips a 10 minute cycle. I've been monitoring it A LOT (hours and hours) and I've NEVER EVER seen it switching a 10 minute cycle. That means it goes ON for at least 1 minute, every 10 minutes. If your house is well-isolated, or if you have big radiators, or if outside temperature is only a little below requested room temperature, this 1 minute of heat per 10 minutes WILL increase the temperature in the room. This means that if Evohome keep asking for heat every 10 minutes, it will slowly cause a huge overshoot. There's a limit to this behaviour however:

          When using Evohome in thermostat-modus (only Evohome+BDR91, no radiator valves), it will continue slowly heating up the room untill the temperature reaches 1.5 degree above the requested temperature. After that, it will finally stop requesting heat.

          When using Evohome in zoning modus (Evohome+BDR91+HR92s), it will continue slowly heating up the room untill the temperature reaches about 0.7 degree above the requested temperature. After that, it will finally stop requesting heat.

          This process of slowly heating up above requested temperature can take 2 hours easily. It's not a short accidental overshoot. It's a continuous, well orchestrated slow build up of overshoot on overshoot on overshoot. It's a huge bug in my opinion.

          Once it has FINALLY stopped requesting heat, it won't start requesting heat again untill the temperature falls all the way back to slightly above your requested temperature. So this means a room temperature that will be falling about 1.5 or 0.7 degrees. This can easily take 2 or 3 hours. A room that's not being heated for 2 or 3 hours, feels very uncomfortable, so this is very unwanted behaviour. The old skool Honeywell Round is performing well and able to keep a very constant temperature at my place, Evohome is performing very bad and slowly creating huge overshoots and then cooling down again.

          Some people have suggested to put my requested temperature a degree lower in Evohome, to compensate for this Evohome behaviour. This is not a solution. Yes, it will prevent Evohome from heating up the room too much, but it won't prevent Evohome from letting it cool down too far afterwards.

          If the 1 minute of heat per 10 minute cycles is not enough to increase the temperature of your room, then there's no problem. You won't get these huge overshoots. So you might not recognize this behaviour. But if it IS enough, then you'll notice Evohome requesting heat from your boiler EVERY 10 minutes, even when the temperature in the zone is already way above the requested temperature. This will go on untill it reaches 0.7 or 1.5 above the requested temperature.

          I've factory re-set and correctly re-binded countless times already. It makes no difference.

          I've been in contact with Honeywell and they're going to try and reproduce the behaviour. I hope they will be able to reproduce and create a fix for it... We will wait and see.

          Comment

          • erik
            Automated Home Guru
            • Feb 2015
            • 244

            #35
            Reason I posted this here is because the problem corresponds with the thread starter description. A heat demand every 10 minutes, even though the room is already above setpoint. It's fine that it's trying to maintain the temperature and prevent a drop below setpoint. But when it's way above setpoint and when it's not cooling down, then it should stay OFF for a while, instead of increasing temperature even further.

            Also, it's not a matter of Evohome needing more time to 'learn'. I've had it running the exact same set-up for weeks, 5 or 6 weeks for example. It never learns. It continues to show the same behavior.
            Last edited by erik; 21 February 2015, 08:30 PM.

            Comment

            • erik
              Automated Home Guru
              • Feb 2015
              • 244

              #36
              Also, the communication between all components is always Excellent. There's no errors in the log either.

              Comment

              • Wallyİ
                Automated Home Sr Member
                • Jan 2015
                • 53

                #37
                Originally posted by erik View Post
                Also, the communication between all components is always Excellent. There's no errors in the log either.
                Welcome to TPI Erik...

                It's built into the firmware and here to stay...

                If Honeywell would just give users the option to enable/disable it...

                But from what I gather from the experts here...and from reading between the lines...

                This very expensive 'smart' device will not be eligible for a firmware upgrade...

