Evohome Hot Water Safety

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  • top brake
    Automated Home Legend
    • Feb 2015
    • 837

    #16
    Originally posted by thepook View Post
    Have already read and understood G3, and my system complies completely for a replacement of existing.

    My controller does not offer the fail safe settings option - it seems that these only appear if you have a boiler demand relay configured. My question to Honeywell was what fail safe behaviour applies when you only have 2 BDR91s acting as heating and dhw zone valves.

    I agree entirely about the max possible temps, but my boiler can output 86 deg, so I have set the Evohome to 60 deg and have the secondary stat set just over 65, so it normally does nothing, but in a fault limits the dhw temp - seems a lot safer than depending on wireless to me, plus its no real trouble on an existing system with a stat. It should really be the recommended standard installation for wireless systems imho.

    I also understand and agree about the TMV comment.
    image.jpg

    My evohome system at home is application type 4 in the appendix with a boiler relay and single hot water valve
    This retains the ability to set the parameters of cycle rate and minimum run time, a fail safe on the heating if the comms are lost (see pic above), it also allows you to set the hot water temperature, differential and overun

    On your 'sundial' system the operation is that evo opens the relay according to the demand and if the comms are lost on the hot water sensor the hot water relay will not switch on. There is no fail safe setting to run the hot water on a purely timed basis for obvious reasons.
    Last edited by top brake; 8 February 2015, 01:34 AM.
    I work for Resideo, posts are personal and my own views.

    Comment

    • sharpener
      Automated Home Sr Member
      • Jan 2015
      • 78

      #17
      Originally posted by thepook View Post
      My controller does not offer the fail safe settings option - it seems that these only appear if you have a boiler demand relay configured. My question to Honeywell was what fail safe behaviour applies when you only have 2 BDR91s acting as heating and dhw zone valves.

      I agree entirely about the max possible temps, but my boiler can output 86 deg, so I have set the Evohome to 60 deg and have the secondary stat set just over 65, so it normally does nothing, but in a fault limits the dhw temp - seems a lot safer than depending on wireless to me, plus its no real trouble on an existing system with a stat. It should really be the recommended standard installation for wireless systems imho.
      The feature Honeywell describes as "fail safe" is that (if fail safe is enabled) the boiler relay just defaults to a fixed duty cycle (from memory, on 25% of the time) in the absence of the wireless link. This is hardly "fail safe" in the accepted use of the phrase, except insofar as it provides a measure of frost protection.

      I agree with thepook that the behaviour of all aspects of the system when the wireless links are down should be better defined and properly documented for the user. Like him I am also glad that I have kept the original hard-wired HW controls, particularly as I have an unvented tank, and also that I have an entirely separate remote control facility using an Aviosys IP9212 control box whereby I can turn the heating on while I am away if frost is expected. Defence in depth!

      Comment

      • G4RHL
        Automated Home Legend
        • Jan 2015
        • 1580

        #18
        Originally posted by thepook View Post
        Yes, think I understand the sentiment of the post Re: safety, but I would hope that you understand my view of safety, given that I am asking questions about the fail safe behaviour of the system that are not answered by the manuals, the manufacturer's own online training, or as yet their own customer services department. I have also added a secondary thermostat to my system that is hard wired for safety, even though not specifically required for vented systems.

        I would also add that my experiences so far in life tell me that there is a vast gulf between being trained and being truly competent.
        Is it the case that those who are trained write the procedures and produce all the admin performance stuff and those who are competent do the work?! The "competent" by the very nature of the word are trained, some simply by experience.

