Pacific Coastal Dehumidifier

The weather on the Pacific Coast from Northern California to British Columbia tends to be warm and dryish in the summer but cool and damp in the winter. Depending upon where you are, there may be no need for summer air conditioning / cooling. So while for much of the continent, the season for dehumidifying is the summer, on the left coast it is the winter.

Dehumidifiers produce heat, therefore their energy efficiency is important in continental applications. However, on the left coast, they are used mostly in the winter, so the heat they produce is mostly a slightly more expensive form of something you're going to do anyway: heat the air in the house.

On the other hand, we may allow our rooms to cool below 65 degrees. I know that I do. But as I discovered yesterday when reading the manual of a Classic ECD15E Dehumidifier purchased from Home Hardware, operation of a dehumidifier at below 65 degrees is frowned upon, for two reasons: efficiency goes in the sink (so to speak), and the coils can freeze up, causing waste and damage. So much for the idea of moving the unit from room to room, leaving it in an unoccupied room. We could have lived with leaving it in the living room and allowing the dry air to seep into less used corners of the house, but the fan of the unit is too loud. Unfortunately, loud fans seem to be a fact of life in Canadian appliances (gas fireplaces, fume hoods...).

So I took the unit back, and Home Hardware kindly refunded the purchase price of $cdn190 plus taxes, which I thought rather a lot considering its simplicity.

For west coast uses, energy efficiency isn't so important, but the ability to operate (or at least the ability not to break down) at 65 degrees or less IS important. Those are two big differences from the dehumidifiers used in "continental" climates.

Any suggestions? Canadian Tire has a line of six dehumidifiers, all made by "Simplicity" (= Danby). I went out to Canadian Tire here, and found that they did have a couple of these in stock, but they were all in crates, no display. And no Efficiency Ratings for any of them. That was at the beginning of the search, so perhaps I was picky. Since then I've checked Future Shop (none), London Drugs ( none), Home Hardware (just the one mentioned, and a larger model of the same), Zellers, Superstore (their online catalogues don't list anything). Sears

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no less than 15 units, but after looking at a couple, I see no sign of low temperature operation, no mention of noise levels.

Going outside Canada, I saw a DeLonghi dehumidifier advertised as offering operation down to 44 F. Not sure how I'd get one here.

So, does anybody manufacture a "Left Coast Friendly" dehumidifier, and how can I get one in Canada? Our house is only 900 square feet, so the smallest size will probably be appropriate.

Finally, wouldn't a dehumidifier be more efficient if it took the warm moist air in at ceiling level, then expelled warm dry air at floor level? That would recirculate the air for those of us with 8- foot ceilings and thus no ceiling fans. Yet consumer dehumidifiers are universally designed to sit on the floor. I'm not sure what I'm suggesting, maybe a permanent installation in one room, or maybe something that can be moved around like a pole lamp.

-- Jonathan Berry

Reply to
jberry
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Maybe not. NREL says Seattle has these average temps and humidity ratios:

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

40.1 43.5 45.6 49.2 55.1 60.9 65.2 65.5 60.6 52.8 45.3 50.5 F

..0042 .0045 .0046 .0051 .0061 .0072 .0082 .0085 .0078 .0065 .0051 .0044

The humidity ratio w is the number of pounds of water vapor per pound of dry air. It does not depend on the air temperature, and it doesn't change much in 24 hours. The relative humidity is the number of pounds of water vapor per pound of air divided by the maximum number of pounds of water vapor the air can hold (at 100% RH) at a certain temperature.

That could be true in a Canadian airtight house with humidity sources, unlike air-leaky US houses with energy-wasting winter humidifiers...

It's cheaper than electric resistance heat, with a COP of about 1.6. You can measure this with a Kill-a-Watt meter and a measuring cup.

Good.

Turn on a small exhaust fan with a humidistat when the indoor RH rises to

60%. In January, w = 0.0042 makes Pa = 29.921/(1+0.62198/w) = 0.201 "Hg. Indoor air at 60% RH and absolute temp T (R) has Pi = 0.6e^(17.863-9621/T), approximately, and Pa = Pi makes T = 507.5 R or 507.5-460 = 47.5 F, so you can dehumidify the house with an exhaust fan as long as the indoor temp is at least 47.5 F. If you want to save more energy, take advantage of weather fluctuations and hygroscopic house materials and do this less often, only when the outdoor air is warmer and drier than average (during the day) in wintertime and cooler and drier (at night) in summertime.

