Re: Dehumidifying house in Summer

[Guest guest]

depends on the size of your house and the weather conditions outside. you might

want to get an extra one for inside of the house if you see the humidity creep

up. they are loud (at least my units are obnoxious). be sure to clean the

drainage bucket often as I see something black which could be from the motor but

I am not taking any chances. I also let the bucket dry out in the sun for

awhile. I hope this helps.

barb1283 <barb1283@...> wrote: I have one

dehumidifier running constantly in basement and one on

first floor running constantly just to keep humidity below 50%. It

seems weird to have TWO dehumidifiers running constantly just to keep

humidity below 50%. It's only the beginning of summer. They are both

Whirlpools and I bought sizes stated as appropriate for house size.

I'm trying to decide whether to get an 'inline' dehumidifier, to put

in ductwork like Therma Stor. Down side is that I hope to move in a

year or so and isn't as easy to move with, as I would have to take it

out of system and patch up holes in ductwork, etc.

Does anyone use a stand alone that is powerful enough to keep humidity

low without running CONSTANTLY to just keep it barely below 50%? It

makes me think when it gets humid out in July and August it will not

be able to keep up.

---------------------------------

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[Guest guest]

Barb,

You always have such good questions! And this is a doozy.

Dehumidification and drying are complex topics derived from the

science of Psychrometry. Not " psycho, " but " psychro. " It is a COMPLEX

topic because there are several variables that must be kept in

balance and they don't change in a simple linear manner. I'm far from

an expert here but I can say that some of the most heated debates

I've witnessed in the industry are over this topic.

What I can say is that under some combinations of temp, RH (relative

humidity) and SH (specific humidity) you could have 100 dehumidifiers

in your house and they would do no better than the 2 you already

have. They might not even be as effective as opening the windows - IF

the outside air is dryer than inside. (Warning: You can't just

determine " drier air " with a simple comparison of the relative

humidity of inside to outside. It is " relative " rather than

" specific " for a reason: Temperature. 30% RH at one temperature will

be 80% at another. You have to compare " specific humidity " ).

Each of the 3 basic types of technology for dehumidifiers all work

within fairly limited ranges of humidity and temperature. As the air

gets dryer and at different temperatures the conventional

dehumidifier (refrigerant, which is what you have) just can't remove

any more moisture from the air no matter how many you have running. A

different type, called a low-grain refrigerant dehumidifier is

needed. To get it even drier you need a dessicant.

As an example of the complexity, the newly released ANSI/IICRC S500

standard for water damage restoration has over 10% of its entire 370+

pages just on these topics. And it assumes you already have a basic

knowledge.

So before you invest in any more or different types, find a

professional who does not sell equipment. They can give you the best

guidance. As an alternative, do some Google research using the

vocabulary I've used. Most of the hits are for equipment but some

have excellent basic information. Be sure to Google " psychrometric

chart " to begin to appreciate all this.

That said, this knowledge in the hands of competent, trained

professionals using the proper equipment quickly enough can remove

water from the air, buildings and contents to stop water damage and

prevent mold growth.

Carl Grimes

Healthy Habitats LLC

-----

> I have one dehumidifier running constantly in basement and one on

> first floor running constantly just to keep humidity below 50%. It

> seems weird to have TWO dehumidifiers running constantly just to keep

> humidity below 50%. It's only the beginning of summer. They are both

> Whirlpools and I bought sizes stated as appropriate for house size.

>

> I'm trying to decide whether to get an 'inline' dehumidifier, to put

> in ductwork like Therma Stor. Down side is that I hope to move in a

> year or so and isn't as easy to move with, as I would have to take it

> out of system and patch up holes in ductwork, etc.

>

> Does anyone use a stand alone that is powerful enough to keep humidity

> low without running CONSTANTLY to just keep it barely below 50%? It

> makes me think when it gets humid out in July and August it will not

> be able to keep up.

>

[Guest guest]

Hi Carl,

Your response sheds a lot of light on problem! I tune into the

weather channel daily to see what humidity is outside. If it is 50%

or below I open my fresh air intake for the day thinking I'm

bringing in dry, fresh air, but humidity goes up anyway, and I have

to run dehumidifiers all day anyway. You are explaining reason is

that when air comes in and mixes with cooler air inside, it becomes

more humid than it was outside.

One really needs to take a course in keeping a home healthy!! It

isn't so simple.

The air in my house all winter long is so nice and fresh. I have

the fresh air intake open all winter long and cold dry air comes in,

mixes with inside air before it reaches furance, gets heated by

furnace and then is distributed through rest of the house. House

smells as fresh as outdoors all winter long. All summer though I

have stuffy house, struggling to keep humidity down even though

weather channel says it's beautiful, sunny and humidity 50% or less.

So if I want that outside 45-50% humid air inside, I have to let

inside temperature be the same as outside basically (or higher), but

there isn't enough air circulation inside to feel as nice as

outdoor. I have to get some fans going, and dust really well

first!!! Ceiling fans would be great but I'm not going to make

those changes in a house I plan to leave in the not too distant

future. Thanks!

