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Most “efficient” location for a dehumidifier in a house

Josh Durston | Posted in Energy Efficiency and Durability on

I run a portable dehumidifier probably 60% of the year in my bungalow.

I was wondering how much the ambient conditions affect efficiency?
The dewpoint of the air in the house is relatively constant, but the %rh is higher in the basement due to lower temperatures.

Is it best to minimize the sensible load on the dehumidifier by placing where the ambient temperature is closest to the dewpoint (assuming a constant dewpoint)?   Or will the lower ambient temperature (maybe 19C instead of 22C upstairs), cause the dehumidifier to cycle more for frost protection?

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  1. Jon R | | #1

    The dehumidifier has to cool the air to remove moisture. The basement air is partially pre-cooled, so dehumidifying it is more efficient. I suspect not by much.

  2. Charlie Sullivan | | #2

    I had saved some extended dehumidifier data that someone had posted here before, and I too a look. The trend is very clearly as Jon says, and it actually makes a bigger difference than I would have thought. 65 F dry bulb, 51 dew point, 60 % humidity it's 5.23 pints/kWh. Whereas 70 F, 50 dew point 50% RH, it's 4.07 pints/kWh. 70% humidity at 60 F, 50 DP, it goes up to 5.74, and 80% humidity at 55 F, for a 49 DP gives 6.42 pints/ kWh.

    But if you just look at a given RH, the best performance is around 85 F. 85 F at 80% humidity and you get 8.7 pints/kWh.

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