        Comment

        • top brake
          Automated Home Legend
          • Feb 2015
          • 837

          #19
          Originally posted by G4RHL View Post
          Is it the case that those who are trained write the procedures and produce all the admin performance stuff and those who are competent do the work?! The "competent" by the very nature of the word are trained, some simply by experience.
          You need both education and experience

          Unconscious incompetence
          The individual does not understand or know how to do something and does not necessarily recognize the deficit. They may deny the usefulness of the skill. The individual must recognize their own incompetence, and the value of the new skill, before moving on to the next stage.[2] The length of time an individual spends in this stage depends on the strength of the stimulus to learn.[3]

          Conscious incompetence
          Though the individual does not understand or know how to do something, he or she does recognize the deficit, as well as the value of a new skill in addressing the deficit. The making of mistakes can be integral to the learning process at this stage.[4]

          Conscious competence
          The individual understands or knows how to do something. However, demonstrating the skill or knowledge requires concentration. It may be broken down into steps, and there is heavy conscious involvement in executing the new skill.[3]

          Unconscious competence
          The individual has had so much practice with a skill that it has become "second nature" and can be performed easily. As a result, the skill can be performed while executing another task. The individual may be able to teach it to others, depending upon how and when it was learned.

          Last edited by top brake; 8 February 2015, 10:02 AM.
          I work for Resideo, posts are personal and my own views.

          Comment

          • The EVOHOME Shop
            Site Sponsor
            • Dec 2014
            • 483

            #20
            Originally posted by top brake View Post
            You need both education and experience


            http://en.m.wikipedia.org/wiki/Four_..._of_competence
            Amen to that!!!

            The amount of installers out there with 'relevant training' (i.e. the capabilities to pass a multiple choice, open book examination) is vast... Sadly I find most have 'experience' in short supply and this is where our industry fails.

            Its always really important to discuss relevant experience with your evohome installer and get testimonials of their work where possible. In the case of Honeywell's Installer Network if you have bad feedback about anyone on the list, I know one person in particular at Honeywell who would want to know.

            Comment

            • G4RHL
              Automated Home Legend
              • Jan 2015
              • 1580

              #21
              Originally posted by The EVOHOME Shop View Post
              Amen to that!!!

              The amount of installers out there with 'relevant training' (i.e. the capabilities to pass a multiple choice, open book examination) is vast... Sadly I find most have 'experience' in short supply and this is where our industry fails.

              Its always really important to discuss relevant experience with your evohome installer and get testimonials of their work where possible. In the case of Honeywell's Installer Network if you have bad feedback about anyone on the list, I know one person in particular at Honeywell who would want to know.
              Not just your industry where it fails. It happens a lot in the professions where the training is so focussed on one field that the broader picture is never seen. We have digressed! Probably my fault in part. Anyway my Evohome system is working well. A great system and yes at last I have full control from the app as well although when roaming no matter what network is used (have tried O2, EE and Vodafone) and even strong 4G signals it is hit and miss whether it will log in.

              Whilst on the subject of hot water though for some reason my temperature setting reverted back to 50c from 60c. It may have been because I reset the hot water relay and rebound it even though I did not change the temperature in the parameters.

              Comment

              • thepook
                Automated Home Jr Member
                • Jan 2015
                • 32

                #22
                Originally posted by The EVOHOME Shop View Post

                The amount of installers out there with 'relevant training' (i.e. the capabilities to pass a multiple choice, open book examination) is vast... Sadly I find most have 'experience' in short supply and this is where our industry fails.
                That was exactly my point re: the use of the word 'competent' needing caution.

                Interesting debate, folks!

                Comment

                • thepook
                  Automated Home Jr Member
                  • Jan 2015
                  • 32

                  #23
                  Originally posted by top brake View Post
                  [ATTACH=CONFIG]478[/ATTACH]

                  My evohome system at home is application type 4 in the appendix with a boiler relay and single hot water valve
                  This retains the ability to set the parameters of cycle rate and minimum run time, a fail safe on the heating if the comms are lost (see pic above), it also allows you to set the hot water temperature, differential and overun

                  On your 'sundial' system the operation is that evo opens the relay according to the demand and if the comms are lost on the hot water sensor the hot water relay will not switch on. There is no fail safe setting to run the hot water on a purely timed basis for obvious reasons.
                  Yes, I have considered buying another BDR91 to use as a boiler relay, just to get those functions back, or converting my plumbing to the application you have.

                  Comment

                  • The EVOHOME Shop
                    Site Sponsor
                    • Dec 2014
                    • 483

                    #24
                    Originally posted by thepook View Post
                    That was exactly my point re: the use of the word 'competent' needing caution.

