Immersion heater located in the bottom of tank?

Discussion in 'Home energy' started by roker, Jun 13, 2018.

  1. roker

    roker Frequent Poster

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    As previously described, I have a solar heating system, the immersion is located in the bottom of the hot storage tank bellow the solar heating coils. This does not make sense to me because it will need to heat up the whole tank, should it not be installed near the top beside the boiler heating coils?
     
  2. huskerdu

    huskerdu Frequent Poster

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    When you say immersion, do you mean the solar coils which heat the water from the solar panel. If so, this is what I have, and it makes sense to me.

    Remember : Hot water will rise, but will not drop.

    A heating coil (of any kind : electric, gas, solar) at the bottom of the tank will heat the water at the bottom and this will rise and the temperature of the whole tank will rise.

    A heater at the top of the tank will heat the water at the top of the tank only and the water at the bottom of the tank will not heat.

    The solar coils at the bottom will heat the entire tank. I also have an electric and heater coils in the top half of the tank. They only heat the water above them so work faster, because there is less water to heat.
     
  3. Leo

    Leo Moderator

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    Electric elements are usually fitted in the top of tanks alright. Where there is a dual bath/sink type element, the more powerful bath element is longer and looped so that it runs down through the heating coils and a lot of its heating capacity is applied towards the bottom of the tank. The shorter, less powerful sink elements focus their out ut to the top third of the tank.

    Is there a second electric element entry option on your tank? Many such tanks will have that option, or the more traditional single top entry for a dual element electric element.

    With a solar system operating well, you'd imagine the greater need would be as a quick top up (and so upper element) rather than bringing a large volume up to heat with a lower element.
     
  4. roker

    roker Frequent Poster

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    Thanks, I am aware that on a normal tank there is a combine long and short element in the top of the tank named sink and bath. It makes no sense on my Grant solar system to have the element at the bottom below the solar coils, I would have thought it shoulds have been a top up for the solar system like you say. Grant are experts on these systems and must have a reason for putting one only element boss a the bottom.
     
  5. Leo

    Leo Moderator

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    They're an option for using electricity generated by PV panels to bring the water temp up, a dump of unused electricity generated due to no grid buy-back here.
     
  6. RETIRED2017

    RETIRED2017 Frequent Poster

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    Last edited: Jun 18, 2018 at 11:25 AM
    Why not contact makers and find out why seeing immersion is made in Ireland and share information back to forum, Do the do a system with an element boss at the top of cylinder,
     
    Last edited: Jun 18, 2018 at 11:25 AM
  7. RETIRED2017

    RETIRED2017 Frequent Poster

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    any word back from grant,
     
  8. Leo

    Leo Moderator

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    It's the installer you really need to speak to. Is it a Grant tank? Their DuoWave models seem to have the immersion element higher up.
     
  9. roker

    roker Frequent Poster

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    Grants reply:
    traditional copper cylinders the immersion was at the top, however when a solar system is installed it is legal requirement for legionella prevention to have the immersion at the bottom.
     
  10. Leo

    Leo Moderator

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    I'm not aware of any such legal requirement, a search via Google couldn't find anything either but I didn't spend too long at it. The SEAI just refer to a few technical guides, and these are mainly UK publications. If it were a legal requirement, how are they selling solar tanks with the factory fitted electric element in the upper half of the tank?

    Just adding an element to the bottom of the tank isn't going to achieve much unless it's used regularly