Efficient ventilation mode?

Discussion in 'Gen 4 Prius Technical Discussion' started by Jeppefinn, Apr 7, 2018.

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  1. Jeppefinn

    Jeppefinn Active Member

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    Yup, hard to explain if you've never experienced it.
    But at -5C for example the relative humidity outside does not matter one bit.
    If you drive around and someone in the car is breathing (the driver or one of the passengers ;)) the outside air always contains less water even if relative humidity outside is 100%.
     
    #41 Jeppefinn, Apr 15, 2018
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  2. alanclarkeau

    alanclarkeau Senior Member

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    So better to have driver and passengers like this:
    upload_2018-4-16_7-48-58.png
     
    #42 alanclarkeau, Apr 15, 2018
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  3. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    We already have too many dummies driving here! :eek:
     
    #43 Prodigyplace, Apr 15, 2018
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  4. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes.

    Note that the dewpoint will rise slightly with the added water vapour so the difference between the temperature and dewpoint will decrease not only when you decrease the temperature but also when you add water vapour.

    There's some sort of standard to reading the thermometer. I recall a white box with slats to allow airflow and shade; that's where the thermometer resides.

    I'm guessing a surface reading will be false since there could be extra heat from the pavement or soil during the day.
     
    #44 Tideland Prius, Apr 15, 2018
  5. Jeppefinn

    Jeppefinn Active Member

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    Those guys look awfully happy and suspiciously chatty, we finns like our peace and quiet while driving.
     
    #45 Jeppefinn, Apr 16, 2018
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  6. Jeppefinn

    Jeppefinn Active Member

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    Yes, I think I've seen those official boxes too somewhere too.
    It's a ventilated white box about human head height from the ground and there should be no large pavements or parking lots nearby.
     
    #46 Jeppefinn, Apr 16, 2018
    Last edited: Apr 16, 2018
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  7. Jeppefinn

    Jeppefinn Active Member

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    I'll make you a video at -20C next winter. I think tit akes only 2 minutes if you go sit in a cold car and after that all the windows are fogged up from the inside (could be even less). At +10 it I bet it takes 10-15 minutes.
    (although me being a mouthbreather might make it worse :D)

    Putting a pan with boiling water in the cold car might make a cool youtube video come to think of it.
     
    #47 Jeppefinn, Apr 16, 2018
    Last edited: Apr 16, 2018
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  8. alanclarkeau

    alanclarkeau Senior Member

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    Yes, a Stephenson Box or Screen - we mounted ours at 1.5metres high from memory, but can't remember if that was top or bottom - probably bottom - there was some leeway in the standard.
    upload_2018-4-16_19-8-6.png
     
    #48 alanclarkeau, Apr 16, 2018
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  9. RCO

    RCO Senior Member

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    You're right, and I see Alan has already enlightened you. I won't bore you with the details, but the UK Met. Office has set Max/Min measurements for height above ground and distance clear of buildings an other obstructions. In case you're wondering, meteorology and basic forecasting are part of an air traffic controllers'training curriculum. In my day, you even had to receive & send in Morse code, but I don't suppose that's as necessary the days.
     
    #49 RCO, Apr 16, 2018
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  10. alanclarkeau

    alanclarkeau Senior Member

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    Morse Code was required for an Amateur (Ham) Radio licence till only about 15 yrs ago, though some countries were more recent - some may still require it.
     
    #50 alanclarkeau, Apr 16, 2018
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  11. Tideland Prius

    Tideland Prius Moderator of the North
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    No need. At -40, the top left part of my windshield never defrosted even though the climate control was set to the front defroster. I eventually accept that and went back to AUTO. This is in my Gen 3.

    Yes, that's what it's called! lol.
     
    #51 Tideland Prius, Apr 16, 2018
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