Hometronic HC60NG Cycling : Solution

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  • drawdog
    Automated Home Jr Member
    • Dec 2008
    • 19

    Hometronic HC60NG Cycling : Solution

    The HC60NG has been cycling my boiler for some time now and slowly driving me crazy, so why I didn't think of this solution before now is a mistery !

    I've added a 'time delay' relay into the boiler control circuit. The relay coil is energised by the HC60NG when calling for heating, the relay contacts supply the boiler with 240v. The relay allows a variable time delay to be set between the coil energising and the contacts closing. I've used 10min as a delay time.

    If the HC60NG is simply cycling (as it tends to do, a lot) then the relay will receive the 240v feed, but the boiler will only start if the 240v feed exists for more than 10mins (in my case). As a result the relay filters out the cycling request and only starts the boiler when the controls are making a more serious request for heat.

    Boiler cycling has now completely stopped, the only very minor downside is that I have to wait 10mins before the boiler will start after a genuine request but this has actually not been noticed.

    Hope this helps somebody out there...
  • JohnnyP
    Automated Home Jr Member
    • Nov 2008
    • 38

    #2
    That's very interesting. I'm not a big sufferer, but may still give your solution a try - it certainly sounds ideal. What's the name of the relay, and where can I buy one? Thanks for sharing your innovation.

    Comment

    • toscal
      Moderator
      • Oct 2005
      • 2061

      #3
      Quite often boiler cycling can be caused by the rad water temp not set high enough (this is normally adjusted at the boiler), or the setback temp is too close to the normal temp.
      While you have solved the problem you may not have fixed the condition that causes it. But good idea anyway.
      IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
      Renovation Spain Blog

      Comment

      • drawdog
        Automated Home Jr Member
        • Dec 2008
        • 19

        #4
        I've done extensive testing with my Hometronic system, the HC60NG causes the cycling problem and the boiler is the victim. No matter what you do with set-back, temperatures, etc the system eventually returns to cycling as rooms reach the set-point. The only sure way to avoid the problem is to set-back to a temperature way below a point that you could ever reach in each zone, this (in my mind) defeats the potential advantages of using Hometronic in the first place.

        The 'condition that causes the problem' is the firmware within the HC60NG which cannot be modified, this method seems to be one way of saving the boiler from this constant bullying

        Comment

        • drawdog
          Automated Home Jr Member
          • Dec 2008
          • 19

          #5
          Delay Relay

          I've used the following relay parts from RS Comp :

          Relay = RS 256-5262
          Socket = RS 329-9871
          Timer = RS 329-9922
          Clip = RS 231-2131

          You can adjust the relay operation and delay, etc

          Comment

          • JohnnyP
            Automated Home Jr Member
            • Nov 2008
            • 38

            #6
            Thanks for the list of components. Do you think that the Broyce Control M1EDK (RS 300-6174) would also fit the bill?

            BTW - you're right that cycling is inevitable with the HC60NG.

            Comment

            • drawdog
              Automated Home Jr Member
              • Dec 2008
              • 19

              #7
              Relay type ?

              Don't see a problem, and it looks simpler than my set-up ! Needs a DIN rail to mount correctly but thats no big deal. Let me know how you get on...

              Comment

              • toscal
                Moderator
                • Oct 2005
                • 2061

                #8
                Originally posted by drawdog View Post
                I've done extensive testing with my Hometronic system, the HC60NG causes the cycling problem and the boiler is the victim. No matter what you do with set-back, temperatures, etc the system eventually returns to cycling as rooms reach the set-point. The only sure way to avoid the problem is to set-back to a temperature way below a point that you could ever reach in each zone, this (in my mind) defeats the potential advantages of using Hometronic in the first place.

                The 'condition that causes the problem' is the firmware within the HC60NG which cannot be modified, this method seems to be one way of saving the boiler from this constant bullying
                Fair enough, I wonder if the house heat system has similar problems. And I guess Honeywell aren't that bothered in updating the firmware. Or if they do it will probably cost.
                Did you have a look at the DIYnot forums.
                http://www.diynot.com/forums/viewtopic.php?t=157962 don't know if this is of any help to you.
                IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                Renovation Spain Blog

                Comment

                • drawdog
                  Automated Home Jr Member
                  • Dec 2008
                  • 19

                  #9
                  Hometronic Operation

                  In the defense of Honeywell perhaps it depends on the design philosophy behind the firmware. If the aim was to offer accurate temperature control in each zone, and quick reaction to heating demand, then maintaining the circulating water at close to required temperature would make sense. A regular boiler cycle would ensure hot water was always available even if actual demand was minimal. The system could then react quickly to a valve request. I'm of the opinion that the running cost and system wear & tear are increased as a result...given the option I'd prefer to have the boiler stay off overnight - thus the relay

                  The cycling is part of the HC60NG firmware, the genuine reason for it's inclusion would be great to understand but as with a lot of the Hometronic options I can't find any details.

                  I'm happy with the Hometronic as a package, and more so now the HC60NG has been put on a leash !

                  Comment

                  • JohnnyP
                    Automated Home Jr Member
                    • Nov 2008
                    • 38

                    #10
                    9 months later and I've finally fitted the time delay relay! It's working beautifully, intercepting all the unwanted cycling requests. I have set the time delay at 3mins 15secs for now. If anyone would like to know the wiring of the Broyce Control M1EDK I'd be happy to pm. Thanks again to drawdog for the idea and advice.

                    Comment

                    • JohnnyP
                      Automated Home Jr Member
                      • Nov 2008
                      • 38

                      #11
                      I've had a few requests for the wiring of the M1EDK time delay relay, and since I can't work out how to send an attachment in a pm, I've attached it here.

                      I strongly recommend using the test circuit with a lightbulb first - it's safer, and also easier to set the time delay.

                      Usual disclaimers of course - use at your own risk.
                      Attached Files

                      Comment

                      • drawdog
                        Automated Home Jr Member
                        • Dec 2008
                        • 19

                        #12
                        A solution

                        I'm pleased this solution is spreading, thanks to JohnnyP for the wiring details - if anybody has alternative solutions let us know. I've now increased the timer delay, the theory being that if the boiler is cycling due to low demand then it may as well wait a little longer and have more work to do (ie longer run time)

                        Comment

                        • prmedloc
                          Automated Home Lurker
                          • Sep 2009
                          • 2

                          #13
                          I've got my M1EDK in and working with the comzone stuff now as well. Seems to be working fine.

                          Comment

                          • rakesprogress
                            Automated Home Lurker
                            • Sep 2008
                            • 2

                            #14
                            Another solution

                            Hi everyone,

                            With 24 HR80s, 4 CM67zs and just one hc60ng connected, I started getting the cycling problem (with no red lights), and this is the beginning of my second winter with it. I reset a few times, re-linked the HR80s and the CM67zs. None of this made any difference.

                            But then I took the latest hc60ng and replaced the original one on the wall. The wiring stays the same. You just clip on the front part with the brain.

                            It works. So far. And I have 2 more in case it happens again. The board is noiceably different.

                            Comment

                            • rakesprogress
                              Automated Home Lurker
                              • Sep 2008
                              • 2

                              #15
                              Er, almost back to square one. At least I have ruled out a faulty HC60NG...

                              Comment

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