                Comment

                • top brake
                  Automated Home Legend
                  • Feb 2015
                  • 837

                  #38
                  Originally posted by erik View Post
                  Hi, I'm Erik from the Netherlands. Registered here to share my experiences. Been testing/monitoring Evohome for over a year now. My theory is that Evohome right now is fundamentally broken, but only in houses with good isolation or big radiators or where there's no big offset between outside temperature and requested room temperature. I hope Honeywell is able to fix it with new firmware.

                  First I'll describe normal behaviour. Normal behaviour happens when I use an old skool Honeywell Round on/off. Let's say the room temperature is 14. I set the Honeywell Round to 17. At first, it sends a continuous ON signal to my boiler. When the room temperature hits about 16, it will no longer be ON continuous, but it will start switching ON or OFF in 10 minute cycles. For example: 3 minutes on, 7 minutes off, 2 minutes on, 8 minutes off, etc. etc. Basically, the Round is constantly calculating/guessing how much heat per 10 minutes it needs to request from the boiler. If it asks too much, there might be an overshoot. If it asks too little, the room won't reach the requested temperature. There's a minimum-ON-time of 1 minute. If the room temperature has gone slightly over the requested temperature, the room is well isolated, and it's not too cold outside, Round will calculate that it requires no more heat from the boiler. So, it makes an important decision: it will NOT request heat from the boiler for at least 10 minutes. After 10 minutes, it will make this decision again, etc. After skipping 1, 2 or 3 cycles, it reaches the point where the room might cool down below the requested room temperature and it will start requesting heat from the boiler again.

                  So that's normal behaviour: if temperature is way too low, go ON continuously. If temperature is a little low, switch between ON and OFF in 10 minute cycles. If temperature is high, stay OFF for a while. Skip one or more 10 minute cycles. Start using ON/OFF cycles again when temperature might be going below the requested temperature soon. The Honeywell Round is ableto keep my room temperature very close to my requested temperature. It performs very well.

                  Now Evohome... The BDR91 works almost identically as the Honeywell Round. If temperature is way too low, it goes ON continuously. If temperature is a little low, or equal to the requested temperature, it switches between ON and OFF in (by default) 10 minute cycles. Minimum-ON-time (by default) is also 1 minute. However, here comes the difference:

                  when temperature is high, it NEVER skips a 10 minute cycle. I've been monitoring it A LOT (hours and hours) and I've NEVER EVER seen it switching a 10 minute cycle. That means it goes ON for at least 1 minute, every 10 minutes. If your house is well-isolated, or if you have big radiators, or if outside temperature is only a little below requested room temperature, this 1 minute of heat per 10 minutes WILL increase the temperature in the room. This means that if Evohome keep asking for heat every 10 minutes, it will slowly cause a huge overshoot. There's a limit to this behaviour however:

                  When using Evohome in thermostat-modus (only Evohome+BDR91, no radiator valves), it will continue slowly heating up the room untill the temperature reaches 1.5 degree above the requested temperature. After that, it will finally stop requesting heat.

                  When using Evohome in zoning modus (Evohome+BDR91+HR92s), it will continue slowly heating up the room untill the temperature reaches about 0.7 degree above the requested temperature. After that, it will finally stop requesting heat.

                  This process of slowly heating up above requested temperature can take 2 hours easily. It's not a short accidental overshoot. It's a continuous, well orchestrated slow build up of overshoot on overshoot on overshoot. It's a huge bug in my opinion.

                  Once it has FINALLY stopped requesting heat, it won't start requesting heat again untill the temperature falls all the way back to slightly above your requested temperature. So this means a room temperature that will be falling about 1.5 or 0.7 degrees. This can easily take 2 or 3 hours. A room that's not being heated for 2 or 3 hours, feels very uncomfortable, so this is very unwanted behaviour. The old skool Honeywell Round is performing well and able to keep a very constant temperature at my place, Evohome is performing very bad and slowly creating huge overshoots and then cooling down again.

