Efficiency of a MTD Collector vs a copper tubing / aluminum fin collector

Discussion in 'Solar and Geothermal Water Heating Forum' started by wookinpanub, Sep 22, 2011.

  1. wookinpanub

    wookinpanub New Member

    Messages:
    1
    Location:
    Colorado
    Hi all,
    I'm going to be posting a few links for reference to my question, so let me first say that I am not affiliated with the linked site in anyway other than I have built some of the project designs in that past and found their free resources very useful. To my question.

    I'll be building a new construction house with many green design principles, one of them being solar hot water heating. My system was to be based on this design. It was relatively straightforward to build (I did it, although not fully installed yet), much cheaper than the similar commercial alternatives, and appears to be roughly as efficient. This was the design I was intending to use going forward until I came across this MTD (Modified Trickle Down) design as seen here.

    This MTD collector is appears to be even easier to assemble, cheaper in regards to materials - however what I cannot tell is how it stacks up efficiency wise for the same surface area? If the relative efficiencies between the two are within say 10-15% I would lean the MTD route given costs / ease of assembly. If I can get an efficiency uptick greater than that using a copper / aluminum fin design vs the MTD it would be worth it to me to build that type design instead.

    Anyone have a relative idea / comparison in these two designs for a similar surface area in the same conditions? Any help is appreciated!
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,270
    Location:
    Cave Creek, Arizona
    My initial impression is that, since heating water precipitates the minerals in suspension, the "felt" or other absorptive material, would eventually become coated/clogged and lose its effectiveness, similar to the pads in a "Master Cool" evaporative cooler. your link to your design does not work, but any copper/aluminum fin unit will work. The critical items are to have the entire assembly painted black for maximum absorbtion, and the water tubing as small as possible to give the maximum heat transfer.
    Last edited: Sep 24, 2011
  3. leaualorin

    leaualorin New Member

    Messages:
    2
    Location:
    Romania,Buzau county
    A 15 mm copper pipe could be considered BIG in diameter for this kind of things?
    I first thought of making the whole solar collector out of 15mm diameter ,30 meters of copper pipe to have a surface area of at least 1 square meter!(this design would have a 1,2 square meter area).
    I too believe that copper pipe is the best for a solar collector but the price is the main problem to it!
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