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Evacuated tube failure

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Our system is now about 15 years old and produces next to no hot water. After checking it, we disconnected one tube from the manifold. The copper bulb in it was cold. This would point to a failure of the tube(s). Has anyone else seen that?

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  • pecmsg
    pecmsg Member Posts: 4,967
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    I need to see pictures of this tube!
    HomerJSmith
  • hot_rod
    hot_rod Member Posts: 22,491
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    Sounds like a heat pipe type of evac tube. Is the glass cloudy? That indicates it has lost it's vacuum. It should still get a bit above ambient and feel warm on the bulb.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,251
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    Haven't seen them "degrade" like that just B-52 strikes from the Seagulls. Yep picture would be great   Mad Dog 🐕 
  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    Yes.. We have seen massive failures on Vacuume tube type collectors in high attitude installs
    Thermomax and Viessmann both used Kingspan to produce the tubes that did not last very long..
    Additionally: If the tubes are subject to prolonged stagnating temperatures they do not hold up and "Burn out"
    Apparently Viessmann now offers a better tube as replacement.
    We will be removing a 30 tube system in about 4 weeks.
  • kcopp
    kcopp Member Posts: 4,450
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    Yes.. We have seen massive failures on Vacuume tube type collectors in high attitude installs
    Thermomax and Viessmann both used Kingspan to produce the tubes that did not last very long..
    Additionally: If the tubes are subject to prolonged stagnating temperatures they do not hold up and "Burn out"
    Apparently Viessmann now offers a better tube as replacement.
    We will be removing a 30 tube system in about 4 weeks.

    Are you replacing?
    Or are they doing PV instead?
  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    kcopp said:

    Yes.. We have seen massive failures on Vacuume tube type collectors in high attitude installs
    Thermomax and Viessmann both used Kingspan to produce the tubes that did not last very long..
    Additionally: If the tubes are subject to prolonged stagnating temperatures they do not hold up and "Burn out"
    Apparently Viessmann now offers a better tube as replacement.
    We will be removing a 30 tube system in about 4 weeks.

    Are you replacing?
    Or are they doing PV instead?
    We did a solar pathfinder study and shading was a factor that also warrants the removal.
    Trees and mountains would have to be removed.
    The original uneducated installer increased the customers carbon footprint.. :/

    Mad Dog_2
  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    BTW... The replacemenmet Tubes are very pricey
    Flatplates such as Sunearth produces are our goto preferably in a Drainback setup.
    Theealchemist
  • hot_rod
    hot_rod Member Posts: 22,491
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    there is not a lot of additional energy available from tubes compared to flat plate
    cold ambient, below 20F, is about where tubes start to have some advantage

    The formula takes into account ambient and collector inlet temperature, divided by solar radiation

    with the heat pipe style evac tubes you have two vacuums to maintain. The tube itself, and there is vacuum pulled inside those copper heat pipe bulbs. That allows the water alcohol mix inside to boil around 110F

    It flashes to steam and that is how the copper bulb can get to 300F plus temperature

    It is hard to know when the vacuum in the copper heat pipe is gone. 

    Looking at the array with an infrared camera will show the tubes that have gone bad. Without getting on the roof or removing the tubes from the header.


    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,251
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    The Buderus Flat Panels seemed well made but I forgot who made them for them...I remember the Solar HW classes 25 yrs ago comparing Flat Panel style versus Evacuated Tubes...Evac. tubes definitely outperformed
    FP.   That being  said, anything by The Salt water (Seagulls) is going to get beat up much faster when they constantly drop their payload (Quohogues) big clams..on the Evac. Tubes...You'd think they could make a more durable glass?? I'm sure, heat transfer, convection et al, are the reason...price too   mad 🐕