Pacific Coastal Dehumidifier

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I suggested moving some 55 F 100% RH air up from the basement floor to the living space where the dehumidifier lives. Harvard Physicist Bill Shurcliff suggests putting a window AC in a basement stairwell with the warm side in the living space to air condition the basement and heat the house in wintertime.
Nick
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Quite the opposite. People want their basements warmer to get usable space. The heat is hard to force into the lower cavities as it keeps coming back up in the colder climates.
Simple top to bottom or bottom to top ventilation works wonders. Houses in extreme climates should all have a top to bottom ventilation system.

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The outside half of a window AC might be a bit loud for putting in the living space. And these units aren't really meant to condition the cold side (normally the room, but in this case the basement) down below 55F. But I suppose you might try reducing the air flow so the coil runs cooler. If there's a lot of moisture, one might have problems with freeze-up though.
Besides, once you dry out the basement, you going to deliberately spray water on the floor? Like to see what that does for mold/mildew levels. Your scheme is just using heat at ~50F on the floor slab/ground to evaporate water, then using a dehumidifer to condense the water putting the heat into the living space. A far more effective method would be to use a heat pump designed for the purpose and extract heat from the ground directly. Avoids the mold/mildew, higher COP, and can be designed to supply a lot more heat. Only down side is total cost (but I'm not sure it cost more $/BTU delivered).
If your basement is damp in the winter time, *thats* a sign of a poorly waterproofed/sealed basement foundation/floor. The only time you should have trouble with damp basements is summer, when the warm moist air from outside finds its way into the much cooler basement (RH goes up in the air as its cooled, making things 'feel' damp/clammy), -or- when the foundation is below the water table and not properly sealed. How does a 50F 100%RH weather outside make a basement 'damp', unless the basement is even cooler??
Those in Pacific northwest obviously have a different issue, but for most of us the dehumidifer gets shut off in the winter as there isn't enough humidity in the air to condense (unless your dehumidifier works down in the 30F range)
daestrom
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Despite all the silly schemes and logic the simple answer for 99% of the people is to increase their air circulation.
This gets the moisture throughout the house where it may be desired and heat the basement more so the rH drops.
Moisture in the basement is only a sign of air stratification and does not indicate leaks. Only higher rH due to cooler air and condensation.

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Agreed. Maybe it needs a sound enclosure with baffled airflow paths.

True, altho some people use them for walk-in coolers, with freezestats.

We might turn off the compressor with a freezestat on the cold side.

Maybe.
Maybe nothing, with a humidistat and a soaker hose and a solenoid valve from an old washing machine to keep the RH near the floor 60%. Would that work? Pb = 0.6e^(17.861-9621/(460+50)) = 0.220 "Hg, so wb = 0.62198/(29.921/Pb-1) = 0.00461. Removing all that water makes 4.61 Btu per pound of air. Heating a pound of 50 F air to 65 F takes 0.24(65-50) = 3.6. Hmmm. Maybe we need an air-air heat exchanger. A natural molecular one, based on warm air bouyancy? Or a 2'x2'x8' counterflow closet with lots of vertical layers of plastic film? We might convert all the latent heat with about 5340/4.61/0.075/60 = 257 cfm.

We can also convert latent heat from people and their activities, about 2 gallons per day for an average family, Andersen says. And latent heat from a greenhouse or plants in the sun. Plants in the sun can evaporate 1 lb per day per square foot of floorspace, and moist air is a great way to move heat out of a greenhouse without much airflow.

I just bought a $69 10.2 EER 5340 Btu/h Daewoo AC. Restricting the cold side to lower the temp does not seem to change the COP. Restricting hot airflow to make it 110 F dropped it to 2... 3 tons of Daewoos would cost $69x36000/5340 = $465.

What mold and mildew? We might AC a non-people space, eg a moldy coldframe or mushroom house, with compost heat. Dry compost materials have the same heat value as wood, about 10K Btu/lb. With proper care in a closed vessel, they can lose 15% per day by weight. Horses or cows might help. With an AC, we don't have to breathe the same air.

