Evacuated tubes vs plate




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  1. #1
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    Default Evacuated tubes vs plate

    Does anybody know what the efficiency gains in heating water are when replacing a collector plate system(??) with a evacuated tube system?

    I have a solar system in place that increases water temp by max 20C on a hot day and I am considering replacing the collector with evacuated tubes.

  2. #2
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    Default Re: Evacuated tubes vs plate

    Evacuated tube collector is very efficient in situations where wind is a factor ( big heat loss from
    plate collector because no insulation on front) . Generally will outperform flat plate except in very hot
    ares with a lot of sunshine (such as inland N Cape or Namibia) . Only downside is , it is prone to overheating the water in the geyser if it is not used.
    I have been totally offgrid for 2 years now in Longbeach Namibia using, for hot water, a 20 tube collector and 150L tank and only have about 2 or 3 days a year when the water is below 40C .
    I have installed over 600 evacuated tube systems ( large and small) at the Namibian coast over the past 10 years and they are by far the the most used system here.

  3. #3
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    Default Re: Evacuated tubes vs plate

    Quote Originally Posted by kingchris View Post
    Evacuated tube collector is very efficient in situations where wind is a factor ( big heat loss from
    plate collector because no insulation on front) . Generally will outperform flat plate except in very hot
    ares with a lot of sunshine (such as inland N Cape or Namibia) . Only downside is , it is prone to overheating the water in the geyser if it is not used.
    I have been totally offgrid for 2 years now in Longbeach Namibia using, for hot water, a 20 tube collector and 150L tank and only have about 2 or 3 days a year when the water is below 40C .
    I have installed over 600 evacuated tube systems ( large and small) at the Namibian coast over the past 10 years and they are by far the the most used system here.
    I have a twenty five year old flat plate on my roof. How long do those tubes last.?

  4. #4
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    Default Re: Evacuated tubes vs plate

    Tubes are effective until they start degrading in SA's UV then you try and replace them ...

    If your plate collector is not installed in the correct orientation and correct angle to the ground level, it cannot absorb the maximum isolation possible.

    Also I quite commonly find that the plumbing make no provision for auto removal of air locks formed by steam generation. The result is severely restricted flow through the system.

  5. #5
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    Default Re: Evacuated tubes vs plate

    I started installing evac. tubes in 2007 and the lifespan is at least 10 years. Replacements are freely available from Kwikot . Recommended retail is R115.00 ex Vat

  6. #6
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    Default Re: Evacuated tubes vs plate

    I replaced my flat plate collector with a 20 tube system.Water is now heated from 15c to 50c between 9am and 5pm.

    In summer it might get too hot so ill have to make a plan then ...Very happy with my purchase. Hilton Melck on the forum did the installatikn for me, very knowledgeable and i can reccomend him 100 %!

  7. #7
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    Default Re: Evacuated tubes vs plate

    Replace your glycol.
    Don't feed the monkeys!

  8. #8
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    Default Re: Evacuated tubes vs plate

    Did replace the glycol after 7 years. Big difference in performance

  9. #9
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    Default Re: Evacuated tubes vs plate

    Evac tubes aren't as robust as the flat plate and therefore are easily damage by hailstones .Evac tubes only better on wintertime.

  10. #10
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    Default Re: Evacuated tubes vs plate

    Quote Originally Posted by Mbu View Post
    Evac tubes aren't as robust as the flat plate and therefore are easily damage by hailstones .Evac tubes only better on wintertime.
    During winter is when you really need efficiency.
    I was told that evacuated tubes are also more efficient in windy areas.
    2004 Defender 110 Td5


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