How to Dehumidify Basement with Multiple Sections?

[Chevy-SS]

My basement if fairly large (~1,600sf), and is divided into about 5 sections. It is completely unfinished. It also has two sump pumps. I have a temp/moisture gauge down there, and my humidity level is at 75%, plus there is a musty smell.

I am going to add dehumidifier(s), but I guess my big question is: how many? Does each section need its own dehumidifier? And is it best to buy machines with more capacity than needed?

Are there any particular types of machines that are 'better'?

I am planning to have them drain right into the sump pumps.

Thanks for any tips or feedback. Dave F. in Rhode Island

 

[lilredex]

If you have a forced air system, it is best to put your fan on continuous operation to keep the air circulating. That is how I do it, no dehumidification needed. My house is about 1000 Sq. Ft.

The PO installed a floor inlet to the return air duct, which helps.

 

[Kaizen]

I just kicked mine on. I have to run it july-october to keep that musty smell out. i have a dirt unfinished basement about 1000sq ft. I got the attached. Has an internal pump that pumps it outside so you might not need that. No fans besides the unit itself. Moisture seems to just wick into the air pretty quickly. These are expensive to run so i would start with one large vs 3 small. Basically an air conditioner that kicks out lots of heat into your house.
https://www.amazon.com/gp/product/B01N7K57SE/?tag=atomicindus08-20

 

[Showkey]

Running forced air furnace will not work if the 1st floor level is NOT sealed or consistently air conditioned.

I am assume the first floor is not air conditioned.........if it was AC the basement and most of the humidity problem would disappear. Even with AC some basements need dehumidifier to control the moisture.

Run a large dehumidifier and run a box fan to circulate the air. Once the basement reaches 50% humidity you cut back but not stop on the circulation to Lower the power consumption. If the basement is really segmented.......run two smaller dehumidifier at opposite ends.

Yes........75% humidity is a problem for mold, mildew, funky odor etc

 

[kTHREE]

I run mine from midnight to 6am every day, on continuous run, with a heavy duty timer thingy from April to Oct, 70 quart. Make sure your sump pits are sealed up well.

It's WAY easier to keep the humidity down from the beginning of the season than it is to catch up later. The first year in my house I got a dehumidifier in July and it never really made a dent all summer. The next year I started it early and it maintained ~50% all summer.

 

[Chevy-SS]

If you have a forced air system, it is best to put your fan on continuous operation to keep the air circulating. That is how I do it, no dehumidification needed. My house is about 1000 Sq. Ft.

The PO installed a floor inlet to the return air duct, which helps.

I do have forced air (gas) system. But it is sealed off from basement air. I have two window units that A/C the first floor, and do a pretty good job of keeping it cool.

I just kicked mine on. I have to run it july-october to keep that musty smell out. i have a dirt unfinished basement about 1000sq ft. I got the attached. Has an internal pump that pumps it outside so you might not need that. No fans besides the unit itself. Moisture seems to just wick into the air pretty quickly. These are expensive to run so i would start with one large vs 3 small. Basically an air conditioner that kicks out lots of heat into your house.
https://www.amazon.com/gp/product/B01N7K57SE/?tag=atomicindus08-20

Thanks

Running forced air furnace will not work if the 1st floor level is NOT sealed or consistently air conditioned.

I am assume the first floor is not air conditioned.........if it was AC the basement and most of the humidity problem would disappear. Even with AC some basements need dehumidifier to control the moisture.

Run a large dehumidifier and run a box fan to circulate the air. Once the basement reaches 50% humidity you cut back but not stop on the circulation to Lower the power consumption. If the basement is really segmented.......run two smaller dehumidifier at opposite ends.

Yes........75% humidity is a problem for mold, mildew, funky odor etc

1st floor is A/C with two window units, temps and humidity levels are good for 1st floor. Yeah, I am thinking I need two dehumidifiers.

I run mine from midnight to 6am every day, on continuous run, with a heavy duty timer thingy from April to Oct, 70 quart. Make sure your sump pits are sealed up well.

It's WAY easier to keep the humidity down from the beginning of the season than it is to catch up later. The first year in my house I got a dehumidifier in July and it never really made a dent all summer. The next year I started it early and it maintained ~50% all summer.

