DIY dehumidifier?
February 13, 2010 5:16 AM   Subscribe

Looking for a cheap, simple, DIY technique to dehumidify my apartment.

A few months ago I moved to a new apartment. It's a great place, but the shower has no window to outside, just a fan. Meanwhile the rest of the apartment will get very damp if I don't run the fan all the time, especially after a shower. The windows get massive amounts of condensation and recently I found a ton of mildew on the back of my sofa. It's just too wet. But running the fan means all my warm air--and the money towards my electric bill--gets sucked outside and I have a cold apartment.

Aside from buying an actual dehumidifier, what are some cheap and easy ways to suck the moisture out of the air? BTW, my apartment doesn't have central heat/AC; each room has a wall unit. They do dry the air when I turn them on, but I don't use them so much.
posted by zardoz to Home & Garden (10 answers total)
Does the bathroom have a door? If so, can you just keep it closed during and after your shower?
posted by Cat Pie Hurts at 5:22 AM on February 13, 2010

There is no cheap, non-dehumidifier sort of way to suck moisture out of the air.

The windows can be improved with that plastic shrink film; condensation is happening because the glass is so much colder than the room air. Improve the windows' insulating qualities and you'll reduce condensation. But that doesn't help with the couch.

You can find ways to prevent the moisture from getting into the air in the first place (and the shower seems like an unlikely source for that much water). You can improve ventilation so that the wet air goes out and is (hopefully) replaced with drier air. You can suck the moisture out with a dehumidifier (or with AC, which is a less-efficient dehumidifier). Or, you can lower the RH by turning up the heat. That's pretty much it. If there were a cheap and easy way to suck moisture out of the air, then they wouldn't make dehumidifiers.
posted by jon1270 at 5:41 AM on February 13, 2010

Cheap and easy way to suck moisture out of the air

You should be able to find something like it in Tokyo.
posted by amtho at 5:59 AM on February 13, 2010

The DampRid stuff that amtho linked to is roughly equivalent to the silica gel packets that come with shoes and electronics. It's great for corralling small amounts of moisture in small spaces, or for cheap removal of moisture from a one-time incident (pipe leak, etc), or which has built up slowly over time. I get the impression that the OP is dealing with a sustained influx of rather substantial amounts of humidity, in which case I don't think the chemical solutions are going to be very useful.
posted by jon1270 at 6:42 AM on February 13, 2010

Our bathroom isn't vented, and we had a problem with mildew. The DampRid really helped that. The mildew stopped, and there's something vaguely satisfying about seeing the container fill with water.
posted by Ruki at 6:57 AM on February 13, 2010

DampRid: The Original Non Electric Moisture Abosrber

Got one in my bathroom. Works reasonably well.
posted by meta_eli at 7:09 AM on February 13, 2010

As jon1270 noted, chemical adsorbents like calcium chloride (DampRid) or sodium silicate (silica "gel") have limited ability to dehumidify open spaces and are quite expensive for what limited effect they do have.

Unless you are keeping your sofa in the shower, I think you might best look to finding the major source of water and ameliorating that. I suspect you are living in a basement apartment with leaks hidden behind walls or under carpeting, or the building has a leaky roof which can allow rain to permeate the entire structure and end up in your sofa.

I have no idea of tenant rights in JP, but in the US this would very likely be the responsibility of the landlord.
posted by fydfyd at 7:46 AM on February 13, 2010

I too live in a poorly-ventilated apartment. The relative humidity in here has been over 50% pretty much all winter (I have a fancy digital weather station dealie that shows me).

My bathroom also just has a fan and no window to the outside. I have a little tub of DampRid in there and it does seem to help. It's pretty inexpensive. I paid less than US$3 for the starter tub and a bag of extra crystals is maybe around US$5. I change it about once every thirty days when it's totally dissolved. If you can find this stuff, give it a try -- you won't be out much money if it doesn't work out for you.

I monitor my windows for condensation very carefully and wipe them down immediately if I find any. Cracking the windows when washing dishes or cooking helps.

It sounds like keeping your apartment moderately heated at all times (which helps reduce the overall humidity) isn't really practical. As long as it's not incredibly cold outside, simply opening your windows to increase ventilation may be a better solution than running fans. My experience has been that 45 minutes of open window cuts the humidity by quite a lot, though it will start to creep right back up as soon as they're closed.
posted by trunk muffins at 8:53 AM on February 13, 2010

Your fan should be doing a better job than it is. I would pop the cover off and inspect the blades of the fan to see if they are gunked up (they likely are if the fan has never been cleaned)

The whole fan assembly should come out with a single screw or two, so you can remove the unit for cleaning.

This would be a good starting point for you. Can you see where the fan exhausts outside? Check to make sure that there are no obstructions (i.e. birds nests) that would prevent the fan from working effectively.

If you crack a few windows when you leave during the day with the heaters turned down or off, a lot of your humidity should be sucked away.
posted by davey_darling at 9:52 AM on February 13, 2010

I find the same problem (third floor apartment in Dublin)--have dealt with it by cracking the window open through the day. This hasn't made the flat unacceptably cold even in what is by Dublin standards a very cold winter. Now I just have to deal with the mould stains on the paintwork.
posted by Logophiliac at 2:21 PM on February 14, 2010

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