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Deficiency of Evacuted tubes V Flat panel. Never seen this discussed

Discussion in 'Living Room' started by redsquash2, 31st Oct, 2015.

  1. redsquash2

    redsquash2 Member

    Joined:
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    Location:
    Brisbane
    For Brisbane climate only.
    The later models of the Solar HWS with evacuated tubes have the pumps cutting off when the water temperature hits 70 degrees, I believe. Also what portion of the tank is 70 degrees ?

    The Flat panel solar HWS using thermosyphen principles and no pump just continuously heat up the water making the whole tank hotter.It never switches off until the sun disappears.

    Ignoring other considerations wouldn't this make the Flat Panel solar HWS better on most days in terms of the total volume of hot water heated. The whole tank, in theory is heated to the same temperature.

    In addition there is almost nothing to break down with flat panel systems , no controller electronics or pump
    Up until now I was strongly in favour of replacing my flat panel system with evacuated tube system.
    I would be really interested in a technical reply . I have never seen this discussed anywhere.
    BTW if in a Canadian climate I would jump on Evacuated tubes.
     
  2. B-Man

    B-Man Well-Known Member

    Joined:
    18th Jun, 2015
    Posts:
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    Location:
    SA
    i looked into this a bit. and im getting a thurmann (made by apricus for reece)
    the basics are:

    -the ET is a lot more efficient as it has passive sun tracking (since they are round) it can start working earlier and finish later than a FP.
    - will work better in winter and in colder climates - (i see your in brisbane so a FP might be fine there)

    http://www.apricus.com.au/apricus-solar-collector/
    ET vs FP pdf
    http://www.apricus.com.au/downloads/

    as for your question i think its the bottom sensor in the tank that would cut it off at the 70°
     
  3. redsquash2

    redsquash2 Member

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    Location:
    Brisbane
    Hi B-Man
    I have seen lots of similar data over the years but most owners will tell you the pump only runs a few hours a day.
    It seems irrelevant that passive tracking occurs as this is useless when the pump is not working ie the pump cuts out when tank is at 70 degrees.Yes tubes seem more efficient but not by how much the graphs indicate , if the water isn't flowing in the tubes. Apart from about 7 weeks in a Brisbane winter I suspect the differences may not be so much as is commonly thought.
    BTW My marine grade steel tank is doing just fine after 20 years with flat panels
     
    Last edited: 1st Nov, 2015
  4. B-Man

    B-Man Well-Known Member

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    SA
    in a colder climate it would be beneficial
    i guess if the pumps not running the waters already hot.
    i have also read that some don't cut out until 85°

    like i said it would depend on the climate its just like a heat pump works better in darwin than it would in melbourne. (not actually recommended for rec zone 4)
    a flat panel might be fine in darwin but not in melbourne.
    where as an evacuated tube works good in melbourne and great in darwin but its unneeded as the flat panel is sufficient.
     
  5. Tim86

    Tim86 Well-Known Member

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    Location:
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    I hate Apricus. I hate evacuated tube systems.

    I have a house with a cheap flat panel system on it and I've got my PPOR with an Apricus system on it. I thought I would go for the expensive one for my house. I think it cost me $3500. The flat panel system cost around $1200.

    The flat panel outperforms the apricus system hands down. Day in day out, for years.

    You will need to have your booster on your apricus system for about 3/4 of the year... even with Brisbane weather. If you don't put your booster on off peak, you end up using MUCH more electricity with a boosted apricus system than you do with a $600 stock standard electric hot water system.

    I tried to get a refund for my apricus system because it is a heap of junk, but they refused. Now I just have it constantly boosted on off peak. I'd be surprised if I even save $20 in electricity per year because of it. If you have a household of 4 or more people and you want a shower of approx 10 mins each in winter, forget it, you'll run out of hot water with an apricus system, because the booster is only part way up the tank so doesn't actually heat the whole thing.

    I've had the apricus maintenance people out here because I thought surely something was wrong with the system. They said "that's just the way it is. Don't think of it as a solar hot water system. Think of it as an electric hot water system, that sometimes gets boosted by the sun". I kid you not, that's what their repairer told me!

    I've had so many cold showers because of my "fancy" expensive apricus system.

    I would HIGHLY recommend just getting a big solar electricity system and a normal electric hot water system. Use the solar electricity to power your electric hot water system plus the rest of your house. Will cost the same price too!

    The guy that supplied me the apricus system and talked me into spending the extra for it... DOESN'T EVEN SELL THEM ANY MORE. He has gone back to the flat panel systems because now he says the apricus systems are a heap of trouble. Wish he told me that when he sold me it, rather than telling me how "amazing" it was.

    Plus you better hope you never get hail. A flat panel system will be fine in hail, but a light hail storm will smash out about 6 tubes in a 30 tube system.

    Dismiss me if you want. But you have been warned. Genuinely the worst purchase I have EVER made.
     
  6. B-Man

    B-Man Well-Known Member

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    SA
    theres heaps of ET around here and havent heard a bad thing from any of the locals.
    have read on some other posts that people have had trouble. im guessing much of it comes down to installers

    also i do agree on your comment of getting a solar panel system and a std electric HWS but on new builds your not allowed to otherwise thats what i would of gone with
     
  7. Tillie

    Tillie Well-Known Member

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    I believe that you have something wrong with your system. We had a 'tube' solar hot water system in our previous PPOR and booster was required only some days during Melbourne winter. But over 9 months of the year not required.
     
  8. Tim86

    Tim86 Well-Known Member

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    I had the installers out twice. And had the apricus plumbers out as well. They all said there is nothing wrong with it. The apricus plumber said he has the same system and has to put the booster on for the entire winter. Thats brisbane winter mind you. The sort of weather where if its a really "cold" day you have to wear a t shirt instead of a singlet and put socks on before you pop on your thongs.

    I dont know why yours had no problems. Ive got a flat pannel system on the house next door which is way better than the evacuated tube system I have on my ppor. Obviously exact same conditions as its right next door.

    Anyway I could complain forever about my stupid hot water system... but I probably should stop.