Hot Water issue - Random Overshoots

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  • The EVOHOME Shop
    Site Sponsor
    • Dec 2014
    • 483

    #31
    Originally posted by Edinburgh2000 View Post
    Please do not close your file on the CS92 overshoots just yet.
    Any chance of seeing some images of your installation, including a plan of your property?

    Apart from selling the evohome items we are not directly connected to Honeywell. Not that I don't take all feedback we are given seriously, as Simon would tell you we do bend over backwards for our customers.

    However, it must be stated that cylinders have been doing this for years without anyone knowing about it. Do you think mechanical rod and liquid expansion thermostats in dry pockets are reliably accurate?

    At the end of the day 60 degrees C is still too hot to be useful, so does it really matter if this goes to 62.5 degrees C instead of 60? If all Legionella bacterial is eliminated, isn't this the primary aim?

    We have a system being launched today that gives you really high hot water flow rates from a combi boiler and this will be the way forwards for a lot of people. If you are genuinely interested in saving money on hot water bills and preventing fuel wastage, this system would be for you.

    Comment

    • Dan_Robinson
      Automated Home Ninja
      • Jun 2012
      • 347

      #32
      Don't forget stratification 9n larger cylinders.
      Kind Regards - Dan Robinson (Jennings Heating Ltd)

      Comment

      • Edinburgh2000
        Automated Home Guru
        • Dec 2016
        • 134

        #33
        Originally posted by The EVOHOME Shop View Post
        Any chance of seeing some images of your installation, including a plan of your property?
        I am told by those who know about such things that certain gentlemen's magazines have sections called "Readers' Wives" . At the risk of dragging this forum down to such depths.......................here are some pictures of my boiler room.


        [Megaflo cylinder.jpg


        Boiler room.jpg


        Heating controls.jpg


        The four BDR91s work fine. The CS92 is at the bottom left of the array. The temperature probe is on the thin black wire entering the Megaflo cylinder in its purpose-built pocket.

        The house is a large three-storey Victorian property. The rooms are high (~3.5m) with the traditional Scottish clinker-fill of the ceiling spaces for sound and thermal insulation. The boiler room is on the top (2nd) floor. I normally keep the Evotouch controller docked in the kitchen on the ground floor.
        Last edited by Edinburgh2000; 1 September 2017, 01:34 PM. Reason: Punctuation corrected

        Comment

        • DBMandrake
          Automated Home Legend
          • Sep 2014
          • 2361

          #34
          Very nice and tidy looking but..... that CS92 is way too close to the BDR91's in my opinion. It needs to be moved somewhere else. I put mine on a different wall to the BDR91's which also angled it at 90 degrees orientation. The box to the right of the CS92 - is that a metal box or plastic ?

          Also I notice a controller wall mount currently unoccupied - do you actually have the controller sitting in the wall mount there in such close proximity when you are having problems or do you have another mount somewhere else in the house where it usually sits ? Edit: never mind, I re-read your post. Seems an odd place to install the wall mount though.
          Last edited by DBMandrake; 1 September 2017, 12:31 PM.

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          • Edinburgh2000
            Automated Home Guru
            • Dec 2016
            • 134

            #35
            Originally posted by The EVOHOME Shop View Post
            At the end of the day 60 degrees C is still too hot to be useful
            So how do you clean your greasy pots and pans? When I have my Marigold gloves on for the washing up I need some very hot water. I set mine to 58o (+0 / -8) and that is only just hot enough to clean greasy pots.

            Comment

            • DBMandrake
              Automated Home Legend
              • Sep 2014
              • 2361

              #36
              He probably means 60 degrees at the tap is too hot - which it is, you're getting close to scalding temperatures. But if you have a long pipe run the temperature at the tap is probably several degrees lower. Have you put a thermocouple temperature probe into the flow from the tap to measure it ? I have quite a short run from my hot water cylinder which is right next to the kitchen on the other side of the kitchen wall (although the pipe runs up into the ceiling, across, down and doubles back a bit) and I still see a loss of about 2-3 degrees in that short run, partly because it's a vented cylinder with lower pressure/flow output.

              Comment

              • Edinburgh2000
                Automated Home Guru
                • Dec 2016
                • 134

                #37
                Originally posted by DBMandrake View Post
                that CS92..........needs to be moved somewhere else. I put mine on a different wall to the BDR91's which also angled it at 90 degrees orientation.
                My installer originally put the CS92 on the wall beside the cylinder (i.e. angled at 90 degrees) but that did not work well - I guess because it was too close to the cylinder. By trial and error I found the back wall (where it is now) to work best. At present it is working fine and is, as you note, just below the DHW BDR91.


                Originally posted by DBMandrake View Post
                The box to the right of the CS92 - is that a metal box or plastic ?

                Also I notice a controller wall mount currently unoccupied - do you actually have the controller sitting in the wall mount there in such close proximity when you are having problems or do you have another mount somewhere else in the house where it usually sits ? Edit: never mind, I re-read your post. Seems an odd place to install the wall mount though.
                I have that wall mount for when I am messing about with the system. It lets me programme the controller while watching what is going on with the BDR91s and my motorised valves, without worrying about the battery in the controller dying. Given that there is no indication on the controller of the call for heat, I find it better to do this analysis in the boiler room where I can see what is happening. And the box is plastic and is just a home-made mounting for lights to show me the position of the valves.
                Last edited by Edinburgh2000; 1 September 2017, 03:41 PM.

                Comment

                • mtmcgavock
                  Automated Home Legend
                  • Mar 2017
                  • 507

                  #38
                  To revive an old thread, my own system overshot tonight whether this was a one off issue or it will continue to do so i'm not sure. But it reached the magic number of 62oc, and switched off at this. As it's roughly 12 months old now suspecting it's just the batteries, so replaced them and will monitor to see if it reoccurs.

                  Comment

                  • HenGus
                    Automated Home Legend
                    • May 2014
                    • 1001

                    #39
                    Originally posted by mtmcgavock View Post
                    To revive an old thread, my own system overshot tonight whether this was a one off issue or it will continue to do so i'm not sure. But it reached the magic number of 62oc, and switched off at this. As it's roughly 12 months old now suspecting it's just the batteries, so replaced them and will monitor to see if it reoccurs.
                    And the target temperature is...?

                    Comment

                    • mtmcgavock
                      Automated Home Legend
                      • Mar 2017
                      • 507

                      #40
                      Originally posted by HenGus View Post
                      And the target temperature is...?
                      55oc with a 3 minute over run, which usually takes it to around 57oc (Never any more), there's then a 9oc differential. I've reduced this down to 50oc as my other half is complain her hot water is too hot...it'll show more if it overshoots too.

                      Comment

                      • HenGus
                        Automated Home Legend
                        • May 2014
                        • 1001

                        #41
                        I have never seen a 7C overshoot in 4 years and 2 boilers. I managed 1C overshoot yesterday.

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                        • fergie
                          Automated Home Sr Member
                          • Mar 2017
                          • 92

                          #42
                          Originally posted by mtmcgavock View Post
                          55oc with a 3 minute over run.
                          Shouldn't hot water be stored at least 60?

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