Re: Frugal Dehumidifier - any good models widely available?

 



How about a Crawlspace Smart Vent?

http://www.smartvent.net

They cost $365, but they only use 40 watts when moving 290 cfm of air
out of a basement when the absolute moisture content of basement air
is greater than the absolute moisture content of outdoor air.

To also heat (cool) a house in a cool (warm) season, we might power up
the Smart Vent with a differential thermostat only when outdoor air is
warmer (cooler) than house air.

Nick

 



...

Does that mean when the absolute moisture content is the same (high or low)
it does noething?  Seems like it would have limited value in a naturally
humid region whee you want to make it lower.

 



The technical description on the crawlspace web page says they evacuate
crawlspace air when its RH is more than 35% and the absolute moisture
content of the outdoor air is lower than that of the crawlspace air.
They also evacuate crawlspace air when the crawlspace RH is less than
25% and outdoor air has 20% more absolute moisture. They say adding
humidity to a crawlspace is sometimes useful to keep it from drying out
to the point that hardwood floors buckle.


Yes. This might work well in a climate with some humidity variability
and with a fairly airtight crawlspace and some building materials that
can store moisture. It would work better in Chattanooga (wmin = 0.0036
in January) than Key West (wmin = 0.0100 in January.)


Yes. It only works on dryish days. There's a nice graph of crawlspace
humidity over time on the web site.

Nick

 


Thermastor makes the most efficient dehumidifier, according to Energy Star.
Costs a lot but can pay for itself in energy savings.  When I bought mine,
it was twice as efficient as the models sold at Sears.  I use it to dry out
my swamp of a basement.  It's somewhat noisy, but apart from that I have no
complaints.

http://www.thermastor.com/Santa-Fe/

The powered vent that Nick recommends would be a lot cheaper to buy and to
run, assuming it can be used in your application.

--
Bill McFadden     billmc@agora.rdrop.com    http://www.rdrop.com/users/billmc
CAUTION: Don't look into laser beam with remaining eye.

 

On 23 Apr 2007 14:15:55 -0400, nicksanspam@ece.villanova.edu wrote:


But that isn't what he asked about.  If he has a serious humidity
problem as I did then venting won't do a thing.  I tried (for about
$100 for a vent fan that fit in place of a concrete-block-sized vent).

Last year when I turned my vacation home into my residence and moved a
lot of possessions into my basement, I bought this dehumidifier:

http://www.samsclub.com/shopping/navigate.do?catgS5&item&6795&prDeTab=2#A

Which is this unit, private labeled for Sam's I think:

http://products.geappliances.com/ApplProducts/Dispatcher?REQUEST=SPECPAGE&SKU=AHG40LJ&SITEID=GEA&TABID=2

Same specs, same control panel, same looks.

Later I connected a watt-hour meter to the unit.  With the humidistat
set for 50% RH, from the period from 11/04/06 til today, the unit has
consumed 346 KWH or 2.03 per day.  At my power rate that's 13 cents a
day, $3.95 per month.

My basement is quite moist - green mold grew everywhere - but quite
cool, never going above 60 deg even in the summer.  That, of course
has a very favorable impact on the cost of operating this unit.

The way to evaluate the efficiency of a dehumidifier is its rating in
pints removed per KWH consumed.  Using the spec sheet of 580 watts
draw and 40 pints/day, that works out to 2.9 Pts/KWH.

It turns out that this is worst-case, for I just checked my unit with
a Kill-A-Watt and measured 450 watts.  That makes the Pts/KWH a much
better 3.7.  That compares nicely with the 5.3 that the Santa Fe unit
that Bill posted about in this thread.  The GE is far cheaper (list
price is $189).  At the energy consumption rate that mine is
exhibiting I could never save enough energy to pay the cost difference
for the Santa Fe.

One other thing to note.  For low temperature and/or very low humidity
operations, your dehumidifier must operate in the freezing mode.  That
is, the evaporator must get cold enough to form frost to condense
sufficient moisture to achieve a low humidity and the unit must have a
good auto-defrost cycle.   The GE does both.

For higher temperature operation and moderate humidity reduction, a
modified window AC works great.  The modification involves stopping up
the passage from the evaporator to the condenser that lets the
condensate be slung upon the condenser and evaporated.  Block the tube
and drill a hole in the bottom to allow the condensate to drain out.

At under a hundred bux for a 5KBTU window unit, that's a heck of a
good deal.  Just sit it in the floor over a drain or bucket and turn
it on.  If the room is small enough that the humidity is reduced
rapidly then you might need an external humidistat.

I used one like that in the upstairs part of my home for several
years.  I haven't measured the efficiency in terms of Pts/KWH but I
know that my power bill is about the same so the AC can't be a big
power hog.

John
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
All great things are simple and many can be expressed in single words:
Freedom, Justice, Honor, Duty, Mercy, Hope.  -Churchill