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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorSprocket
    • CommentTimeDec 19th 2017 edited
    This is a bit TOO much DIY for me but I found it interesting nevertheless.
    I half expected to see a trade-bought or recovered industrial exchanger in this but I am quite surprised to see that even that is DIY.


    Hey SteamyTea... what happened with your DIY HRV build? Did that remain as an experiment or did you end up using it?
    • CommentAuthortony
    • CommentTimeDec 19th 2017
    Two fans in a box, filters and a nice simple heat exchanger simples, possible fire issues with wooden box, but I have seen them made of eps and plastic.

    Proper nice.
    • CommentTimeDec 19th 2017
    Right, but it's a cross-flow design rather than a counter-flow one, and the low efficiency indicates why counter-flow is better.
    • CommentAuthorSprocket
    • CommentTimeDec 20th 2017
    I've always been a bit suspicious of how some of these efficiency figures are calculated when I see 90%+ claims for MHRV. In a real working system there is often a large amount of water vapour and resulting condensation involved. That latent heat is a lot of energy so I would hope we get to recover that too.
    Our Xpelair MHRV has a hexagonal exchanger element in a close fitting polystyrene box. These "Lossnay" things are made of paper aren't they? How do they handle the water?
    Willie Mcleod has one and has no issues with water even with his Scottish climate
    • CommentAuthorMikC
    • CommentTimeDec 20th 2017
    I would have thought a DIY counterflowl heat exchanger would be trickier to build than a Crossflow, but if your going to all that effort it must be doable.

    I'm not sure how MHRV efficiency is measured but I think it's a bit of a grey area. LUNOS for example use a pair of crossflow exchangers working in tandem and claim 90% efficiency, I can't see this being meaningful myself.

    Is latent heat recovery accounted for in the testing of an MHRV unit? It seems to me like this is a must, otherwise we are not comparing apples to apples, so to speak.
    • CommentTimeDec 20th 2017 edited
    Posted By: SprocketHey SteamyTea... what happened with your DIY HRV build? Did that remain as an experiment or did you end up using it?
    Been up in the loft for years now, never check it though, probably full of fluff.
    I never really managed to get any decent data off it, something for a rainy day.
    That indistrucables design is not so different from mine.
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