Fun with a MAIN Unvented hot water cylinder

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  • Nad
    Automated Home Guru
    • Jul 2008
    • 145

    Fun with a MAIN Unvented hot water cylinder

    Hi all,

    We've had one of the above units installed and it looks like there is nowhere to get a temperature reading out to Cortex from. I spoke to their technical support and they said the only option is to put the sensor on the outlet ... which is fine if I only wanted flow temperature. Anyone have any bright ideas? I asked about making a hole in the insulation jacket and he didn't sound too impressed with that.

    Thanks,
    Nad
  • chris_j_hunter
    Automated Home Legend
    • Dec 2007
    • 1713

    #2
    ours had pockets for sensors - we also added clip-on sensors on the pipes, which of course need flow to be accurate (no flow, and they gradually move to room temperature), but we added logic to freeze the readings for a while ... works well-enough, so long as water is used not too infrequently - meaning, at first in the morning can be unrepresentative, depending on the logic & time constants ... could correct that, though, with some experimenting (ie: to know how temperatures fall over time when no water used) ...
    Our self-build - going further with HA...

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    • M.Harrison
      Automated Home Jr Member
      • May 2016
      • 33

      #3
      Hi - I had the same issue - Ended up attaching the thermistors to the side of the nuts of the tank couplings (as close as I could get to the body of the tank) with some heat transfer compound and a cable tie then wrapping the whole area with pipe insulation... Rather crude but it does seem to work as long as you allow for the fluctuations caused by flow... I've used 2 sensors, one on the inlet & one on the outlet and then use some logic gates to manage it. Firstly a mux gate to get an average temperature, then for the heating trigger it goes into the time accumulation logic so that the temp has to be below the set level for over 10 mins (i.e. its a real temperature not just someone washing their hands!!!). Not particularly elegant but it does seem to work - Any peaks in outlet temp do seem to be balanced out by the drop in temp at the inlet as fresh cold water flows in...

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