dehumidifiers

>There have been lots of posts about how crappy the Kenmore 70 pint
>dehumidifiers have turned out to be. Mine broke every year for
>the 3 years I kept it...

| --> dry air

> >There have been lots of posts about how crappy the Kenmore 70 pint
> >dehumidifiers have turned out to be. Mine broke every year for
> >the 3 years I kept it...
> And they use lots of electrical energy. A Smart Vent (40 watts max)
> would probably last longer. It has an electronic circuit that turns
> on 2 small fans whenever the dew point of outdoor air is less than
> the dew point of indoor air, ie the absolute humidity of the outdoor
> air is lower. The Zomeworks H2 ventilator for battery boxes seems
> to do the same thing, something like this, viewed in a fixed font:
> outdoors up indoors
> ---------------
> <-- moist air
> ----------------------
> | --> dry air
> | -------------------
> | |
> | | ---------------
> | | heat exchanger
> | |
> | | down
> | |
> | | dip tube
> as described in Steve Baer's ASES 2004 Humidity Chimneys paper. Moist air
> is less dense than dry air, at the same temperature (hence the heat
> exchanger.) Steve says a 1% moisture difference with a 2.5 foot height
> difference (hence the dip tube) can make 75 feet per minute of air flow,
> so a 6" pipe with an 8' height might make Pi(3/12)^2sqrt(8/2.5)75 = 26 cfm
> flow and remove about 26x60x0.075x0.01x24h = 28 pints per day of water
> from a basement, in dry weather, with a concentric pipe heat exchange
> chimney inside the house, from the first floor ceiling to the basement.
> The external "dip tube" might be a box with a transparent south side
> and 150 Tyvek bags filled with desiccant clay, which can absorb 28%
> of their weight in water, ie 53 pints:
> http://www.uline.com/ProductDetail.asp?model=S-1606&ref=1006
> The Florida Solar Energy Center puts clay bags on wire racks in an attic
> with a tin roof which heats up and dries them out during the day. After
> they cool, at night, they remove moisture from house air that circulates
> up through the attic. Here's some Desi-Pak (tm) tech info:
> http://www.agmcontainer.com/desiccantcity/pdfs/Desiccant%20performanc...
> Graph 4 shows Desi-Paks can absorb 12% of their weight in 10 hours
> at 30C and 60% RH, ie 2.3 pints per hour for the 189 pound collection
> above. This rises with more airflow or thinner bags. Graph 3 says
> they can absorb 8% in 100 hours at 25C and 10% RH, ie 0.15 pints
> per hour for 189 pounds.
> Nick

>I have a Sears dehumifier that is 20 years old, it had the fan go once
>($100 fan). The problem I see with drawing hot dry air from an attic
>is, it would make the basement hot. I enjoy my cool / semi dry
>basement because of the dehumifier. I can't see desicant doing the job
>a dehumifier does..... It may work but I doubt it would be an easy
>install.
>On Jun 19, 6:01 am, nicksans...@ece.villanova.edu wrote:
>> >There have been lots of posts about how crappy the Kenmore 70 pint
>> >dehumidifiers have turned out to be. Mine broke every year for
>> >the 3 years I kept it...
>> And they use lots of electrical energy. A Smart Vent (40 watts max)
>> would probably last longer. It has an electronic circuit that turns
>> on 2 small fans whenever the dew point of outdoor air is less than
>> the dew point of indoor air, ie the absolute humidity of the outdoor
>> air is lower. The Zomeworks H2 ventilator for battery boxes seems
>> to do the same thing, something like this, viewed in a fixed font:
>> outdoors up indoors
>> ---------------
>> <-- moist air
>> ----------------------
>> | --> dry air
>> | -------------------
>> | |
>> | | ---------------
>> | | heat exchanger
>> | |
>> | | down
>> | |
>> | | dip tube
>> as described in Steve Baer's ASES 2004 Humidity Chimneys paper. Moist air
>> is less dense than dry air, at the same temperature (hence the heat
>> exchanger.) Steve says a 1% moisture difference with a 2.5 foot height
>> difference (hence the dip tube) can make 75 feet per minute of air flow,
>> so a 6" pipe with an 8' height might make Pi(3/12)^2sqrt(8/2.5)75 = 26 cfm
>> flow and remove about 26x60x0.075x0.01x24h = 28 pints per day of water
>> from a basement, in dry weather, with a concentric pipe heat exchange
>> chimney inside the house, from the first floor ceiling to the basement.
>> The external "dip tube" might be a box with a transparent south side
>> and 150 Tyvek bags filled with desiccant clay, which can absorb 28%
>> of their weight in water, ie 53 pints:
>> http://www.uline.com/ProductDetail.asp?model=S-1606&ref=1006
>> The Florida Solar Energy Center puts clay bags on wire racks in an attic
>> with a tin roof which heats up and dries them out during the day. After
>> they cool, at night, they remove moisture from house air that circulates
>> up through the attic. Here's some Desi-Pak (tm) tech info:
>> http://www.agmcontainer.com/desiccantcity/pdfs/Desiccant%20performanc...
>> Graph 4 shows Desi-Paks can absorb 12% of their weight in 10 hours
>> at 30C and 60% RH, ie 2.3 pints per hour for the 189 pound collection
>> above. This rises with more airflow or thinner bags. Graph 3 says
>> they can absorb 8% in 100 hours at 25C and 10% RH, ie 0.15 pints
>> per hour for 189 pounds.
>> Nick