--- In , " Carl E. Grimes " <grimes@...>

wrote:

>

> Barb,

>

> You always have such good questions! And this is a doozy.

> Dehumidification and drying are complex topics derived from the

> science of Psychrometry. Not " psycho, " but " psychro. " It is a

COMPLEX

> topic because there are several variables that must be kept in

> balance and they don't change in a simple linear manner. I'm far

from

> an expert here but I can say that some of the most heated debates

> I've witnessed in the industry are over this topic.

[Guest guest]

Barb,

Not only do you ask good questions, but you understand quickly.

Therefore, you get the next lesson in humidity.

When the pros determine whether to open windows or which

dehumidifiers to use to dry wet buildings they base it on Specific

Humidity, not Relative Humidity. Specific Humidity is based on weight

of the water compared to weight of air instead of a comparision by

percentage. Sounds weird, I know, but it works great.

Specific humidity is measured in grains per pound (gpp) of dry air.

For example, an RH of 50% will have 46 ggp at 65 degrees but 124 ggp

at 95 degrees - nearly 3 times as much water! If it is 95 outside and

65 inside, then opening your windows would increase the water in the

air in your house. In fact, it might make it rain inside your house

because 124 ggp at 65 degress is above In fact, it would raise the RH

inside to 100 percent at 74 degrees. At 65 degrees it would probably

be raining. Ouch!

Think it's impossible to rain inside a building? Maybe it won't rain

in the living quarters but it certainly does in a cool crawlspace

during high humidity.

An you thought mold was complicated.

Carl Grimes

Healthy Habitats LLC

-----

> Hi Carl,

> Your response sheds a lot of light on problem! I tune into the

> weather channel daily to see what humidity is outside. If it is 50%

> or below I open my fresh air intake for the day thinking I'm bringing

> in dry, fresh air, but humidity goes up anyway, and I have to run

> dehumidifiers all day anyway. You are explaining reason is that when

> air comes in and mixes with cooler air inside, it becomes more humid

> than it was outside. One really needs to take a course in keeping a

> home healthy!! It isn't so simple. The air in my house all winter

> long is so nice and fresh. I have the fresh air intake open all

> winter long and cold dry air comes in, mixes with inside air before it

> reaches furance, gets heated by furnace and then is distributed

> through rest of the house. House smells as fresh as outdoors all

> winter long. All summer though I have stuffy house, struggling to

> keep humidity down even though weather channel says it's beautiful,

> sunny and humidity 50% or less. So if I want that outside 45-50% humid

> air inside, I have to let inside temperature be the same as outside

> basically (or higher), but there isn't enough air circulation inside

> to feel as nice as outdoor. I have to get some fans going, and dust

> really well first!!! Ceiling fans would be great but I'm not going to

> make those changes in a house I plan to leave in the not too distant

> future. Thanks!

>

> > > Barb, > > You always have such good questions! And this is

> a doozy. > Dehumidification and drying are complex topics derived from

> the > science of Psychrometry. Not " psycho, " but " psychro. " It is a

> COMPLEX > topic because there are several variables that must be kept

> in > balance and they don't change in a simple linear manner. I'm far

> from > an expert here but I can say that some of the most heated

> debates > I've witnessed in the industry are over this topic.

>

>

>

>

>

>

>

>

[Guest guest]

OK, now ya got me listening in class...

Sooooo, instead of using my cheapo RH meters (I am pretty sure that is what

they are measuring - indoor/outdoor temp and indoor humidity -- darn things

can't keep time) -- how do I track SH??

Maybe you said this in an earlier formula/class??? Can we try it again for us

not so fast thinkers?

I've got two crappy dehumidifiers -- one freezes over often and the other

seems not wanting to shut off -- run and runs and runs (but it doesn't freeze).

Both are older Gibson models.

Thanks much.

" Carl E. Grimes " <grimes@...> wrote:

Barb,

Not only do you ask good questions, but you understand quickly.

Therefore, you get the next lesson in humidity.

When the pros determine whether to open windows or which

dehumidifiers to use to dry wet buildings they base it on Specific

Humidity, not Relative Humidity. Specific Humidity is based on weight

of the water compared to weight of air instead of a comparision by

percentage. Sounds weird, I know, but it works great.

Specific humidity is measured in grains per pound (gpp) of dry air.

For example, an RH of 50% will have 46 ggp at 65 degrees but 124 ggp

at 95 degrees - nearly 3 times as much water! If it is 95 outside and

65 inside, then opening your windows would increase the water in the

air in your house. In fact, it might make it rain inside your house

because 124 ggp at 65 degress is above In fact, it would raise the RH

inside to 100 percent at 74 degrees. At 65 degrees it would probably

be raining. Ouch!

Think it's impossible to rain inside a building? Maybe it won't rain

in the living quarters but it certainly does in a cool crawlspace

during high humidity.

An you thought mold was complicated.

