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
http://search.sears.ca/sears/srch?se...se_n=1&se_p=15
lists 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

wrote:

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...

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.

...So while for much of the continent, the season for dehumidifying
is the summer, on the left coast it is the winter.

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

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.

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.

On the other hand, we may allow our rooms to cool below 65 degrees...

Good.

Any suggestions?

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.

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?

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

wrote:
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.

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 :-).


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
http://search.sears.ca/sears/srch?se...se_n=1&se_p=15
lists 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.

--
Joseph Meehan

Dia duit

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 .

Try Therma-Stor

Thanks for your comments, Nick!

wrote:
wrote:

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...

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.

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.

...So while for much of the continent, the season for dehumidifying
is the summer, on the left coast it is the winter.

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

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.


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.

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.

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.

On the other hand, we may allow our rooms to cool below 65 degrees...

Good.

Any suggestions?

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.

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.

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?

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.

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.

Nick

Thanks, Joseph ....

Joseph Meehan wrote:
wrote:


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.

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 :-).

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

Thanks, mR !

m Ransley wrote:

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.

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


What is the SQ ft of your house and normal high % humidity .

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

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

wrote:

Thanks for your comments, Nick!

You are welcome.

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...

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.

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?

No. That varies with temperature.

I also doubt the accuracy of the figures. Ave. Temp. of 50.5 F in December?
Nonsense, or a typo.

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.

...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.

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

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.

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

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.

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.

...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.

Sounds like you have a major indoor humidity source.

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.

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.

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.

That's backwards :-)

Any suggestions?

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.

Summertime is never an issue here. I'm afraid that the most
hygroscopic house materials are the books.

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

Don't want to store moisture in our books.

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

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.

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.

By "humidity ratio", do you mean "relative humidity"?

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

Nick

For 900 sq the Sears 70 pt would do you fine

wrote in message
...
wrote:

snip
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.

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.


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

daestrom wrote:

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.

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.

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.

Wrong. It adds 1.6 kWh.

Nick

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

wrote in message
...

Wrong. It adds 1.6 kWh.

Nick

Thanks again.

wrote:
wrote:

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...

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 40.5 F
(corrected figures)
.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.

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?

No. That varies with temperature.

The temperature does vary.

...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.

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

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.

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.

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

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.

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.

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.

That's backwards :-)

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.

Any suggestions?

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.

Summertime is never an issue here. I'm afraid that the most
hygroscopic house materials are the books.

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

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.

Don't want to store moisture in our books.

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

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


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.

Cold air tends to be drier than warm air. You have my numbers, which you
seem to have ignored.

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.

It isn't hard to make a hole in a window.

I hadn't thought of that.

You may already have an exhaust fan in a kitchen or bathroom.

Kitchen.


By "humidity ratio", do you mean "relative humidity"?

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

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.

--
Jonathan Berry

On Wed, 19 Oct 2005 19:18:52 -0400, "John P.. Bengi"
JBengispam@spam@yahoo,com wrote:

wrote in message
...

Wrong. It adds 1.6 kWh.

Nick


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


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

"wmbjk" wrote in message
...
On Wed, 19 Oct 2005 19:18:52 -0400, "John P.. Bengi"
JBengispam@spam@yahoo,com wrote:

wrote in message
...

Wrong. It adds 1.6 kWh.

Nick


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


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

In article ,
says...

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.

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

...So while for much of the continent, the season for dehumidifying
is the summer, on the left coast it is the winter.

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

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.

--
is Joshua Putnam
http://www.phred.org/~josh/
Updated Bicycle Touring Books List:
http://www.phred.org/~josh/bike/tourbooks.html

wrote in message
...
daestrom wrote:

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.

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.

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.

Wrong. It adds 1.6 kWh.


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

daestrom wrote:

Dehumidifiers produce heat...

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.

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.

Wrong. It adds 1.6 kWh.

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

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

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.

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

Nick

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

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.

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


Only for as long as it takes the water to evaporate again.
UNLESS you're clever enough to dump the condensate outside
the building envelope. At that point, whether you gain any
extra depends on whether it takes more energy to heat up
the condensate again, or to heat up the air-volume that you
have to acquire to replace it.

I see daestrom's point from a Physics point of view, but in
practicality I agree with Nick. With months of heating season ahead,
you have damp air in your house. What can happen to that air? It can
be ventilated, exhausted from the house (and, in most climates,
replaced by drier air) and the vapour energy is simply lost (to the
homeowner). The only way to keep the energy is to condense the vapour
inside the house, and the best place for the condensed vapour is down
the drain (or in houseplants), thanks to a dehumidifier. Not in your
books or insulation or constantly on your windowpanes.

--
Jonathan Berry

wrote in message
oups.com...
I see daestrom's point from a Physics point of view, but in
practicality I agree with Nick. With months of heating season ahead,
you have damp air in your house. What can happen to that air? It can
be ventilated, exhausted from the house (and, in most climates,
replaced by drier air) and the vapour energy is simply lost (to the
homeowner). The only way to keep the energy is to condense the vapour
inside the house, and the best place for the condensed vapour is down
the drain (or in houseplants), thanks to a dehumidifier. Not in your
books or insulation or constantly on your windowpanes.


The only problem with that here in NY is, we don't have a lot of 'damp air'
in the house in the winter time. Quite the opposite, because of low outside
temperatures, the house can be quite dry and we have to run a *humidifier*,
not a *dehumidifier*. Not for any sort of energy, but just for
comfort/health.

The only time we need to run a *dehumidifier* is in the basement area in the
summer time. These units cool the air to remove moisture, then re-heat the
air from the condenser section of the vapor-cycle. Net result is it warms
up the basement slightly.

