My house, built in 1951 has a large basement, actually two "basements" with a wall that looks like 2X4's and paneling separating the two halves at the stairs. It appears the one half was once finished and used for something as it has a finished ceiling and what was a bar of some sort. The other half has exposed joists and wiring, plumbing, etc and where the heater, water heater, laundry area are.

It's been very musty and dank down there (but thankfully NO visible water!) with it basically down-pouring for the past 10 days or so every day. I should have dug out my dehumidifier before and got it running a while ago, but finally did yesteday.

It's a Haier 45 pint model and I have it running a hose that leads to the large floor drain on the laundry/heater side of the house. Seems to be bringing the humidity down quickly, went from 75% to 58% in about 15 hours on that side. On the other side, it's still at around 62%. I have the dehumidifier set to 52% humidity level on the "smart" setting.


My question is: Do I need to get another dehumidifier for the other side? Or could I possibly cut a hole in the "wall" (which I could care less about at this point) and put a large fan there to pull in the air from that side to be conditioned? I'd rather not be running two of these as they do add to the electric bill.

I'd say the two spaces are about 30' X 30' each, so that's two spaces of 900 feet each or 1800 square feet total of basement space to be dehumidified.

It looks like the 45-pint unit can handle up to 2500 square feet?

I run two in a 980 sq ft bone dry basement. Both drain continuously. Keeps it below 40% year round. Have my gun safe down there and no rust forms.

I would cut a panel in the wall first. Needs to be large enough to get some air flow between the two spaces. I probably would not add a fan. The dehumidifier itself should be creating some significant airflow, so I’d just open up the space and see what it can do on its own. Like you say, cheaper than buying/running a second unit, and those things don’t last all that long.

Of course, I like to keep my basement 45-50%. If you want to go much drier than that, you may need two.

I'd let that run a week before judging success. The accumulated moisture content it's fighting isn't just in the air. That's a pretty good drop for less than a day in that environment.

Some REALLY REALLY big desiccant packs?

It sounds like the humidity is coming down in both rooms. I would not worry about holes in the wall at first, but locate the dehumidifier in the same room with the laundry, as that can be a large humidity creator.

Let it go a few more days and see if further changes are needed. It seems to have improved both rooms very quickly.

Assuming the measurements area right, industry standards that I work in would put you at 144 pints according to AHAM ratings if you had a water damage. You don’t need that to maintain your RH around 50%. What you have is probably sufficient, just a matter of letting it catch up. A hole in the wall and a simple box fan would certainly help if you want to go through the trouble.

quote:

Originally posted by MattW:
You don’t need that to maintain your RH around 50%.

What should I keep it at then?

Prior to turning the dehumidifier on, it was 75% RH down there.

quote:

Originally posted by PASig:

quote:

Originally posted by MattW:
You don’t need that to maintain your RH around 50%.

What should I keep it at then?

Prior to turning the dehumidifier on, it was 75% RH down there.

I think you're misreading him, he's saying you don't need the larger unit to maintain 50%.
If it was me I'd let what you have run for another couple days to get all the latent humidity out, and see where it levels out at.

There was a massive recall of dehumidifiers a year or two ago. It involved numerous brands. You should check to see if your model is on the list.

quote:

Originally posted by PASig:

quote:

Originally posted by MattW:
You don’t need that to maintain your RH around 50%.

What should I keep it at then?

Prior to turning the dehumidifier on, it was 75% RH down there.

60% RH sustained is generally considered when mold is capable of growing. When I lived in an area where basements were common, my general rule was 50-55% RH is ideal. Maintaining that under normal conditions with an off the shelf dehu isn’t too hard. If you have central air, be sure the registers to the basement are open to help. In the event of a 10 day rain storm, that little guy will run and run as you’ve found out. That 45 pint manufactures rating is BS, AHAM rating would probably put it in the 25-30 pints per day range if I had to guess.

If you have a safe or gun components in the basement, it probably wouldn’t hurt to keep the RH a little lower I suspect. That may require a second or larger dehu however.

Temp will impact the efficiency of your dehu too. Our commercial grade ones are most effective in the 75-90 degree range. Some can go higher in temps while our desicants can work in much cooler environments. Pay close attention to the manufacturers recommendations to get your ideal temp. Can always pick up a hygrometer to see where the room is compared to the output of the dehu. Your grains per pound difference will tell you the most information as to how affective it is working. A large negative difference in the ambient air and the dehu output air in the grains is about the simplest way to explain what you’re after. Most off the shelf hygrometers won’t give you the grains per pound (GPP), but Phoenix Restoration Equipment has a very simple free app you can use, just spin the little wheels to the correct temp and RH to get the GPP.

