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Rank 6
James_N
Rank 6
October 25, 2021
Solved

Hot water and heating control with my Mitsubishi Ecodan Air-Source Heat Pump (ASHP)?

  • October 25, 2021
  • 81 replies
  • 18264 views

Hi there,

 

I’ve been looking at some of the data coming from my EcoDan system. 

Something you can see here just looking at the tank temp maroon line at the top (chart is last 24 hours of time). At around midnight the HW temp falls to about 40 degrees which triggers the pump to bring it back up to 50. The temp then falls back across late night / early morning. Given I know no one is going to use the HW until 7am, is heating up at midnight a waste? It seems like that intially, but then you have to factor in that the tank temp would still fall further if not reheated at midnight. 
 

Wondering if I could / should stop the HW heating up at midnight? (Of course if I had a nighttime elec tariff this could be a better strategy)

 

    Best answer by Speps

    You can do two things to stop this.

    Firstly is to look at and adjust the reheat temperature, which is the temperature below the set point that the tank will heat up. These graphs don't tell the whole story but it looks like yours is very aggressive, 5 degrees or less? Try 10 or even 12 degrees.

    Second thing you can do is to adjust the hot water timer so it doesn't go on overnight.

    I use this timer to stop the hot water from reheating in the morning, as otherwise a few morning showers will stop the central heating and interferes with the heating schedule. But I would not suggest this for your fix as there will be times you empty the tank before bed and need it in the morning.

    I've attached my graph of the same. By chance it also shows a leigionella boost. Its strange your graph doesn't show the boiler set point? 

    Another warning not to take these graphs as 100% accurate for temperature, as I had a shower last night and it was definitely warmer than the 20 degrees it says my tank was.

     

    81 replies

    Show previous replies
    Tim_OVO
    OVO Staff
    Tim_OVO
    OVO Forum Legend
    September 6, 2022

    Hi @Oz182uk - thanks for posting this. 

     

    Do you have an air source heat pump? Can you tell us a little bit more about your home set up and the issue, and I’ll know which members may be able to help...

    Carbon neutral - we need a community to get there! My green tech: Aclara SGM 1411-B smart meter, Chameleon IHD6
    H
    Newcomer
    haze146
    Newcomer
    December 2, 2022

    Hi,

     

    i am not sure if anyone can help with our mitsubishi ashp.

    We moved in 2020 (new build) did not get shown how to use heating system. I have watched you tube videos but they are too general and do not really give me enough information.

     

    I have ‘set it up’ best i can but feel were using a-lot of electricity but the house feels cold.  
    We are 2 bed semi detached, underfloor heating downstairs, radiators upstairs and have thermostats in each room.

    I have also contacted mitsubishi but they just sent me a general guide which didnt really help at all.

    Thank you! 

    Blastoise186
    Super User
    Blastoise186Super User
    Super User
    December 2, 2022

    Hey @haze146 !

    Sure thing. Let me see if @M.isterW is around as I think he can figure this out better than I can.

    Bear with us!

    Securing energy by zapping security bugs... For that is The Blastoise Way! Remember, I'm just like you - AI Powered Evil Geniuses aren't Staff!
      M.isterW
      Rank 6
      M.isterW
      Rank 6
      December 2, 2022

      The first thing to do, if you haven't already, is find Heat Geek on YouTube and watch their videos on heat pumps. You're looking for videos about zoning, weather compensation and running at lowest flow temperature. While you're there it's also worth checking out what they have to say about hot water temperatures. I think @juliamc had a link to an article they wrote on the subject.

      1992 4 bed detached house. Solar PV + battery, Zappi EV charger, Mitsubishi Ecodan ASHP and i-life2 fan assisted radiators.... No gas 😊
        juliamc
        Rank 20
        juliamc
        Rank 20
        December 2, 2022

        Possibly this one about legionella ? But all their articles are very informative. 
        https://www.heatgeek.com/hot-water-temperature-scalding-and-legionella/

          M.isterW
          Rank 6
          M.isterW
          Rank 6
          December 2, 2022

          How are you running the system at the moment?

          1992 4 bed detached house. Solar PV + battery, Zappi EV charger, Mitsubishi Ecodan ASHP and i-life2 fan assisted radiators.... No gas 😊
          B
          Newcomer
          Bfg74
          Newcomer
          December 12, 2022

          The outdoor install isn't much better with bare sections, gaps and gaping on the bends.

          Should I try and get the installer back to sort these issues?

           

          The pipe lagging should have no gaps but also it should be painted with Armaflex UV paint to prevent it degrading in the sunlight. The other problem which may cause a board fault in the future is that they’ve run the power cables into the top of the switch. Over time if the water seal degrades and a neutral fault occurs it will be an expensive call out for new circuit boards.

            C
            Newcomer
            Caroline2000
            Newcomer
            June 12, 2023

            It’s summer here and hot; so haven’t used the underfloor heating since April.

            Yesterday we had no hot water when we turned hot taps on. It’s was reading 16 degrees.

            System automatically goes to immersion but doesn’t heat up either.

            Turned U/F heating on and that works fine.

            Had an electrician out tonight and he checked voltage over pump - none - checked spur and fuse has gone!

            He then checked pump (attached to tank) and no voltage going to it - so where would supply be coming from?

            Could it be a problem with the circuit board attached to tank?

            Managed to get the immersion to turn on to get some hot water - but obviously not an ideal solution…..

            EDIT: it’s the 14kw product

            juliamc
            Rank 20
            juliamc
            Rank 20
            June 12, 2023

            @M.isterW our resident ecodan owner ! Any thoughts ?

              M.isterW
              Rank 6
              M.isterW
              Rank 6
              June 13, 2023

              I'm no expert but it sounds like either a fault with the controller or the circulation pump.

               

              Have you tried turning the water on from the FTC controller and Melcloud?

              1992 4 bed detached house. Solar PV + battery, Zappi EV charger, Mitsubishi Ecodan ASHP and i-life2 fan assisted radiators.... No gas 😊
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