But I guess I can see where in some climates, where the winter temperatures
don't get too low, the dampness can be a bother. But seems like if it gets
down to say 40F outside , then when you warm your home air up to 70F you've
got just the right humidity, not too damp at all.

daestrom

wrote in message
...
daestrom wrote:

Dehumidifiers produce heat...

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.

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.

Wrong. It adds 1.6 kWh.

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

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

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.

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


Yes, you're right I meant raising the sensible heat.

But if the basement or whereever has 100% RH at 50F, then your dehumidifier
is discharging it's heat at about 55F, not much use there. I have never
seen a dehumidifier that can extract moisture in a 50F basement and direct
the heat into a 70F house.

The only dehumidifiers I've seen take the air and cool it to remove
moisture, then warm the same air back again with the condenser coil of the
same vapor cycle. Sure, in 68F basement with 80% RH, you can warm the air
out of the dehumidifier to a higher temperature, but it's still in the
basement. In winter, when the basement is 50F, your dehumidifier will only
succeed in warming the basement air to 55F or so. Still not much use in
that.

You have a dehumidifier with separate evaporator and condenser coils so you
can place one in the basement and one in the living space? And able to work
well with a 30 F delta temperature? Not your 'average' dehumidifier.

daestrom

daestrom wrote:

wrote in message

...With months of heating season ahead, you have damp air in your house.

From human activities (2 gal/day), and a possible damp basement floor, which
can be arranged with a humidistat and a solenoid valve and a soaker hose :-)

What can happen to that air? It can be ventilated, exhausted from
the house (and, in most climates, replaced by drier air) and the vapour
energy is simply lost (to the homeowner). The only way to keep the energy
is to condense the vapour inside the house, and the best place for the
condensed vapour is down the drain...

Agreed. If it leaves the house at 40 F, there's another slight gain.

The only problem with that here in NY is, we don't have a lot of 'damp air'
in the house in the winter time. Quite the opposite, because of low outside
temperatures, the house can be quite dry and we have to run a *humidifier*,
not a *dehumidifier*. Not for any sort of energy, but just for comfort/health.

A need for winter humidification is a sign of an air-leaky house.

Nick

daestrom wrote:

...if the basement or whereever has 100% RH at 50F, then your dehumidifier
is discharging it's heat at about 55F, not much use there.

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

Not an air leaky house but just a large heated air differential. Many add heat
exchangers to increase the "leaky house"

Going from -30C to +21C via heating leaves very little moisture (rh) despite the
sweating and cooking people.


wrote in message
...
daestrom wrote:

wrote in message

...With months of heating season ahead, you have damp air in your house.

From human activities (2 gal/day), and a possible damp basement floor, which
can be arranged with a humidistat and a solenoid valve and a soaker hose :-)

What can happen to that air? It can be ventilated, exhausted from
the house (and, in most climates, replaced by drier air) and the vapour
energy is simply lost (to the homeowner). The only way to keep the energy
is to condense the vapour inside the house, and the best place for the
condensed vapour is down the drain...

Agreed. If it leaves the house at 40 F, there's another slight gain.

The only problem with that here in NY is, we don't have a lot of 'damp air'
in the house in the winter time. Quite the opposite, because of low outside
temperatures, the house can be quite dry and we have to run a *humidifier*,
not a *dehumidifier*. Not for any sort of energy, but just for
comfort/health.

A need for winter humidification is a sign of an air-leaky house.

Nick

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.

wrote in message
...
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

daestrom wrote:
wrote in message
oups.com...
I see daestrom's point from a Physics point of view, but in
practicality I agree with Nick. With months of heating season ahead,
you have damp air in your house. What can happen to that air? It can
be ventilated, exhausted from the house (and, in most climates,
replaced by drier air) and the vapour energy is simply lost (to the
homeowner). The only way to keep the energy is to condense the vapour
inside the house, and the best place for the condensed vapour is down
the drain (or in houseplants), thanks to a dehumidifier. Not in your
books or insulation or constantly on your windowpanes.


The only problem with that here in NY is, we don't have a lot of 'damp air'
in the house in the winter time. Quite the opposite, because of low outside
temperatures, the house can be quite dry and we have to run a *humidifier*,
not a *dehumidifier*. Not for any sort of energy, but just for
comfort/health.

See subject line, "Pacific Coastal Dehumidifier". Here in Canada, it
seems difficult to get a dehumidifier you could put in your living
space (all the ones I have seen are too loud, they might go in the
basement) because so much of Canada has a Continental climate not too
dissimilar from New York.

Some houses, such as my own, have humidity excess from late September
until June. Aside from the Pacific Coastal climate, those in other
areas could have the same challenge if their house is built tightly, as
Nick pointed out.

--
Jonathan Berry

wrote in message
...
daestrom wrote:

...if the basement or whereever has 100% RH at 50F, then your dehumidifier
is discharging it's heat at about 55F, not much use there.

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.


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

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.

"daestrom" wrote in message
...
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

daestrom wrote:

...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.

The outside half of a window AC might be a bit loud for putting in the
living space.

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

And these units aren't really meant to condition the cold side... below 55F.

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

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.

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

Besides, once you dry out the basement, you going to deliberately spray
water on the floor?

Maybe.

Like to see what that does for mold/mildew levels.

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.

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,

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.

A far more effective method would be to use a heat pump designed for the
purpose and extract heat from the ground directly.

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.

Avoids the mold/mildew...

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.

Only down side is total cost...

A pesky detail :-)

Nick

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_...s_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