I have two dehumidifiers running 100% of the time (except for their frequent failures). Both are 70 pint machines and I am attempting to maintain 50% RH a about 78 degrees.
My basement is 1008 sq ft with about 8.5 ft ceilings mostly finished.
Closed off garage space which is used for reloading, cabinet work, & etc. is smaller at about 360 sq ft and 9.5 ft ceilings but with much more traffic.

I don't care anymore what the box indicates, I know that smaller units simply will not make the cut that is to say not get to 50% during humid days & nights, they run too much---sometimes continuously, and fail sooner.

I would buy bigger units and higher quality if they were easily available. In fact I have considered a crawl space dehumidifier which costs $$$$. I am very serious about out this because I have a substantial investment in tools to protect from rust.

For those looking for a serious dehu, these are where it’s at. Suspect you won’t find many used ones out there as this model is fairly new, maybe a demo model if you shop around and are patient. They have a display that will give you input and output for temp and RH. These are a fraction of the size of the older units in the industry.

https://www.google.com/shoppin...DwlkKHcvuD8AQgjYIiwQ

I'm under the impression dehumidifiers take a lot of power, and therefore a lot of extra $$ on the electric bill each month. Am I wrong?

quote:

Originally posted by radioman:
I'm under the impression dehumidifiers take a lot of power, and therefore a lot of extra $$ on the electric bill each month. Am I wrong?

My consumer grade unit running all the time in an uninsulated unoccupied concrete block cabin in Alabama on a lake uses about one dollar a day of electricity. For the change in humidity and dampness, it is well worth it for that thing to run all off-season long.

Basically all the dehumidifier is just a small/tiny refrigerator. Except both sides are open to the air. The cold side needs to get below the dew point to catch water. You can do some basic math if you can find the watt rating of the one you're looking at.

Just like an air conditioner, a big one that cycles isn't as effective as a smaller one that just runs continuously. Let it run its heart out for you. No reason to be easy on it, let her rip.

quote:

Originally posted by radioman:
I'm under the impression dehumidifiers take a lot of power, and therefore a lot of extra $$ on the electric bill each month. Am I wrong?

Mine was adding $20-$25 to the electric bill last spring/summer, well worth not dealing with mold and mildew down there.

Most older dehumidifiers don't work below 55 degrees. Most modern examples have a deicer for lower temps, which is important for your application.

Don't go cheap when you buy. The problems with fire are real. I got lucky in that the model I was using just quit without catching fire.

V.

PASig,

Out of curiosity, is your basement conditioned space...as in do you have HVAC ducts/vents ran to cool/heat the space and move air around? While this will not eliminate your problem, having cold air returns in the basement to get sucked into your HVAC system will certainly help circulate the air and if you have AC, it will help to strip "some" of the humidity.

My basement is 2/3 finished/insulated and the only space where we have moisture issues is on the non-insulated side. More than likely I will be finishing this space with 2" of rigid insulation. Again, it may not eliminate the problem, but it will certainly diminish it.

So, the dehumidifier has been running nonstop for a week now and the best I can get is about 58%-59% RH on the side the dehumidifier is on and 60%-62% on the other side.

I cut a hole in the paneling that divides the basement and placed a box fan to suck air into the side the dehumidifier is in, and in the doorway between the two basement halves I placed another fan blowing air from that side back into the non-dehumidifier side.

I have the dehumidifier set now to 45% and want to get the basement to around 55% RH but it just can't seem to.

What's going on here? Is 58%-62% OK? The musty damp smell and feel have gone away. We continue to have very damp and rainy weather around here which is not usual at all for this time of year, I think we've had rain 12 out of the past 15 days or so.

quote:

Originally posted by jcsabolt2:
PASig,

Out of curiosity, is your basement conditioned space...as in do you have HVAC ducts/vents ran to cool/heat the space and move air around? While this will not eliminate your problem, having cold air returns in the basement to get sucked into your HVAC system will certainly help circulate the air and if you have AC, it will help to strip "some" of the humidity.

I do have ducts down there that have vents that can be closed or opened, right now they are all closed. I don't see any vents on the returns.