A pesky detail :-)
Nick
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I decided to buy locally, so no Bionaire or Surround unit. I got in touch with somebody who (used to) sell the Soleus. Although it earns excellent reviews, he said that he got a lot of returns because the unit didn't work. Not good when you have to pay shipping; even worse when it is trans-border; the differential between the cost and difficulty of domestic versus international shipping seems far greater than it was before NAFTA. *Another* downside of that agreement.
I bought the Fedders A7DH45B2A Dehumidifier, reviews at
http://www.dealtime.com/xPR-Fedders_Fedders_Dehumidifier
for $cdn 250 from Home Depot. The reviewers differ as to whether it is noisy or quiet; expectations must play a role. It is noisy, but not in an annoying way. If it comes on in a room 15 feet away with the door closed, I don't wake up from my sleep because of it. Sometimes it does peculiar things, like not turning on or turning off when the numbers say it should. Once I found it in high fan mode with the condensor turned off. In each case I was able to fix the problem by unplugging the unit. So the claim that it will remember its settings after a power outage is false. The fact that it resets by unplugging is a boon -- how else would you fix it if it got stuck in some strange mode?
It rolls and handles well. As it is plasticky, it is also light enough to carry (empty the reservoir first). Con: Made in China. Con: costs a lot more in Canada than in USA. Con: Cycles on and off ( 2 minutes?) frequently when near equilibrium point. Pro: numbers nice; Con: numbers (relative humidity) aren't accurate. Pro: pressing a single button will pause the unit for an hour when you need quiet.
Compared to the Home Hardware Classic which I returned earlier, the Fedders has the crucial advantage of "low temperature" (65 degrees F or below) operation. The Fedders is less noisy, reservoir removes from the front, removes more moisture per unit time, is Energy starred. The only advantage of the Classic is the metal chassis, though that makes it heavier.
I'm not going to pretend that I'm 100% happy with this purchase, but life is a series of compromises. The condensation on our single pane windows is considerably reduced. Now that we have the interior moisture under control, as specified by the EnerPlan inspector, it's time to move on to calling for quotes on the windows. I've pretty much decided to pay a bit extra and get sealed 2-ply low-e (high sunlight transmission version), argon-filled units. Of the 15 window openings in the house, only about 3 need to be operable (open-able). So on the inoperable windows, that leaves us with 5 options: --reglaze (replace glass only in existing sash) --retrofit (new sash unit in existing frame) --replace (rip out old frames entirely) --exterior storm (don't remove old glazing at all) --interior storm.
The old wood frames are mostly in pretty good shape. Inside, there is lots of room and various surfaces where an interior storm could find purchase, a good seal could be made. I'm inclined to go that route. The energy inspector warned me that the unit closer to the living space should always be more airtight than the unit next to the great outdoors, otherwise you'll have condensation building up in between. The current windows have been carefully "sealed" with 7 decades of paint, but if need be I could drill a hole at the bottom of the sash and insert a small bit of medical tubing to allow access of dry exterior air and, although it should never come to that, drain off any condensation.
--
Jonathan Berry



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snipped-for-privacy@ece.villanova.edu says...

RH is a more relevant humidity than absolute when you're talking about moisture damage, condensation, etc.

I can't think of anyone I know in the Seattle area who uses a humidifier in winter. I know quite a few who de-humidify in winter, since that's our humid season. Using a humidifier in winter here seems like an invitation to mold and rot.
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snipped-for-privacy@phred.org is Joshua Putnam
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snipped-for-privacy@islandnet.com wrote:

Better quality dehumidifiers can handle the lower temps, but they will cost a bit more. Look for units that are designed for basement use (even though it is not likely you have a basement :-).

http://search.sears.ca/sears/srch?se_l=e&se_q humidifier&se_cat=air&se_cmd=searchWithLinguistics&se_res=QIR_ShopOnline&cqon=true&se_n=1&se_p
--
Joseph Meehan

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Sears has a model that runs to 45f, it may also be one of the most efficient made. Consumer reports rated them and their low temp freeze ups.
A free link to consumer reports for 30 days. ConsumerReports.org/cr/free7 I would set it in a central location with a drain hose attached, keeping it in a room wont circulate air as much. My sears has a 6 hr on 6 hr off run ntimer it could be set to enguage when you sleep. Yes they are noisy.
Removing humidity is not like heating or cooling you dont need it at the ceiling.
Get an "Energy Star" rated unit on Sears an other it is imprinted on the front permantly. New Energy star units are much more efficient than old units and produce less heat apx 2/3 more efficient and 2/3rds less heat.
The Sears 45f model is the large unit apx 175-225 but you are dehumidifying a house not a basement so for say over 1000sq ft it might be adequate.
What is the SQ ft of your house and normal high % humidity .
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Try Therma-Stor
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Thanks, Stretch.
http://www.thermastor.com/prod_100v.htm
(a dehumidifier and air cleaner which attaches to the ductwork and pressurizes the house, drawing controlled fresh air from outside)
is pretty cool. Pardon the pun. However, I'd like to give the cheaper, low-tech solutions a chance before making what is undoubtedly a major investment.
--
Jonathan Berry



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Thanks, mR !
m Ransley wrote:

Sleep ... noisy is a combination that doesn't work for me! But I am finding some quiet ones (see other posting).

House is still 900 SQ ft (7200 cu ft?) and the humidity is such that in early October we wake up to windows close to totally covered with condensation (furnace not yet on for the season). Sorry, I don't have a RH value, just know that it is higher than it ought to be.
--
Jonathan Berry



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Thanks, Joseph ....
Joseph Meehan wrote:

Basement dehumidifiers also tend to be noisier. With further research, I've nailed down some small dehumidifiers which are both quiet and operate at low temp. For example the Soleus Air CFM-25 (41 decibels, 36 F), available through amazon.com, but not amazon.ca. Bionaire Dehumidifier BDQ24-UC Quiet Tech is quiet, but not sure about low temp. It does have auto defrost. Surround Air 400 (39 decibels, auto frost sensor). Haven't found a local source for the Bionaire, even though Bionaire started in Canada. The Surround is available mail-order from several distributors in the USA. Again, no Canadian source yet.
So, they're out there, but not sure if they're available locally. If I were confident about the quality and suitability of a unit, I might order it from away, but I'd prefer to buy locally.
We do have a basement, but we don't want to have to put the dehumidifier there.
--
Jonathan Berry



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