> Nick has a "thing" for this gadget and is rehashing a "discussion" we had
> last
> winter. He exaggerates the "badness" of dehumidifiers and IMO,
> exaggerates the
> goodness of his pet gadget.
> I've measured my mid-quality GE dehumidifier using the equipment and
> techniques
> described here:
> http://www.neon-john.com/Misc/Energy_Audit.htm
> Feel free to download and use my spreadsheet. Bottom line, measuring long
> term from
> 11/04/06 to 04/23/07, my dehumidifier used 2.03 KWH per day or about 15
> cents' worth
> of power at our rate. The watt-hour meter is still connected and come
> November, I'll
> have a year's worth of data. I suspect that Nick's gadget will operate in
> the same
> ballpark of energy consumption. Meanwhile, my basement is both cool AND
> precisely
> controlled to 50% humidity. Me and my fairly large library love it.
> There are more efficient dehumidifers available but as I correctly
> anticipated, the
> savings would take a lifetime to make up the difference in costs of the
> machines.
> John
> wrote:
>>I have a Sears dehumifier that is 20 years old, it had the fan go once
>>($100 fan). The problem I see with drawing hot dry air from an attic
>>is, it would make the basement hot. I enjoy my cool / semi dry
>>basement because of the dehumifier. I can't see desicant doing the job
>>a dehumifier does..... It may work but I doubt it would be an easy
>>install.
>>On Jun 19, 6:01 am, nicksans...@ece.villanova.edu wrote:
>>> >There have been lots of posts about how crappy the Kenmore 70 pint
>>> >dehumidifiers have turned out to be. Mine broke every year for
>>> >the 3 years I kept it...
>>> And they use lots of electrical energy. A Smart Vent (40 watts max)
>>> would probably last longer. It has an electronic circuit that turns
>>> on 2 small fans whenever the dew point of outdoor air is less than
>>> the dew point of indoor air, ie the absolute humidity of the outdoor
>>> air is lower. The Zomeworks H2 ventilator for battery boxes seems
>>> to do the same thing, something like this, viewed in a fixed font:
>>> outdoors up indoors
>>> ---------------
>>> <-- moist air
>>> ----------------------
>>> | --> dry air
>>> | -------------------
>>> | |
>>> | | ---------------
>>> | | heat exchanger
>>> | |
>>> | | down
>>> | |
>>> | | dip tube
>>> as described in Steve Baer's ASES 2004 Humidity Chimneys paper. Moist
>>> air
>>> is less dense than dry air, at the same temperature (hence the heat
>>> exchanger.) Steve says a 1% moisture difference with a 2.5 foot height
>>> difference (hence the dip tube) can make 75 feet per minute of air flow,
>>> so a 6" pipe with an 8' height might make Pi(3/12)^2sqrt(8/2.5)75 = 26
>>> cfm
>>> flow and remove about 26x60x0.075x0.01x24h = 28 pints per day of water
>>> from a basement, in dry weather, with a concentric pipe heat exchange
>>> chimney inside the house, from the first floor ceiling to the basement.
>>> The external "dip tube" might be a box with a transparent south side
>>> and 150 Tyvek bags filled with desiccant clay, which can absorb 28%
>>> of their weight in water, ie 53 pints:
>>> http://www.uline.com/ProductDetail.asp?model=S-1606&ref=1006
>>> The Florida Solar Energy Center puts clay bags on wire racks in an attic
>>> with a tin roof which heats up and dries them out during the day. After
>>> they cool, at night, they remove moisture from house air that circulates
>>> up through the attic. Here's some Desi-Pak (tm) tech info:
>>> http://www.agmcontainer.com/desiccantcity/pdfs/Desiccant%20performanc...
>>> Graph 4 shows Desi-Paks can absorb 12% of their weight in 10 hours
>>> at 30C and 60% RH, ie 2.3 pints per hour for the 189 pound collection
>>> above. This rises with more airflow or thinner bags. Graph 3 says
>>> they can absorb 8% in 100 hours at 25C and 10% RH, ie 0.15 pints
>>> per hour for 189 pounds.
>>> Nick
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Cleveland, Occupied TN
> Remember, amateurs made the Ark, professionals made the Titanic.
>