                  Some people have suggested to put my requested temperature a degree lower in Evohome, to compensate for this Evohome behaviour. This is not a solution. Yes, it will prevent Evohome from heating up the room too much, but it won't prevent Evohome from letting it cool down too far afterwards.

                  If the 1 minute of heat per 10 minute cycles is not enough to increase the temperature of your room, then there's no problem. You won't get these huge overshoots. So you might not recognize this behaviour. But if it IS enough, then you'll notice Evohome requesting heat from your boiler EVERY 10 minutes, even when the temperature in the zone is already way above the requested temperature. This will go on untill it reaches 0.7 or 1.5 above the requested temperature.

                  I've factory re-set and correctly re-binded countless times already. It makes no difference.

                  I've been in contact with Honeywell and they're going to try and reproduce the behaviour. I hope they will be able to reproduce and create a fix for it... We will wait and see.
                  Hi Erik

                  How is your system installed please? Boiler, number of radiators etc
                  OpenTherm boiler or on/off?

                  Originally posted by Wallyİ View Post
                  Welcome to TPI Erik...

                  It's built into the firmware and here to stay...

                  If Honeywell would just give users the option to enable/disable it...

                  But from what I gather from the experts here...and from reading between the lines...

                  This very expensive 'smart' device will not be eligible for a firmware upgrade...
                  Here's an FAQ on TPI

                  Last edited by top brake; 21 February 2015, 09:34 PM.
                  I work for Resideo, posts are personal and my own views.

                  Comment

                  • Wallyİ
                    Automated Home Sr Member
                    • Jan 2015
                    • 53

                    #39
                    Originally posted by top brake View Post
                    Look...I'm no expert but I do know that TPI is the root cause of this temp overshoot and unwanted boiler demand...

                    I can understand that it adds to the comfort...but I for one would very much like to set my own comfort zone...not Honeywell...

                    My medieval Honeywell wireless CM 927 thermostat with on/off relay does not display any of these issues...not a single one !!!

                    Comment

                    • top brake
                      Automated Home Legend
                      • Feb 2015
                      • 837

                      #40
                      Originally posted by Wallyİ View Post
                      Look...I'm no expert but I do know that TPI is the root cause of this temp overshoot and unwanted boiler demand...

                      I can understand that it adds to the comfort...but I for one would very much like to set my own comfort zone...not Honeywell...

                      My medieval Honeywell wireless CM 927 thermostat with on/off relay does not display any of these issues...not a single one !!!
                      CM927 is a TPI controller
                      I work for Resideo, posts are personal and my own views.

                      Comment

                      • erik
                        Automated Home Guru
                        • Feb 2015
                        • 244

                        #41
                        @Wally: I don't think TPI is the problem. The old Honeywell Round does TPI as well, I think, but works fine. The problem is a bug in the implementation in Evohome is my guess. It never skips a TPI cycle. But it should. But it doesn't. If there's a bug that big in the system, they will HAVE to make new firmware available. The product is too expensivee not to. This would mean they would need to give everyone their money back for a non-functioning system.

                        @Top brake: Boiler is a Valliant VRH 24-28C, heating controlled by BDR91 (On/Off). As described, I've used it both in thermostat modus (only Evotouch and BDR91) and in zone modus (Evotouch, BDR91 and 2 HR92's on 2 radiators in my living room). Using a new Honeywell Round Connected as temp sensor for both situations. I've also tried the HR92's as temp sensor and also tried the Evotouch as temp sensor. The behavior is exactly the same in all cases. Oh, I've also tried HR80's instead of HR92's. Behavior the same.

                        PS: it's better not to quote my entire post. It causes people to have to scroll a lot and doesn't add anything to the discussion
                        Last edited by erik; 21 February 2015, 10:02 PM.

                        Comment

                        • Wallyİ
                          Automated Home Sr Member
                          • Jan 2015
                          • 53

                          #42
                          Originally posted by top brake View Post
                          CM927 is a TPI controller
                          Well...it's set without optimization and tweaked to an absolute minimum boiler demand when unnecessary...

