Humidity issue and trying to save $


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Old 10-08-18, 06:03 PM
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Humidity issue and trying to save $

I live in South Jersey...it gets pretty humid here. I just moved into a bi-level home where the downstairs/basement is about 4' under ground level. All rooms are finished besides laundry room. Humidity is commonly 75% down there. There is no door from downstairs to upstairs since its a bi-level style home. There are no water issues with water getting through. We typically don't like to run the central air unless it's pretty hot, however, we did more than usual since moving here (didn't seem to help humidity too much since we keep AC at 78 to save $). We usually keep downstairs windows closed and upstairs windows open. Even when temp is in 70s outsideit is still pretty humid downstairs. I've been just running the dehumidifier downstairs over night, every night and then keeping it off during day. Humidity goes down over night and then returns to 70s during day when dehumidifier is off. This is with windows open OR closed. My thinking was that mildew/mold needs time to grow so having humidity going up and down might be okay so i don't have to run the dehumidifier 24/7. Does anyone know if this method is effective with staying mold free or do i have to give in and constantly run AC and dehumidifier until winter?? Any knowledgeable advice would be greatly appreciated!! Thanks!
Bill
 
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Old 10-08-18, 06:20 PM
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Hi Bill and welcome to the forum. A couple of details will help you understand what is happening. 1. Even with windows closed a house will exchange a lot of air especially when the inside and outside temperatures are different. That means a lot of your moisture is simply outside humidity. And that leads me to #2. 2. The humidity reading you quoted is called RH or relative humidity. The reading varies with temperature. Here is a link to a humidity calculator. Pick up a gauge that measures both temp and humidity at the same time. Plug those numbers into the calculator to get the dew point. Then use that dew point and a reference temp, I like 70°, and calculate the resulting RH. Do that for outside and inside in several locations and you will get an idea where the moisture is coming from. Your ac unit should be able to remove more moisture than the dehumidifier as long as it isn't too big. Large units don't run for long cycles thus don't remove as much moisture. Bud
 
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Old 10-08-18, 09:32 PM
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You are seeing exactly what I would expect - high moisture in a basement which goes down when a dehumidifier is run. My only question is why are you turning it off?
 
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Old 10-09-18, 04:51 AM
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Turning it off to save money, I'm assuming it's pretty expensive to let it run 24/7. Plus, it would have to run full blast all the time since windows are open upstairs, and it makes downstairs pretty warm to run it all the time.
 
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Old 10-09-18, 09:12 AM
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Well, I see two choices - quite opening the windows to let in more humidity or live with the humidity.
 
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Old 10-09-18, 09:37 AM
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thats just it...trying to figure out how long it takes for mold growth. I'm hoping running it overnight prevents enough time for mold to begin to grow, and doing it without running it 24/7. I don't mind humidity, I mind the mold.
 
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Old 10-09-18, 10:46 AM
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Mold grows when conditions are right and it stops and waits when conditions aren't right. So, you could have mold growing when the windows are open and it can slow to a stop when you get the humidity down. Any time the relative humidity is above about 50% mold can grow and it will pick up right where it left off.

Cleaning is one good method for keeping mold under control. Removing any carpet or fabrics from the house that cannot be cleaned will also help.
 
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Old 10-10-18, 12:26 PM
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Mold can grow in less than 24 hours. Keep the humidity under 60% like said close the windows and let the dehumidifier remove the RH. once it gets down it might only have to run 1/2 the day.
 
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Old 10-15-18, 04:58 AM
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Thanks Everyone...will keep it running.
 
 

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