Carl Grimes

Healthy Habitats LLC

-----

> Hi Carl,

> Your response sheds a lot of light on problem! I tune into the

> weather channel daily to see what humidity is outside. If it is 50%

> or below I open my fresh air intake for the day thinking I'm bringing

> in dry, fresh air, but humidity goes up anyway, and I have to run

> dehumidifiers all day anyway. You are explaining reason is that when

> air comes in and mixes with cooler air inside, it becomes more humid

> than it was outside. One really needs to take a course in keeping a

> home healthy!! It isn't so simple. The air in my house all winter

> long is so nice and fresh. I have the fresh air intake open all

> winter long and cold dry air comes in, mixes with inside air before it

> reaches furance, gets heated by furnace and then is distributed

> through rest of the house. House smells as fresh as outdoors all

> winter long. All summer though I have stuffy house, struggling to

> keep humidity down even though weather channel says it's beautiful,

> sunny and humidity 50% or less. So if I want that outside 45-50% humid

> air inside, I have to let inside temperature be the same as outside

> basically (or higher), but there isn't enough air circulation inside

> to feel as nice as outdoor. I have to get some fans going, and dust

> really well first!!! Ceiling fans would be great but I'm not going to

> make those changes in a house I plan to leave in the not too distant

> future. Thanks!

>

> > > Barb, > > You always have such good questions! And this is

> a doozy. > Dehumidification and drying are complex topics derived from

> the > science of Psychrometry. Not " psycho, " but " psychro. " It is a

> COMPLEX > topic because there are several variables that must be kept

> in > balance and they don't change in a simple linear manner. I'm far

> from > an expert here but I can say that some of the most heated

> debates > I've witnessed in the industry are over this topic.

>

>

>

>

>

>

>

>

[Guest guest]

Hi Carl, Well thanks for the compliment (!!!) but I'll have to study

this answer. Weighing a pound of air is something difficult to

understand. Anyway, I get the general idea of cooling air increases

humidity. Now, how to make peace with summertime in my house! I

guess I'll just have to run the AC. At the end of the day to make

it comfortable at night, I throw on a sweater and I turn the AC way

down to kind of 'wring the water' out of the air, then afterward

turn the temperature back to where I like it (about 75). Usually

this works for the night since it is cooler outside and humidity is

less.

I guess I'll just continue to run the dehumifiers in the daytime to

keep humidity less than 50% and at night do the routine above. By

wringing the water out of the air at night, it allows the stand

alone dehumidifiers to turn off for awhile and then we can listen to

television or radio in some peace and quiet for awhile.

I could experiment with shutting off the fresh air intake entirely

to see how air feels but it made a huge difference in how fresh air

smelled when I installed it. I can set it to be on constantly which

is what I like but dehumidifiers cannot keep up when it is open all

the time. So I have it set to open only when the AC kicks on, but

even with that limited use, it does make it harder to keep humidity

down in house. The only other option I see is to put in a whole

house dehumidifier like the Therma Stor right into the ductwork. It

has a fresh air intake opening that so fresh air would be

dehumidified before it enters the home but it's about 1500.00.

However the intakes aren't that large. For house the one is 10

inches I believe and the outside intake was 6 inches, so I assume it

will only be dehumidifying a 'portion' of the indoor air since I'm

pretty sure my cold air return intake is much larger than 10

inches. I have a 35 year old system though. Maybe today's have

smaller cold air returns. I don't know. I was surprised by this.

If I felt it would take ALL the indoor air and outdoor intake air

and dehumidify the cost would be worth it. However just taking a

portion of it and dehumifying it, I'm not sure it that would be

worth it because perhaps my room dehumidifiers would still need to

be run and that would be an awful lot of electricity.

Oh well, that is where I am at. I wish I could get air in house in

summertime to feel as good as it does in wintertime. It's a very

old house. I'm sure it's full of spores and microbes of all sorts

and keeping the humidity down is serious business right now since

I'm not in good health.

Now I know why you can make a career out of this. It's complicated

stuff.

--- In , " Carl E. Grimes " <grimes@...>

wrote:

>

> Barb,

>

> Not only do you ask good questions, but you understand quickly.

> Therefore, you get the next lesson in humidity.

>

[Guest guest]

I just realized when I reread my below post that I am *assuming*

humidity is less at night because it's cooler but following what you

told me, it may not be less but higher. I don't know. I don't check

on the humidity at night. I just assume it is lower since it's cooler

and cooler air can't hold as much humidity but it has to hit a certain

dew point to drop it's moisture, so I need to check with weather to

see what humidity level is at night before turning my dehumidifier off

and opening fresh air intake. Humidity level in house HAS always been

above 50% when I wake up in the a.m. Maybe humidity was not low at

all and the humidity level was creeping up all night long.

Apparently the safest thing is just to leave dehumidifier on all the

time, through the night and day also. I'm just so relieved when I

hear it go off in the fall. I'm tired of the noise and it's a sign

that summer is over and pretty soon air inside house will be crisp and

fresh again. I wish there was a better way.

I turn dehumidifier off at night since it is cooler outside and

humidity is

> less.