Maybe not. Diffusion and convection make the water vapor pressure and the humidity ratio of the air near the ceiling and floor about the same, even though humid air rises.

Nick

Reply to
nicksanspam

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 .

Reply to
m Ransley

Try Therma-Stor

Reply to
Stretch

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 :-).

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lists no less than 15 units, but after looking at a couple, I see no

Reply to
Joseph Meehan

I'm not sure how the absolute figures given above relate to the experience that everyone who lives here has. Wouldn't RH be more pertinent? I also doubt the accuracy of the figures. Ave. Temp. of

50.5 F in December? Nonsense, or a typo. Our own experience here, and I don't think Seattle is too much different (although Seattle is definitely wetter) is that it does not rain in August, and if it does rain, the ground can be "bone dry" again in half an hour. In November, on the other hand, it seems to rain constantly; your lawn will be a quagmire. Water tables rise, and the moisture evaporates through your basement walls into your living space.

I'd suggest that the moisture figures above reflect a) the fact that warmer air is able to carry more water vapour and perhaps b) some sort of filtering out of the effect of rain.

Airtight houses in Canada tend to be where the climate is severe. The ideal place is Saskatchewan, which has hot summers and severe winters with lots of sunny days. Airtight, passive solar, summer-shading overhangs ... all work out well in Saskatchewan. There they have a "continental climate" which would not likely need dehumidification in winter.

Here in coastal British Columbia, construction tends to be more leaky. And the case in consideration, our house, is a leaky house built in the

1930s. This thread is the result of an Energuide energy audit, which resulted in the consultant telling us that we should make the house more airtight, but that BEFORE we did that, we had to deal with the humidity issue.

That's reassuring. We're also looking forward to the subjective feeling of warmth in dry air at a temperature where we would feel cold in damp air.

Summertime is never an issue here. I'm afraid that the most hygroscopic house materials are the books. Don't want to store moisture in our books. So it looks like you also prefer exhaust fans to dehumidifiers. My concern is that the warm damp air gets replaced by cold damp air from the basement or outside. I'd really like to give dehumidification a chance before making another hole in the wall.

By "humidity ratio", do you mean "relative humidity"? So, let's say that the air at 70F and 70% humidity at ceiling level, but 65F and 70% humidity at floor level. Something like that? Then I submit that this could still be an advantage because of the dehumidifier's greater efficiency at 70F than at 65F.

Reply to
jberry

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.

Reply to
jberry

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.

Reply to
jberry

Thanks, Stretch.

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(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.

Reply to
jberry

You are welcome.

No. That varies with temperature.

Oops. A typo. Shoulda been 40.5, with 35.8 and 45.1 average daily min and max. I rechecked the rest of the numbers, which look OK.

Maybe that's where your water vapor is coming from. A 1930s house with no vapor barrier under the basement floor?

Dunno about rain. Warmer air can carry more water vapour.

Airtight houses need dehumidification in wintertime because they contain humidity sources, people breathing and showering and washing floors and cooking and so on, as well as damp basements. A perfectly airtight house would let the indoor RH rise until condensation happens on the indoor surface of windows.

Sounds like you have a major indoor humidity source.

That's backwards :-)

Also concrete, wood, paper, fabric, and so on.

The RH might range from 30 to 60% with no damage.

Cold air tends to be drier than warm air. You have my numbers, which you seem to have ignored. It isn't hard to make a hole in a window. You may already have an exhaust fan in a kitchen or bathroom.

No. I already explained the difference. You seem to have ignored that too :-)

Nick

Reply to
nicksanspam

For 900 sq the Sears 70 pt would do you fine

Reply to
m Ransley

The temperature does vary.

The water vapour could be coming from the basement, yes, it is likely. There is no stairway for the moisture to come up to the main floor, just the furnace and a few small holes for plumbing. Yet rise it does.

Is it? In places like Saskatchewan, they make a joke about the temp being minus 40 but tolerable because "it's a dry cold". You can be sure that when those same people retire to British Columbia, they often feel (subjectively) colder even though the temperatures are oh 40 C warmer, because of the dampness of the cold. And the most harrowing tales of winter misery are not from the Yukon, but from houses in damp England.