                          The system stay well within its set parameters so the random...though be it regular for the evohome set-up...firing of

                          the boiler/circulation pump does not happen...ever...

                          Comment

                          • top brake
                            Automated Home Legend
                            • Feb 2015
                            • 837

                            #43
                            Originally posted by erik View Post
                            @Wally: I don't think TPI is the problem. The old Honeywell Round does TPI as well, I think, but works fine. The problem is a bug in the implementation in Evohome is my guess. It never skips a TPI cycle. But it should. But it doesn't. If there's a bug that big in the system, they will HAVE to make new firmware available. The product is too expensivee not to. This would mean they would need to give everyone their money back for a non-functioning system.

                            @Top brake: Boiler is a Valliant VRH 24-28C, heating controlled by BDR91 (On/Off). As described, I've used it both in thermostat modus (only Evotouch and BDR91) and in zone modus (Evotouch, BDR91 and 2 HR92's on 2 radiators in my living room). Using a new Honeywell Round Connected as temp sensor for both situations. I've also tried the HR92's as temp sensor and also tried the Evotouch as temp sensor. The behavior is exactly the same in all cases. Oh, I've also tried HR80's instead of HR92's. Behavior the same.

                            PS: it's better not to quote my entire post. It causes people to have to scroll a lot and doesn't add anything to the discussion
                            I have a very similar setup at home with a Vaillant boiler and radiator zones using Y87 thermostats as sensors. Everything stable at set temperature, have also used a variety of HR80 and HR92. Optimum start and stop enabled.

                            What cycle rate and minimum run time do you have set?
                            Any other changes made to system or zone parameters?

                            I would also suggest that you check that the radiator valves are actually fully closed (can shut off totally)

                            P.s. How are you measuring the temperature to less than half degree increments?
                            Last edited by top brake; 21 February 2015, 10:41 PM.
                            I work for Resideo, posts are personal and my own views.

                            Comment

                            • erik
                              Automated Home Guru
                              • Feb 2015
                              • 244

                              #44
                              the reason you're not seeing it might be that your setup doesn't raise the room temperature when requesting heat only 1 minute per 10minutes. If it doesn't, it won't affect you. Maybe you could try putting al zones to 5 degrees, and putting just 1 well isolated zone with big enough radiator(s) on 16 degrees (make sure it's below 16 before you start), putting minimum run time on 3 minutes. And then see if it goes over 16 or not. I certainly would expect it to. Most systems should be able to raise temperature to over 16 degrees when going ON 3 minutes per 10 minutes.

                              My cycle rate: 6x per hour, minimum run time: tried 1 minute, 2 minutes and 3 minutes. All same result.

                              other changes right now: disabled local control, changed max temp to 25. Nothing that would matter. Also, I've tried with factory reset settings, didn't touch anything. Didn't make a difference.

                              measurements: with my own thermometers. Also confirmed by getting read-outs of my system directly from Honeywell (Evohome actually measures much more precise numbers than it displays on the screen)
                              Last edited by erik; 21 February 2015, 11:51 PM.

                              Comment

                              • top brake
                                Automated Home Legend
                                • Feb 2015
                                • 837

                                #45
                                Originally posted by erik View Post
                                the reason you're not seeing it might be that your setup doesn't raise the room temperature when requesting heat only 1 minute per 10minutes. If it doesn't, it won't affect you.

                                cycle rate: 6x per hour, minimum run time: tried 1 minute, 2 minutes and 3 minutes. All same result.

                                other changes right now: disabled local control, changed max temp to 25. Nothing that would matter. Also, I've tried with factory reset settings, didn't touch anything. Didn't make a difference.

                                measurements: with my own thermometers. Also confirmed by getting read-outs of my system directly from Honeywell (Evohome actually measures much more precise numbers than it displays on the screen)
                                Thanks for sharing
                                Interested to hear what feedback you get from support
                                I work for Resideo, posts are personal and my own views.

                                Comment

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