(Almost) Passive Cooling System

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2 Responses

  1. Felix says:


    Very interesting your cooling system. I´m planning something similar, also in a hot (and humid) climate in Southern Brazil. Question: How do you avoid mold build-up inside the hoses? How do you clean them, if at all? How did you determine the adequate diameter and quantity of hoses?

    Your help is very much appreciated. Regards,


    • Les Mulder says:

      Hi Felix,

      Hmm, yes, mould prevention – a detail missing from the description…
      the system is designed to allow moisture to run out the bottom of the pipes, first, at the bottom of the intakes, where any moisture that condenses as it goes down to the pipe at the bottom just drops out into a gravel trap at the very bottom of the intake pipe (it’s fully open at the bottom of the vertical section).
      There is also a series of small holes all the way along the bottom of the pipe. A circular saw was used to remove a 2mm deep section of the pipe all the way along the bottom – just deep enough to make a hole in the bottom of each corrugation, without slitting the pipe all the way through. These holes allow any moisture that didn’t drop out in the vertical section to drop out of the pipe along the way.
      There is no provision for cleaning.
      Pipe diameter was based on affordability more than anything else. We would have preferred one or two larger pipes with walls that transfer heat better than plastic does, but this was way too expensive.
      Finally to answer the question you didn’t ask, but probably should have, “does it really work for your house?”
      Only marginally. Our house is too big, has too many windows and leaks too much air for it to be truly effective. If your house is small, well insulated and sealed against the entry of hot air from outside, it’ll work great. I’m in the process of replacing some windows with mass walls to improve the house in hot weather, but I suspect I’m pushing poo uphill with a pointy stick…

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