Good ideas, thanks. my sump pits are wide open!

 

[yeldogt]

Have you looked around and thought about were the moisture is coming from ?

Dirt floor .. wet walls or running water need to be fixed or you will never get the moisture out. If there is water in an open sump pit it has to be covered ..... or the water will enter the air as you remove it.

Do some searching -- the commercial grade units will remove much more water and do so at lower electric cost

 

[Jackfre]

I was speaking with a friend in Vt the other day and he told me he had gone with a heat pump water heater and is very pleased with the economy of operations and the job it is doing helping with the humidity. The utility rebate about paid for the unit. You say the unit has separate areas. How are they divided? If it has sheetrock walls I would suggest you cut high and low through registers between the rooms. The air wants to move. You have to give it a simple pathway to do so. I wall mounted my humidifier in the basement when I lived in MA. That way a simple gravity drain to either your sewer or sump pump.
Yeltdog is on the money here. My basement was a pitn. Dark, dank, wet! I hit the walls with UGL etch and put a coat of the UGL paint on the walls and it made a solid difference in the space. It was worth doing. Sorry I cannot suggest a brand of de-hu. Seems I just replaced them about every 3-4 yrs.

 

[yeldogt]

In an old house with true cinder walls .... a proper coating of cement based paint can do wonders. A dirt floor has to have a rat slab ... or --- if a crawl space covered with plastic.

When I was doing rehabs years ago -- I had a few bungalows with shallow basements because of high water table. High water tables don't just allow water to enter the slab from under it ..... they keep the ground around the building wet. It makes proper grading and downspout control very important.

I watched the walls and addressed any evidence of water ...... installed a good sealed sump and had cement based coating sprayed on the foundation. Opened up the HVAC to the basement.

The heat pump water heater is a good idea for many .... dehumidifiers are expensive to run. You are better off directing AC if in the house when in use ... only dehumidify when colder and AC not needed. In the winter with heat it's often not needed ..

 

[jabin]

Do not use the forced air whole house blower on 100% to lower humidity. The system will only dehumity when the A-coil is cold enough to attract the moisture in the air but when the system turns off, those coils are still covered with water. If the fan is set to On the fan will blow air over those wet coils causing that moisture to now move back into the conditioned air, back where it came from.

The AC unit should be used to control air temperature and a dehumidifier should be used to control Humidity. Just because an AC system can dehumidify doesn't mean it's the best choice.

Also, do not have the box fans blowing on the dehumidifier because it lowers their effectiveness since they are attracting moisture, you don't want to try to dry them with your box fans.

 

[mike93lx]

Either multiple units or move air around some other way.

I recently purchased a Midea on Amazon to replace a failed unit that I run in my garage and am very happy with it. Extremely quiet and it is doing a good job keeping my garage dry. Another will be here tomorrow for the basement

 

[yeldogt]

Do not use the forced air whole house blower on 100% to lower humidity. The system will only dehumity when the A-coil is cold enough to attract the moisture in the air but when the system turns off, those coils are still covered with water. If the fan is set to On the fan will blow air over those wet coils causing that moisture to now move back into the conditioned air, back where it came from.

The AC unit should be used to control air temperature and a dehumidifier should be used to control Humidity. Just because an AC system can dehumidify doesn't mean it's the best choice.

Also, do not have the box fans blowing on the dehumidifier because it lowers their effectiveness since they are attracting moisture, you don't want to try to dry them with your box fans.

This is often reported .. but in real life operation I have never found this to be the case in my eastern climate .... even on the ocean. Now -- even when I was a kid back in the late 60's the system in our places were sized reasonably. We always kept the fans on. My guess is the more oversized the system the bigger problem this becomes as the unit is on and off too much

 

[Showkey]

Also, do not have the box fans blowing on the dehumidifier because it lowers their effectiveness since they are attracting moisture, you don't want to try to dry them with your box fans.

The OP has multiple or segmented basement rooms.........the box fan use was to Mix or move the air from the “ distant more humid rooms“ to the dehumidifier location. A closed up basement the air is not going to move on it’s own. Couple for Small fans on low speed would be enough move the air around.