                    Interesting debate, folks!
                    Indeed... Relevant Training AND Experience = Competence!

                    This is going off topic but all my training was not at the expense of customers, as I completed a little thing called an 'apprenticeship'. This is by far the best way of introducing new recruits into the industry, not the platforms we currently use which limit real world experience!

                    Comment

                    • thepook
                      Automated Home Jr Member
                      • Jan 2015
                      • 32

                      #25
                      Originally posted by top brake View Post
                      [ATTACH=CONFIG]478[/ATTACH]

                      My evohome system at home is application type 4 in the appendix with a boiler relay and single hot water valve
                      This retains the ability to set the parameters of cycle rate and minimum run time, a fail safe on the heating if the comms are lost (see pic above), it also allows you to set the hot water temperature, differential and overun

                      On your 'sundial' system the operation is that evo opens the relay according to the demand and if the comms are lost on the hot water sensor the hot water relay will not switch on. There is no fail safe setting to run the hot water on a purely timed basis for obvious reasons.
                      By the way, did you notice that in the diagram you refer to, Honeywell have the code for the 2 port valve wrong - even though its their own code for their own product.

                      Comment

                      • top brake
                        Automated Home Legend
                        • Feb 2015
                        • 837

                        #26
                        Originally posted by thepook View Post
                        By the way, did you notice that in the diagram you refer to, Honeywell have the code for the 2 port valve wrong - even though its their own code for their own product.
                        Yes it's a typo well spotted!
                        I work for Resideo, posts are personal and my own views.

                        Comment

                        • The EVOHOME Shop
                          Site Sponsor
                          • Dec 2014
                          • 483

                          #27
                          Originally posted by thepook View Post
                          By the way, did you notice that in the diagram you refer to, Honeywell have the code for the 2 port valve wrong - even though its their own code for their own product.
                          They know lol...

                          Comment

                          • thepook
                            Automated Home Jr Member
                            • Jan 2015
                            • 32

                            #28
                            Originally posted by top brake View Post
                            [ATTACH=CONFIG]478[/ATTACH]

                            My evohome system at home is application type 4 in the appendix with a boiler relay and single hot water valve
                            This retains the ability to set the parameters of cycle rate and minimum run time, a fail safe on the heating if the comms are lost (see pic above), it also allows you to set the hot water temperature, differential and overun

                            On your 'sundial' system the operation is that evo opens the relay according to the demand and if the comms are lost on the hot water sensor the hot water relay will not switch on. There is no fail safe setting to run the hot water on a purely timed basis for obvious reasons.

                            That's something else I would like to understand about the behaviour of the Evohome in my type of installation - Since I cannot configure the Cycle Rate and Minimum On Time options, what are the limits to those by default? In other words, how frequently and for what minimum time could my heating zone BDR91 operate, and effectively call the boiler for heat via the mid-position valve?

                            Thanks in advance for your help.
                            Last edited by thepook; 9 February 2015, 11:29 PM.

                            Comment

                            • thepook
                              Automated Home Jr Member
                              • Jan 2015
                              • 32

                              #29
                              Originally posted by top brake View Post
                              Yes it's a typo well spotted!
                              In looking further into changing my plumbing to an S-plan minus type, like Figure 4 in the manual, is Figure 4 not missing another BDR91 acting as a Boiler Relay?

                              Otherwise, how can it fire the boiler for heating only without opening the DHW Zone Valve?

                              Comment

                              • top brake
                                Automated Home Legend
                                • Feb 2015
                                • 837

                                #30
                                Originally posted by thepook View Post
                                In looking further into changing my plumbing to an S-plan minus type, like Figure 4 in the manual, is Figure 4 not missing another BDR91 acting as a Boiler Relay?

                                Otherwise, how can it fire the boiler for heating only without opening the DHW Zone Valve?
                                indeed it is

                                here is an updated diagram, the instructions are currently being re-issued

                                fig 4 updated.jpg
                                I work for Resideo, posts are personal and my own views.

                                Comment

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