EvoHome Hot water temperature incorrect

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • Jemster
    Automated Home Guru
    • Dec 2018
    • 123

    #16
    Originally posted by mtmcgavock View Post
    If I remember correctly, to replace the Stat on these you remove the 3 little screws in the top plastic cover. This will expose the stats and the pockets. You'll be able to then push it into there, not disturbing the other stats. Remember to isolate all the power to the system first!
    Oh? Are those not the stats in the round section below the plastic cover visible in the photo (beside the stuffed in insertion sensor)?
    Haven’t managed to get to it today as the heat is on so will give it a stab on Saturday to see if I can improve the situation.

    Comment

    • mtmcgavock
      Automated Home Legend
      • Mar 2017
      • 507

      #17
      Originally posted by Jemster View Post
      Oh? Are those not the stats in the round section below the plastic cover visible in the photo (beside the stuffed in insertion sensor)?
      Haven’t managed to get to it today as the heat is on so will give it a stab on Saturday to see if I can improve the situation.
      No, the round thing with the black wires coming out is the immersion heater. The temperature probes aren't visible, they are behind the plastic cover above if I remember correctly.

      Comment

      • fezster
        Automated Home Sr Member
        • Dec 2017
        • 72

        #18
        That's incorrect. There are 2 dry pockets above and below the connections for the immersion heater.

        I'm basing this on my own cylinder, but this looks identical. A close up picture would help clarify. You should see wires going into the dry pockets - 2 in each if they both have overheat stats as well as regular stats.

        The top plastic cover is for the boost immersion. The temperature up there will be far higher than lower in the cylinder due to stratification. You need to ensure the cs92 is inserted as low as possible in the cylinder to have it function correctly.

        Comment

        • mtmcgavock
          Automated Home Legend
          • Mar 2017
          • 507

          #19
          Originally posted by fezster View Post
          That's incorrect. There are 2 dry pockets above and below the connections for the immersion heater.

          I'm basing this on my own cylinder, but this looks identical. A close up picture would help clarify. You should see wires going into the dry pockets - 2 in each if they both have overheat stats as well as regular stats.

          The top plastic cover is for the boost immersion. The temperature up there will be far higher than lower in the cylinder due to stratification. You need to ensure the cs92 is inserted as low as possible in the cylinder to have it function correctly.
          I think you’re misunderstanding what I meant by top plastic cover. I’m meaning the plastic fascia with 3 screws in within the bottom compartment. This holds the immersion and boiler stats in place are and where the relevant probes/pockets will be for each stat.

          Comment

          • Jemster
            Automated Home Guru
            • Dec 2018
            • 123

            #20
            Ok, I gotta say I thought the same as Fezster.

            If we call the plastic fascia 'North', the round circle has 4 'features', East and West are terminals with wires - I assume these are the immersion heater circuit. North and South appear to be holes with what looks like something black pushed into each with 2 wires coming from each - I thought these were the stats.

            I haven't taken off the top plastic fascia, it seems to cover the immersion and boiler stat settings and reset buttons. I'm not denying there's further pockets under that section mtmcgavock, I simply haven't looked yet.

            The photo was a hi-res closeup, I didn't realise the board scaled it down and rotated it 90 degrees! (at least, I can only assume that's how it got to postage stamp sized!)
            Last edited by Jemster; 11 January 2019, 09:31 AM. Reason: Dyscompasslexia

            Comment

            • paulockenden
              Automated Home Legend
              • Apr 2015
              • 1719

              #21
              The pockets (why do we call them pockets? They are tubes) for the sensors are under the incredibly flimsy grey plastic cover, and the stats.

              Comment

              • fezster
                Automated Home Sr Member
                • Dec 2017
                • 72

                #22
                Originally posted by Jemster View Post
                Ok, I gotta say I thought the same as Fezster.

                If we call the plastic fascia 'North', the round circle has 4 'features', East and West are terminals with wires - I assume these are the immersion heater circuit. North and South appear to be holes with what looks like something black pushed into each with 2 wires coming from each - I thought these were the stats.

                I haven't taken off the top plastic fascia, it seems to cover the immersion and boiler stat settings and reset buttons. I'm not denying there's further pockets under that section mtmcgavock, I simply haven't looked yet.

                The photo was a hi-res closeup, I didn't realise the board scaled it down and rotated it 90 degrees! (at least, I can only assume that's how it got to postage stamp sized!)
                That's it - "North" and "South", as per your description, contain the stats. The 2 wires in each correspond to the overheat stat (which will be spring like and inserted furthest into the pocket) and the immersion/cylinder stat (which will be a 3 to 4 inch long NTC). Take your pick on which pocket you want to use, but you can definitely squeeze one more stat in there, albeit it is quite tight.

                Comment

                • fezster
                  Automated Home Sr Member
                  • Dec 2017
                  • 72

                  #23
                  Originally posted by mtmcgavock View Post
                  I think you’re misunderstanding what I meant by top plastic cover. I’m meaning the plastic fascia with 3 screws in within the bottom compartment. This holds the immersion and boiler stats in place are and where the relevant probes/pockets will be for each stat.
                  Ok, I'm not sure I have this plastic cover. If I remove the lower grey cover on the cylinder, this is what I see - you can see the 2 dry pockets and the wires leading into them with the stats.

                  megaflo stats.jpg

                  Comment

                  • Jemster
                    Automated Home Guru
                    • Dec 2018
                    • 123

                    #24
                    Fezster, that’s about the same as mine. Today I got the sensor tucked up against the cylinder wall with some polystyrene holding it tight. The readings have gone up by 6-7 degrees, close, but not quite there yet. Going to order up some thermal paste - I thought I had some but it seems to have disappeared. No doubt it’ll show up as soon as the new one arrives
                    If there’s still a little discrepancy I’ll compensate by adjusting the evohome target temperature a few degrees.

                    Comment

                    • Jemster
                      Automated Home Guru
                      • Dec 2018
                      • 123

                      #25
                      Just for the sake of thread completeness ... as mentioned previously, thermal paste is the key. I took out the sensor, smeared it liberally on the contacting side with some very conductive thermal paste and tucked it back into the same spot. The temperature readings are now matching between the sensor, and the tank water outlet pipe after I've run a hot tap for a minute.

                      Thanks for all the help, that's one more gremlin out of the system.

                      Hasn't made any difference with the gas consumption, but at least I now know it's not caused by the hot water cylinder.

                      Comment

                      Working...
                      X