Air exhaust fan for basement?

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Old 07-17-14, 12:18 PM
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Air exhaust fan for basement?

My basement is finished and split in half one side is a playroom. The other side 25' x 8'. this side houses my oil furnace, washer, dryer, toilet, sink. I use a dehumidifier in this room and on very humid days it takes out alot of water and the 2 windows I have closed in this room as well as the door to the playroom to help keep humidity out. I was wondering if I put an exhaust fan similar to my bathroom where I can easily duct it outside next to the dryer vent. Would this help replace the use of the humidity in this room?
 
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Old 07-17-14, 12:31 PM
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An exhaust fan would result if replacement air ultimately coming in everywhere from the outside. In winter that air is dry so it does work to reduce relative humidity (RH). But the term "relative" in the RH means as warm summer air infiltrates a home and cools down, the RH number will go up. At whatever the dew point temperature is, ir reaches 100% RH and can condense out as water.

Your best approach to reduce the RH in the basement is to identify where the moisture is coming from. Since moisture vapor can pass right through concrete, managing drainage around the house is the first place to start. All rain that falls on the roof needs to be directed well away from the home. If it soaks into the ground next to the house it will show up as humidity in the basement.

Bud
 
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Old 07-17-14, 06:19 PM
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the basement is underground the drainage is away from the house but since its underground I am sure that doesn't help. The walls in the basement are dry I redid the playroom with a new carpet and I sealed the floors before I put the carpet etc. I was hoping an exhaust fan would help in the summer humid days. In the winter the basement is usually fine.
 
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Old 07-17-14, 07:00 PM
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When you blow air out, where is the replacement air coming from?
Are you running air conditioning?

All homes leak air in and the same amount out. A typical home will exchange ALL of the inside air with outside air every 3 hours. If it is humid outside, that is the moisture you are trying to remove. Add in some from the basement walls and floors and it becomes very humid.

Do you have any numbers, RH in the house, basement, and outside?

Bud
 
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Old 07-18-14, 08:33 PM
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I think I need to purchase a device to measure those parameters
 
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Old 07-29-14, 07:44 AM
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So I purchased a humidistat to check humidity levels on one side of my basement (playroom) The other side laundry/boiler room I have a dehumidifier running which shows levels at 60. The humidistat in the playroom and the foyer area show 65 which is high. I understand to find source of the humidity. The basement is underground so I don't think it will ever be 100% moisture free. I also sealed the floor with Radonseal before replacing the carpet to prevent any water seepage which was a minor issue due to efflorescence in the old carpet but other wise there has been no water issues seen in the basement. Central Air including the playroom should help with the humidity levels. But I feel like its a battle to get all these areas humidity free. I was hoping an exhaust fan would help in the boiler/laundry room I have the windows closed as well to prevent humidity from entering to help combat. The foyer I have Damprid in the food closet and coat closet but noticed moisture being pulled using damprid in the food closet and dry in the coat closet. Any other ideas I should look into. Thanks
 
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Old 07-29-14, 07:47 AM
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Is there airflow between the area with the dehumidifier and the playroom? If not, that's what I'd be working on, as the dehumidifier is the first thing I look for in a humid basement and whether that air can circulate is critical.
 
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Old 07-29-14, 07:57 AM
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The boiler room that has the dehumidifier has 2 windows should I open them for airflow? I think this is what you refer to. I thought that would bring in more humidity. The play room has 2 windows closed but the central air is on so the windows remain closed.
 
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Old 07-29-14, 08:04 AM
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No, I don't mean airflow in from outside, I mean does the air in the room with the dehumidifier flow into the playroom? In other words, does the playroom get any benefit from the dehumidifier like is there a vent from the air conditioner in the boiler room so that air is being pushed out of the room?
 
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Old 07-29-14, 08:35 AM
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The boiler room is closed by a door so that the AC can work in the play room and the dehumidifier work in the boiler room. I can open the door and run the ac and dehumidifier together. I tried shutting the AC vent in the playroom and running the Dehumid in playroom but not sure what the best setup is.
 
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Old 07-29-14, 08:55 AM
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Leave the door and the vents open and see what happens. I end up closing some of the vents in the basement in the summer when the AC is running (otherwise it's too cold down there) but the one in the utility room where the dehumidifier is stays open so the inflow of air helps push the dehumidified air to the rest of the basement.
 
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Old 07-29-14, 11:05 AM
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So I will leave the door from the boiler to play room open as well as the foyer door open which leads to the playroom and leads to the upstairs and garage, the ac vent has been opened. Should I open the boiler room windows? I just thought the dehumidifier and the ac would compete with each other.
 

Last edited by stickshift; 07-29-14 at 11:24 AM. Reason: Removed quoting of entire post
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Old 07-29-14, 11:23 AM
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Don't open a door which goes upstairs nor any windows.
 
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Old 07-31-14, 09:24 AM
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I also realized that my dehumidifier had the relative humidity set at 60 so I have changed it to 50. I hope this helps.
 
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Old 08-06-14, 08:40 AM
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Name:  foyer.jpg
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Size:  19.5 KB This is the foyer area which I think I need to get the doors some ventilation. The bifold door is canned goods etc. the other door is from the garage and the other is to the basement.
 
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Old 08-06-14, 09:20 AM
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had the relative humidity set at 60 so I have changed it to 50.
Good move..... I set mine from 45% - 50%.
 
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Old 04-01-16, 05:16 PM
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Some thinks to keep in mind...
*I don't think that there is a great deal of difference in the amount of humidity that is 'seeping in' into the two rooms.
*The a/c is drying one room and the dehumidifier is drying the other (in the summer).
*A dehumidifier is a very inefficient device in comparison to furnace a/c.
*A clothes dryer exhaust a lot of air to the outside.
*During the winter, heating the upstairs alone creates enough dry air to completely dry the basement by just circulation.

With these points in mind, I would suggest opening all the vents in the basement, replacing the door between the areas with a louverd one and/or add through-the-wall vents - then turn off the dehumidifer and heat/cool the whole basement. Any additional cost for heat and a/c will be less than running the dehumidifer.
 
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Old 04-01-16, 09:21 PM
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Welcome to the forums.

Thanks for the additional information. I'm not sure if the original poster will see it but this thread will remain in our searchable archives for future reference.

After reading this..... if you have a question or need help.... fell free to start a new thread.
 
 

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