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    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012 edited
     
    Some of you may have noticed that I have been talking about making a MVHR unit. Well this is the data my first attempt.
    It currently has no control over the incoming air (cold), the outgoing air (hot) is on a timer on the bathroom fan. You can see exactly when the bathroom is used on this chart and work out how much tea I drink if you are so minded.
    Between 10:10 and 11:15 I kept the fan on constantly. The two spike before hand were shower times, guess who has the smaller spike?

    The unit is pretty basic, just some plates in a box, a couple of fans and some pipe. Lots of room for improvement, tomorrow I shall go and get another fan with a timer on it.
    Comments and suggestions welcome.

    Efficiency has been calculated this way:
    μt = (t2 - t1) / (t3 - t1)
    where
    μt = temperature transfer efficiency
    t1 = temperature outside air before the heat exchanger (ºC)
    t2 = temperature outside air after the heat exchanger (ºC)
    t3 = temperature inside air before the heat exchanger (ºC)
     
     
      First Chart No Control.jpg
    • CommentAuthorEd Davies
    • CommentTimeFeb 22nd 2012
     
    “Cold in” = t1, “Hot in” = t2?

    Sorry, it was very mild here yesterday but I've no idea what temperatures were like at the other end of the island so it's difficult to be sure if that makes sense.

    Still, 60 to 70% efficiency on a first attempt seems pretty encouraging. Look forward to more and piccies.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012 edited
     
    I think, because there are no baffles/flaps, and there is a ±0.5 on the iButtons also sods law being what it is, plus up to a minute out on the temperature reading that the accuracy is not that great (5 minute sampling). After tomorrow when I get a new fan should yield some better results.

    Just used http://www.engineeringtoolbox.com/heat-recovery-efficiency-d_201.html for the efficiency calculations.
    Think that should be the classic 'up to' on the efficiency, you do get the greater efficiency with the lowest energy recovery by the looks of it.

    This is the real outside temperature.
     
     
      External Temp 21-02 to 22-02.jpg
    •  
      CommentAuthorjoe90
    • CommentTimeFeb 22nd 2012
     
    I love it, I am a real build it yourself fan and love what you are doing, I may not understand all the "numbers" but I will leave that to you and others as long as you post you're design for the unit and how you built it.:bigsmile:
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    I better get working on the CAD then. Thanks
    • CommentAuthorRobL
    • CommentTimeFeb 22nd 2012
     
    Hi ST - Am impressed that you're having a go with this!
    Our MVHR unit (vent axia sentinel kinetic plus) uses thin plastic as the heat exchanger. From memory the heat exchanger's about 25*25*25cm in size & looks like it's made of a million straws. What material and construction are you using?
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    Painted steel plates, expanded polyurethane sheet (celotex like), silicone sealant, some 150 plastic pipe, some flexible pipe, couple of bathroom fans and a cut finger.
    MkII will be a lot better.
    I have drawn it up in Turbocad 17 but shall post it up here as a sketchup file (if I can zip it enough).
    But here is a picture to be going on with.
     
     
     
      First Picture.jpg
    • CommentAuthorCav8andrew
    • CommentTimeFeb 22nd 2012
     
    Steamy Tea, you weren't set designer on early Doctor Who series by any chance ?
    •  
      CommentAuthorCitrus
    • CommentTimeFeb 22nd 2012
     
    Posted By: joe90I love it, I am a real build it yourself fan and love what you are doing, I may not understand all the "numbers" but I will leave that to you and others as long as you post you're design for the unit and how you built it.:bigsmile:" alt=":bigsmile:" src="http:///forum114/extensions/Vanillacons/smilies/standard/bigsmile.gif" >


    Totally what he said.

    I never understand all the maths, but show me a diagram and I'm away. Thank heavens there are people as awesome as the OP to work these things out. Thank you :D
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    Won't let me upload it as a zip today:sad:
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012 edited
     
    Posted By: Cav8andrewyou weren't set designer on early Doctor Who series by any chance

    Funny you should mention that, I have done some film work in the past and made a Dalek once. Did the helmets for Krull and some reindeer parts for Santa Klaus the Movie. That brings back memories.
    Give me an 8 by 4 sheet and I can make anything :wink:
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    Just make sure you measure your loft hatch first :bigsmile:
    • CommentAuthorCav8andrew
    • CommentTimeFeb 22nd 2012
     
    Alien V ST MVHR I see a franchise !
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    Try this, says it accepts RAR files.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    Posted By: Cav8andrewAlien V ST MVHR I see a franchise !

    I see another cut finger:shamed:
    •  
      CommentAuthorCitrus
    • CommentTimeFeb 22nd 2012
     
    I can't get the RAR to open. Might just be me though.
    •  
      CommentAuthorjoe90
    • CommentTimeFeb 22nd 2012
     
    and me:shamed:
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012 edited
     
    Who knows, it opens here, is it a similar problem that we had with Jeremy's zipped files?
    I have a windows live account, shall see if I can get the files up there.
    • CommentAuthorBeau
    • CommentTimeFeb 22nd 2012
     
    Me too. Any chance you put a copy in the scetchup 3D warehouse.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 22nd 2012
     
    • CommentAuthorEd Davies
    • CommentTimeFeb 22nd 2012 edited
     
    Or this:

    http://www.greenbuildingforum.co.uk/newforum/?PostBackAction=Download&AttachmentID=2741

    but not this:

    http://www.greenbuildingforum.co.uk/forum114/?PostBackAction=Download&AttachmentID=2741

    ST: “is it a similar problem that we had with Jeremy's zipped files?”

    Yes. “forum114” version has the same line-feed character stuck on the beginning which upset the archive manager for me. Downloading the “newforum” version opened in the archive manager then double clicking on the .skp file opened it in SketchUp just fine.

    I'd strongly recommend the use of layers in SketchUp to allow showing cutaway drawings easily.
    • CommentAuthorCav8andrew
    • CommentTimeFeb 23rd 2012
     
    Has anyone been able to open ST's sketchup file or is it just me showing my usual computer skills (lack of)
    • CommentAuthorBeau
    • CommentTimeFeb 23rd 2012
     
    Opens fine for me in sketchup.
    • CommentAuthorCav8andrew
    • CommentTimeFeb 23rd 2012
     
    just me then!
    • CommentAuthorBeau
    • CommentTimeFeb 23rd 2012
     
    Andrew it has opened in my sketchup. Have you got sketchup?
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 23rd 2012 edited
     
    I don't have sketchup, does it open as a wireframe or a 3D fully rendered image?
    • CommentAuthorBeau
    • CommentTimeFeb 23rd 2012
     
    Full 3D that I can manipulate:devil:
    • CommentAuthorCav8andrew
    • CommentTimeFeb 23rd 2012
     
    Hi Beau, No, that's probably my first stumbling block !
    ST, will try again but did not appear to be opening but could well be me.
    • CommentAuthorrvb99
    • CommentTimeFeb 23rd 2012
     
    Hi, if anybody is interested here are some links to in France for a DIY MVHR - in France these are called "VMC - double flux" ( 2 way mechanical ventilators).

    http://vmc-double-flux-auto-construction.blogspot.com/

    there's another at http://www.autoconstruction.info/techniques/energie-chauffage-isolation/la-fabrication-d-un-recuperateur , which is built using honeycombe plastic pannels, rather than aluminimum.

    There's plenty of pictures, and if your French is not up to it, just use Chrome browser and click to translate it.

    regs

    Richard
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 23rd 2012
     
    Does make you wonder what advantage paying Vent-Axia gives you.
    Off to get second fan soon.:wink:
   
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