Evohome hot water problems

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  • Mark Had
    Automated Home Lurker
    • Nov 2021
    • 6

    Evohome hot water problems

    We have Honeywell evohome and I need a bit of help re the hot water. It’s been getting seriously overheated, up to 80deg in our Megaflo. I have it set to 65 with 10 differential. It seems to have started since the radiators are now coming on. I replaced the battery in the hw sensor. What was odd was that they were flat yet I was still getting a temp reading?
    Anyway, had some fun and games re binding the hot water sensor and relay but think it’s now connected. However the water is still over heating. I turned off the hw for a few days but it’s still getting very hot. I am guessing either the valve is stuck open or it’s not setup correctly or I messed it up when rebinding it? Is there a way to force the valve to open/close to see if it’s working? If it’s not that is there anything else it could be? We’ve had it a couple for of years. May well have had the problem last year but as we always had hot water I never really noticed.
    Thanks in advance.
  • mtmcgavock
    Automated Home Legend
    • Mar 2017
    • 507

    #2
    Originally posted by Mark Had View Post
    We have Honeywell evohome and I need a bit of help re the hot water. It’s been getting seriously overheated, up to 80deg in our Megaflo. I have it set to 65 with 10 differential. It seems to have started since the radiators are now coming on. I replaced the battery in the hw sensor. What was odd was that they were flat yet I was still getting a temp reading?
    Anyway, had some fun and games re binding the hot water sensor and relay but think it’s now connected. However the water is still over heating. I turned off the hw for a few days but it’s still getting very hot. I am guessing either the valve is stuck open or it’s not setup correctly or I messed it up when rebinding it? Is there a way to force the valve to open/close to see if it’s working? If it’s not that is there anything else it could be? We’ve had it a couple for of years. May well have had the problem last year but as we always had hot water I never really noticed.
    Thanks in advance.
    Sounds like it's wired up wrong, especially as that the High Limit stat on the cylinder should be still wired in series with the zone valve. When the heatings calling it sounds as if it's heating the cylinder too.

    Comment

    • Mark Had
      Automated Home Lurker
      • Nov 2021
      • 6

      #3
      Thank you. Yes it’s definitely being heated whenever the boiler is on. Why do you think it’s the wiring and not the valve being stuck on?

      Comment

      • mtmcgavock
        Automated Home Legend
        • Mar 2017
        • 507

        #4
        Originally posted by Mark Had View Post
        Thank you. Yes it’s definitely being heated whenever the boiler is on. Why do you think it’s the wiring and not the valve being stuck on?
        You'd need to test if there's power to the valve, and check whether it's been locked open. Is it a Honeywell Valve?

        Comment

        • Mark Had
          Automated Home Lurker
          • Nov 2021
          • 6

          #5
          I’m not sure the make. Is there a way to
          Make it open and close? Button on the relay or through the evohome controller?

          Comment

          • mtmcgavock
            Automated Home Legend
            • Mar 2017
            • 507

            #6
            Originally posted by Mark Had View Post
            I’m not sure the make. Is there a way to
            Make it open and close? Button on the relay or through the evohome controller?
            Yes they have a manual override. Some valves will stay perm open if you operate the lever. That maybe your issue, but hard to say if you don't know the make of valve. Maybe a picture might help?

            Comment

            • Mark Had
              Automated Home Lurker
              • Nov 2021
              • 6

              #7
              Ok had a good look and photos to follow. I have 2 Honeywell valves. Bother have power going to them (my little power pen beeps when touching the cable). The little slider on the one to the left (which goes to the tank) moves with no resistance. The one on the right which bends back and is before the other valve moves to a half way point only. I think I heard this one randomly move but not by me. If I switch the relay off or on by pressing the green button nothing happens. If it switch the hw off or on via the controller nothing happens.
              Last edited by Mark Had; 7 November 2021, 12:39 PM.

              Comment

              • mtmcgavock
                Automated Home Legend
                • Mar 2017
                • 507

                #9
                Faulty wiring or stuck valve.

                Your volt pen will show a live as they have a perm live going to them for the microswitch. You'd need to see if there's 240v on the Brown wire to the motor to work out if it's wired incorrectly.

                Comment

                • Mark Had
                  Automated Home Lurker
                  • Nov 2021
                  • 6

                  #10
                  My pen tells me that pretty much every cable is busy beeping except the earth connecting to the casing.

                  Comment

                  • Somebody
                    Automated Home Sr Member
                    • Feb 2019
                    • 78

                    #11
                    Happened to me. Was the temperature sensor probe for the cylinder tank that connects to the CS92.

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