Books are made of paper. If the moisture condenses, it can easily evaporate from wood or fabric, but not so easily from books in bookcases against a wall.

That shows that the RH is frequently above 60% because the books in my office, next to the wall, do get a touch damp.

I questioned their applicability. I remember about 25 years ago I wanted to get an old house in Ottawa insulated. The main choices at the time were blown in cellulose and urea formaldehyde. I was dubious about the UF, so I asked the contractor to provide "proof" that it was OK. Surprisingly, they provided lab studies which "proved" that UF was OK. I looked at the figures and the methodology, and concluded that in the real world there was no way that UF foam could be blown the way it was in the lab, so I went with cellulose. A couple of months later, the issue blew up and I luckily didn't have to take the contractor to court or demolish the house etc.

So I'm not sure what your numbers mean in this context. It can rain zero days in August, and 29 days in November, yet August is considerably damper than November. I can only think that those figures somehow have the rain column shunted off into another category. Also, the temperature inside the house does vary. In summer, we allow the temp inside the house to go up to 76 or even 80. It is still comfortable; if not, we can go outside under the grape arbour. At other times we might let the temperature fall to 65 or even 62 and put on a sweater. Those are the times when the vapour might condense out, and those are the times we might need the dehumidifier.

I hadn't thought of that.

Kitchen.

Ooops, sorry, I have a selective memory. Sometimes it doesn't cotton on to terminology. Maybe I'll remember now.

But this is interesting ... the air at the top of the column might be

70F, with an RH of 50%, but at the bottom of the column 65F with the same "humidity ratio" and therefore a higher RH. The warmer air might not activate the unit's humidistat. That is consistent with the observation that in the morning when we wake up, most of the condensation is at the bottom of the window; the top may be clear. It might also explain how the basement is a source of humidity to the main part of the house: warm damp air rises through cracks, but never has a chance to settle back down into the basement. And finally, it makes me think that this old house might be more air-tight than I thought it was. The wall construction is peculiar, as it includes 1" thick horizontal planking. Maybe that traps a bit more of the moisture which would otherwise escape.

More dehumidifier investigation: Local stores (to Nanaimo, BC): Zellers and The Bay don't sell them. Wal*Mart has a Fedders unit whose model number (D4989M) does not match any specs on the Internet. The closest source for Bionaire in Canada is a dealer in London, Ontario (over 2,000 miles away). No local refrigeration outlet has a dehumidifier in stock, though one said he could order a Friederichs D30 unit for $cdn488. As reported earlier, there seem to be at least three manufacturers (Bionaire, Soleus, Surround) who produce a small dehumidifier with a noise level around 40 dBA and some sort of anti-frost protection so that the unit can be allowed to operate at temps of 65 or lower. The latter two seem not to be available in Canada.

Reply to
jberry

Wrong. It adds 1.6 kWh.

Nick

Reply to
nicksanspam

Are you going to explain where you get the 0.6 kWh free, or are you just trolling again?

Reply to
John P.. Bengi

Reply to
John P.. Bengi

The COP doesn't matter as far as adding heat to the house goes. A kwh of electric to run a dehumidifier adds a kwh of heat to the building, just like a kwh of electricity through a resistance heater.

The only difference is a kwh of electric through a dehumidifier not only adds a kwh of heat to the building, it removes some amount of moisture from the air.

daestrom

Reply to
daestrom

Gymmy Bob, check the cross-postings, you're getting your nyms and groups confused again. You haven't been Bengi in the energy groups for months now. You're Solar Flare here now, remember?

Wayne

Reply to
wmbjk

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.

Reply to
Joshua Putnam

BULL.

Care to explain where the extra 0.6 kwh came from??

Granted the vaporization energy removed from the moisture gets dumped into the room as latent heat, but that energy was always there, you've just used some entropy from the electricity to change the heat of vaporization to latent heat.

One kwh of energy into a dehumidifier means one kwh of energy added to the house. Period. No miracle COP will add more energy to the house.

daestrom

Reply to
daestrom

Sure. Evaporating water takes energy. Condensing it releases energy.

I'd call that sensible heat. It makes the house warmer :-)

Nick

Reply to
nicksanspam

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