Humidity in Basement

[PastorPaul]

In spite of having a dehumidifier in the basement, the humidity is so high that condensation is running off the outside of the window on the door. The lawn chairs we have left in the basement for tornado season are getting mold on them. How do I get rid of the problem, prior to getting some of the leaks in the wall fixed?

I know one problem is that the temperature in the basement gets so cold that the dehumidifier freezes up. An HVAC technician told me that cool temperatures cause this even with brand new dehumidifiers.

I am looking at two things to attempt. One thing I plan to do is to put a few of those small round vents in the sidewalls of the cover over the outside basement stairway. That will provide some ventilation and some escape for the moisture on that side. The other thing is to open the vents to the crawlspace (I'm used to vents that are open all year long), then open the little doorway that gives access to the crawlspace from the basement. I figure that would give some additional ventilation and further reduce the moisture trapped in the basement.

Any pros or cons on either of my ideas? Also, anybody have other suggestions?

Pastor Paul
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"If they don't have woodworking in heaven, I ain't going!!!"

[jimpen]

I would also suggest putting in some space heaters for now. Try to bring the temp up a few degrees to give the dehumidifier a better chance of working.

[deathwish2]

Moisture on the windows is excessive. If it's nowhere near that humid outside (I can't imagine it would be, this early in the season), it's coming somewhere from within.

One thing you may want to check is that there is a pump or at least somthing other than a floor drain taking care of the water from your A/C condenser. That will produce a lot of water in humid weather. If it just trickles into an open floor drain, the drain could be your source of moisture. If it goes into a trough and gets pumped out into the DWV system (most overhead units I've seen are like this), it's a non-issue.

I remember in another post you mentioned that part of the basement was a dirt floor (or was it just your crawlspace) . . . is that earth moist still? If so is it a water table issue, or is there gutters/downspouts feeding onto/into the ground right near the foundation?

--Mark

When it comes to
woodworking and buying
tools, I always think back to
my grandfathers advice on
golf . . . "it's not the arrows,
it's the indian.''

[PastorPaul]

>Moisture on the windows is excessive. If it's nowhere near
>that humid outside (I can't imagine it would be, this early
>in the season), it's coming somewhere from within.
>
We have had a great deal of rain the last week or two, and extremely high humidity the last month or so. Missouri is worse than Iowa was for humidity.


>One thing you may want to check is that there is a pump or
>at least somthing other than a floor drain taking care of
>the water from your A/C condenser. That will produce a lot
>of water in humid weather. If it just trickles into an open
>floor drain, the drain could be your source of moisture. If
>it goes into a trough and gets pumped out into the DWV
>system (most overhead units I've seen are like this), it's a
>non-issue.
>

Just a floor drain. Would it make sense to run both the dehumidifier and the condenser into a small sump with pump and send the output outside? Running it to the DWV system would be putting the rain water seepage in there as well.

>I remember in another post you mentioned that part of the
>basement was a dirt floor (or was it just your crawlspace) .
>. . is that earth moist still? If so is it a water table
>issue, or is there gutters/downspouts feeding onto/into the
>ground right near the foundation?
>

The basement floor is all concrete. The crawlspace is dirt, but every time I check it, it is dry. That's why I thought it might be good to get some air circulation going by installing vents, opening the doorway between the basement and crawlspace, and opening the vents in the crawlspace wall.

For now, I am just trying to deal with the humidity until I can do the concrete work necessary to reduce or eliminate it.


Pastor Paul
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"If they don't have woodworking in heaven, I ain't going!!!"

[Bob Crosley]

The best advice I've heard for improving your effectiveness of your dehumidifier is this:

put an oscilating fan at the opposite corner of the basement pointed up at the ceiling and aimed in the general direction of your dehumidifier. Put it on an appliance timer for 6 hours on and two off so it's running 18 out of 24 hours. That gets the rest of the basement air moving and moving toward the dehumidifier. Problem is that without circulation, you get the area around the dehumidifier dry but the rest of the basement is left wet.

I'd try that first, before you start cutting into walls to put vents in. I've heard it can seriously boost the efficiency of your dehumidifier.

Bob

[deathwish2]

>Just a floor drain. Would it make sense to run both the
>dehumidifier and the condenser into a small sump with pump
>and send the output outside? Running it to the DWV system
>would be putting the rain water seepage in there as well.

If you are on septic, that's an issue, if you are on city sewer, they only bill based on what you take from the tap. While it's likely illegal in your area to send your sump pump into the sewer system, the moisture from the A/C should be fine on it's own, that is how they do it in office buildings with suspended ceilings and the like.

>The basement floor is all concrete. The crawlspace is dirt,
>but every time I check it, it is dry. That's why I thought
>it might be good to get some air circulation going by
>installing vents, opening the doorway between the basement
>and crawlspace, and opening the vents in the crawlspace
>wall.

Circulation is good, but if you start getting a lot of airflow going, don't bother running the dehumidifier . . . unless it's a BIG one (not a little 25 or 40 pint model) it won't keep up with the air exchange of a fan vent . . . you'll just burn up a lot of electricity drying up the fresh air you are drawing in . . . . those units use as much electricity as a window mount A/C. If you do use fans to force some airflow . . . see if you can force the air towards crawlspace rather than drawing the air in from it . . . no sense taking chances that the ground is the source of some of your moisture.

--Mark

When it comes to
woodworking and buying
tools, I always think back to
my grandfathers advice on
golf . . . "it's not the arrows,
it's the indian.''

[PastorPaul]

Bob,

The vents I need to install are just small vents in the sidewalls of the outside basement stairway. Even though there is some air leakage around the doors, the humidity is also building up in the stairway and the vents would give that a chance to escape, or at least let in some fresh air to reduce the musty smell.

That fan idea sounds pretty good. I have both a fan and a timer that are not in use right now.

Pastor Paul
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"If they don't have woodworking in heaven, I ain't going!!!"