Hot Water overheating?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • basiluk
    Automated Home Sr Member
    • Oct 2008
    • 89

    Hot Water overheating?

    My previously stable Evohome setup is doing something wrong - Stored hot water temperature is reaching 71-77 degrees. Settings are as follows: Water temp 60 degrees, overrun = 10 minutes, differential is 10 degrees.

    Centra heating seems to be working fine. Anyone have any ideas?
  • DBMandrake
    Automated Home Legend
    • Sep 2014
    • 2361

    #2
    Why such a long overrun time ?

    The overrun is only to prevent the flow temperature in the boiler from peaking up high when both zone valves close and the flow is forced through a bypass loop. It gives enough time for latent heat to be removed from the boilers heat exchanger after turning of the burner but before closing the hot water valve.

    Anything beyond a couple of minutes probably doesn't do anything useful. I only have mine set to 1 minute...

    Do you graph your hot water temperature at all ? If so do you see a "sudden" jump in the reading from below 60 straight to 71-77 ?

    Comment

    • basiluk
      Automated Home Sr Member
      • Oct 2008
      • 89

      #3
      OK I will change the overrun time back. No idea how to graph the temp so cannot say when it happens. Happening every day now for three days.

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #4
        Keep an eye on the temperature reading next time it reheats.

        You'll probably find it jumps suddenly from a bit below 60 to over 70 degrees with no reading in between.

        Comment

        • basiluk
          Automated Home Sr Member
          • Oct 2008
          • 89

          #5
          OK, thanks - what does that indicate?

          Comment

          • DBMandrake
            Automated Home Legend
            • Sep 2014
            • 2361

            #6
            If your target is 60 and you see the reading jump suddenly from below 60 to over 70 it indicates comms issues from the CS92A sensor to the controller.

            Unfortunately there are many possible causes of this problem, many threads of discussion on here about these problems and no 100% resolution to the problem for some people - including me, as I still see occasional overshoots like this even after having the CS92A replaced under warranty, having moved it, replaced it's batteries, rebound it, etc etc.

            It might be worth checking the battery voltages though, and replacing the batteries if they are getting a bit low as there is some evidence to suggest the CS92A is very fussy about battery voltage.

            Comment

            • basiluk
              Automated Home Sr Member
              • Oct 2008
              • 89

              #7
              AH, now sorted - For whatever reason, (and I can't think of any) the hot water was coming on when the heating demanded boiler heat - Nothing changed for weeks, so no idea how it was caused.

              Well, full reset and rebind sorted it.

              Comment

              Working...
              X