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 and even though the refrigeration system had 2 more years left on its warranty I decided I was tired of carrying it back to sears repair dept and this time, after it broke, I bought a Whirlpool. So far so good. Some people complain that the Whirlpool is noisy but I believe it is about the same noise level as the Kenmore. Another complaint is connecting a drainage hose. I agree that they did not leave much clearance for the attachment but I was able to attach a hose without problems. Now the bad news is I just read that Whirlpool is closing their dehumidifier factory (newspaper article). So if you are considering one you might want to grab it because they may be moving production off shore.
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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 06
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%20performance.pdf
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
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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, snipped-for-privacy@ece.villanova.edu wrote:

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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

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.
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Are you all distinguishing between an indoor dehumidifier and an A/C? An indoor dehumidifier provides *net heat* to the space while dehumidifying, and an A/C cools, while providing the same (I think)dehumidification.
I use both in my shop. Summer: A crappy Amana portable A/C, venting out of a hole in the wall, about 850 watts, and Winter: a brandX dehumidifier from Sam's/Costco, about 600 watts. Both produce prodigious amounts of water--the Amana, about 7,000 btu at a miserable 8.5 EER, cranks out about 5 gals/day, moderately humid weather.
I wonder if a 40 W system could do that.
An indoor dehumidifier is basically window A/C brought inside, and rigged in such a way that it doesn't freeze up. I've tried a regular window A/C as an indoor dehumidifer, and it worked, but froze. Also, A/C's cycle on temp, dehumidifiers cycle on, well, humidity. I have a broke dehumidifier, and I'm thinking of scavenging the humidity sensor and wiring it to the A/C--if that makes sense.
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Mr. P.V.\'d (formerly Droll Troll), Yonkers, NY
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On Jun 19, 9:48 pm, "Proctologically Violated"

My dehumidifier does "throw" heat while running. It is in my basement and there are no windows that would support an AC unit. I believe if I had to do it again, a window unit would be the best of both worlds. I would have to modify a casemount window to accomodate an AC unit.
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wrote:

My dehumidifier does "throw" heat while running. It is in my basement and there are no windows that would support an AC unit. I believe if I had to do it again, a window unit would be the best of both worlds. I would have to modify a casemount window to accomodate an AC unit. ========================= Or get a mini-split. They have them for as little as $500/9,000 BTU units, 10-11 EER. You'll need a guy w/ A/C gauges etc to connect/charge the condensor to the coil. Many of these mini's also have heatpump function.
Or the portable Amana's, etc, about $350 now. If demudification is your primary concern, you get moderate A/C for free! Beats heat in the summer.
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Mr. P.V.\'d (formerly Droll Troll), Yonkers, NY
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I got a 12,000 btu mini-split on eBay last summer and installed it myself. Many are precharged and as long as the line lengths work for you, can be installed easily. I'm very happy with it, and with careful positioning it does almost all of my 1st floor (I have a fairly open plan home).
I had to install custom line lengths, so I needed to cut and re-flare the line sets. I do have a vacuum pump and evacuated and leak-checked my lines, although the procedure that is outlined in the installation manual just used a timed blow-down based on the length of the line.
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Dennis


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Interesting. Where did you get your A/C tools from? Straightforward to use?
I thought the lines had to be hard brazed/soldered. Isn't flaring asking for trouble?
I would love to be able to do this myself. Really want to put the whole house on a bunch of minisplits. Got central A/C w/ essentially zero zoning, and it's killing me.
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Mr. P.V.\'d (formerly Droll Troll), Yonkers, NY
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entropic3.14decay@optonline2.718.net says...

Flared line sets are the norm for mini-splits, every one I looked at came that way. The higher priced ones may have dry-break quick connects, although the flared sets are also called 'quick connect' by many sellers so you really need to ask questions about ones you are interested in. Mine has been running a year and a half, fine so far, the brand name is Celiera.
I can't see any differences between the different units I was shopping for. The wall units are identical, they all use compressors from the same 1 or 2 manufacturers, the controls work the same, etc. The refrigerant is stored in the outdoor unit, and will purge and fill a specified maximum line length (usually 24 feet or so), if you need longer lines, you will need a pro to fill it and add more for any of the units.
You don't need any HVAC tools if you are willing to go with the standard installation method. You hook up the lines, look your line length up in a chart, set the valves in a certain sequence and finally purge the line-set and indoor unit by opening the shut off valve a quarter turn for X number of seconds. This is calculated to purge out the air, but shut off just as the refrigerant comes out.
Not a precise method in my mind (Hell, I'm not even sure if it's legal anymore, but that's the factory method) so I evacuated everything and filled into the evacuated system. I would suggest that is always a *better* way to go, since then you can be assured the flares are OK if they hold vacuum. I do have a lot of experience with flaring lines for a variety of exotic fluids so I am pretty confident with it. You could also add Voishan washers under the flares if you wanted, but soft copper seals quite well.
My vacuum pump is just a small Kinney lab pump, but HVAC pumps are readily available and are not too expensive. Many people use salvaged refigerator compressors for occasional HVAC use. The refrigerant on my unit uses the same fittings as R12, standard 1/4" flare, so it is easy to hook up. The new higher SEER may use a different fitting, they have a different refrigerant.
Dennis
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Sure, with dry outdoor air, but this version uses no electrical power:

And this version would only require sun, vs dry outdoor air:

Nick
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This one?

Where is the energy consumed? :-)
Nick
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The FSEC attic is only hot during the day, when it evaporates water from the dessicant.
Nick
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wrote:

My current dehumidifier is well over 20 years old - mabee even 30. The fan went bad a few years ago and I got one at a surplus shop for $5. I would never do without one here in Southern Ontario in the summer.
We use one in the office too, next to the copier, to prevent the paper from getting "soggy" and jamming all the time. Threw out a 30 year old one that was getting noisy again last fall, now I need to get another one.
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