Basement humidity

[JHZR2]

How dry is your basement?

I have a santa fe dehumidifier that runs all the time in there, and an LG small one in my shop. The basement is maybe 30x30.

I cant get it below 58%.

Upstairs is warmer but far dryer in the winter. I understand that it is relative, but Im still concerned with mold.

No water in the basement ever. Had an interior curtain drain put in with sump hole (never had one before), and the sump hole never has water in there besides what the dehumidifier drips in there. It is covered so it isnt evaporating back.

ideas?

 

[brentalan]

I have the same problem. I eventually had to upgrade to a more powerful dehumidifier. On really humid summer days I ran both of them together and that worked really well.

 

[Boomer]

Brentalan is right. You just need more dehumidification. Either buy a second unit or get a larger capacity unit. Either way will get that RH value down. Any thing you store at higher humidity, particularly paper and wood items, can become a host for mold and mildew.

 

[Rand]

how is the air circulation in the basement? maybe a small fan to move the air around might improve the dehumidifier's efficiency?

A 20" box fan doesn't use very much power.. might be worth a try.

 

[dparm]

Too low and you will notice a lot of static electricity. That's bad if you have electronics down there (TV, amp, computers, etc).

 

[demarpaint]

My dehumidifier hardly runs during the winter, I heat with a wood stove and forced hot air. Mostly wood though. During the summer it runs non-stop, no mildew issues to report.

 

[jg1]

The effectiveness on the idea below depends a lot on the house, but worth considering.

The idea is to draw drier air from the upstairs dwelling, across the basement and vent to the outside. It is done at a low air exchange rate. It is the most effective when the inlet and outlet are at opposite ends of the room/basement and there aren’t other openings. i.e. A vent is in the basement ceiling at one end of the basement and the outlet pulls from the basement FLOOR as the opposite end drawing air to the outside. If the basement is used often and the stairway door (if applicable) is always open then the inlet vent to the basement from the upstairs dwelling isn’t needed (not as ideal, but will work).

Use a off the self fan like this:

http://www.amazon.com/Diversitech-625-AF8-Round-Duct-Fan/dp/B001O6ECRG/ref=pd_sbs_ol_5

This is an 8”, you can choose a 6” or 10” for more or less CFM.


There are systems that will do the above, and they contain a humidity sensor for auto shutoff and are $. With the fan only using the equivalent of a 40watt bulb the cost savings of doing the system on the cheap has its pluses. Always trade offs.

This most likely wouldn’t replace you dehumidifier, but should help get the humidity down some more.


take care.

 

[Al]

Raise the temp, use a higher dehumidifier and perhapst Drylock on the walls.

 

[JHZR2]

I have this:

http://www.thermastor.com/Santa-Fe/

Plus an LG small unit.

Should be good for 2400 sq ft, more than I need.


It runs all the time, to the tune of $100/ mo.

It is working, but dont see a ton of water from it. The basement isnt warm though.

 

[Pop_Rivit]

Our basement is vented and conditioned the same as the rest of the house. The basement is on it's own zone, and the humidity/temperature is exactly where we set it-about 65 in the winter and the humidity stays about 40%. We have a humidifier on the heating system, otherwise it would get too dry in the winter. Summer months the humidity may get up to 45%, but never higher than that unless we have all the windows open on a humid day.

The finshed square footage of just the basement is about 1800 square feet (house total of just over 4000), and our total monthly electric bill is about the cost of your dehumidifier alone.

When we built we made sure the foundation was drained, sealed and insulated. Knowing the basement and walkout would be finished I made sure that humidity, mold or moisture would never be an issue. The walkout/glass wall faces the west/south and gets great sun in the winter and heats the stone tile floor. The window coverings get closed at dark, so we retain the heat in the basement. The thermal heat also helps keep the humidity low.

 

[doitmyself]

Originally Posted By: Pop_Rivit
The finshed square footage of just the basement is about 1800 square feet (house total of just over 4000), and our total monthly electric bill is about the cost of your dehumidifier alone.


Your electric bill is $1,500 per month?

 

[Smoky14]

Currently mine is 15% and will dry out come spring. Something to be said for the SW. Tools don't rust unless youn really mess up.

 

[dwcopple]

Originally Posted By: JHZR2
It runs all the time, to the tune of $100/ mo.

Dear Lord

 

[KrisZ]

Is this a heated/conditioned basement? Also, does the furnace draw the air from the basement or outside?

If the furnace draws the air from the basement, then it might be pulling outside, humid air into the basement. If that’s the case, the dehumidifier will have a hard time keeping up.

High humidity, in an otherwise dry house almost always means air penetration.

 

[JHZR2]

Is this a heated/conditioned basement? Also, does the furnace draw the air from the basement or outside?

If the furnace draws the air from the basement, then it might be pulling outside, humid air into the basement. If that’s the case, the dehumidifier will have a hard time keeping up.

High humidity, in an otherwise dry house almost always means air penetration.

This is an 80+ yo home, the basement is what it is. I have an ultra high efficiency boiler, so it pulls outside air and then exhausts outside.

The house surely doesn't have the greatest insulation, being as old as it is, and a balloon frame design.

But the walls are not wet or damp, and there is no water issue. The walls are drylok'ed, but they are "covered" with a metal mesh and parging that is 50 years old. So who knows how humidity diffuses through.

 

[doitmyself]

The fact that the units are running 24/7 and pulling little water out of the air......are you sure that they are working correctly and/or could your humidity meter be off?

 

[JHZR2]

The unit cycles on and off. There are times when it actually turns off. 24/7 is a bit excessive, maybe better to say that I notice it on more than off.

I recently calibrated my meter to 75% via the table salt method. Validated it with another meter, so I know that point is correct.

 

[JTK]

Originally Posted By: JHZR2
How dry is your basement?

I cant get it below 58%.



Geez.. that sounds pretty good (low) to me!

I've got a large basement. Half finished, half not.

We have a large Danby brand dehumidifier with digital controls. You can set it between 35-80% humidity. Anything below ~55% per the machine's display feels very dry, although the basement is always cooler than the house. Anything around 60F and lower and you basically can't run the dehumidifier anyway.


If I set the machine below 65% in the summer, it runs pretty much continuously and won't get below ~60%. I run a drain hose into the covered sump pit nearby.

In the summer, it's like walking into a dry, air conditioned environment in the basement.

No central air in our house due to the hot water baseboard heat we have. We do have separately zoned baseboard heat in half of the basement as well.

Joel

 

[Quattro Pete]

Originally Posted By: JHZR2
How dry is your basement?

I just bought one of those cheap Accurite humidity monitors. No idea how accurate it is, but it hovers around 45% in our basement. We don't have any dehumidifiers in there.

 

[Quattro Pete]

On a related note, has anyone attempted to calibrate their hygrometer using the simple salt method?

http://www.humidor-guide.com/humidor-preparation/calibrating-hygrometer

Not really a calibration, since mine cannot be adjusted, but it should at least tell you how far off your meter is so that you can compensate accordingly. Mine sees to be about 8% low. This means that my basement humidity is actually closer to 53% as opposed to 45% that I reported earlier.