Hot and humid basement - What to do?

[Sho'Nuff]

Cliffs below for those who don't like to read.

So I recently had my basement renovated. Went from almost totally unusable space to a finished24'24' living room and a 10'X12' adjoining office. Insulated the walls. Ceiling was previously insulated.

Prior to the renovation, my basement stayed at a nice comfortable 68 degrees all year round. What the humidity was at that time is unknown, but there was no condensation formation or other water in the basement. I do have two sumps though, due to proximity to a wetland and because the water table in my area is high.

Once the basement is finished, the humidity spiked way up. Hovers around 80%. I can bring it down to 40-45% with a dehumidifier, but running the dehumidifier (alone or in conjunction with my plasma tv) heats up my nice insulated basement by 10+ degrees, making it stuffy and uncomfortable (yes, 80 degrees is stuffy and uncomfortable to me).

Anyone have any idea what I can do about this?

Options I've considered:

1. Install AC (e.g., a minisplit or portable AC vented out a casement window), but that seems counterproductive as the AC would simply offset the heat produced by the dehumidifier.

2. Install more efficient dehumidifier (e.g., santa fe compact/Rx) in my utility room, duct the inlet air from the living room and have the unit outlet warm air in the utility room where it is insulated from the finished living space. This would seem to have the double benefit of dehumidifying the air while dumping heat where it can be used most, right next to my heat pump hot water heater.

3. Sweat my ass off til winter.

cliffs

-Op finished his basement and it is now humid.
-Running humidifier + plasma TV = Op sweats his balls off because basement temp rises 10+ degrees.
-OP needs options for keeping the space nice and cool, like a basement should be.

 

[dank69]

Use regular lube instead of the warming lube

 

[Sho'Nuff]

Use regular lube instead of the warming lube

Sorry. I like heat with my friction. But not with my basement.

 

[highland145]

-Running humidifier + plasma TV

Start with a dehumidifier.

 

[highland145]

Long term, why is there moisture in the basement? Washer/dryer?

 

[Mixolydian]

A/C will both cool it down and help reduce humidity.

 

[MontyAC]

Run an AC unit in the basement?

 

[Vdubchaos]

Why did you insulate the basement? That's a big mistake.

If you didn't do that, your basement would've maintained a perfect temperature all year round (ok fine, you would need some heat).

In MOST of the cases, insulating basement walls = no no

 

[Imp]

Sounds like your old basement walls were very leaky, air and/or water vapor, and the insulation now traps everything inside -- why I don't believe in finishing basements.

If you don't want A/C, pop a window?

Also, A/C should do some dehumidifying on its own, but its main goal should be temperature. I've done some reading recently and there are people who run A/C + dehumidifier.

 

[Printer Bandit]

you done goofed

 

[Imp]

Long term, why is there moisture in the basement? Washer/dryer?

If he's near a wetland area, the floor slab (and walls) might be letting water vapor in. Otherwise????

 

[highland145]

If he's near a wetland area, the floor slab (and walls) might be letting water vapor in. Otherwise????

Definitely. He mentioned utility room. Wondered if he put the w/d in the basement.

 

[NetWareHead]

Definitely. He mentioned utility room. Wondered if he put the w/d in the basement.

Unless incorrectly installed, the dryer should be exhausting outside.

 

[highland145]

Unless incorrectly installed, the dryer should be exhausting outside.

I'd think there would still be some extra moisture from the both.

 

[fstime]

I would not run a dehumidifier when a a very small AC unit will both cool and dry out the basement.

You do not need to size AC units (or heating) the same way you do normal living spaces because the load is usually much lower assuming your mostly underground.

You can probably get a unit rated at half the recommended sq ft and it would do the job fine.

 

[Sho'Nuff]

Long term, why is there moisture in the basement? Washer/dryer?

Sumps + high water table. Moisture is likely leaching through the slab.

Laundry is on the first floor above ground, though the dryer vent runs through the basement behind a wall. That is temporary though as the laundry is going to be relocated to the second floor.

 

[Sho'Nuff]

Why did you insulate the basement? That's a big mistake.

If you didn't do that, your basement would've maintained a perfect temperature all year round (ok fine, you would need some heat).

In MOST of the cases, insulating basement walls = no no

Care to explain why insulating a basement is bad? Code in my area requires it when refinishing a basement, so not sure I could have avoided it even if I wanted to.

 

[Sho'Nuff]

If he's near a wetland area, the floor slab (and walls) might be letting water vapor in. Otherwise????

My house is in the middle of a wetland, so yeah. Its moist air coming through the slab and walls. contractors told me I couldn't seal the floor because hydraulic pressure etc. might build and eventually crack the slab.

 

[Sho'Nuff]

Sounds like your old basement walls were very leaky, air and/or water vapor, and the insulation now traps everything inside -- why I don't believe in finishing basements.

If you don't want A/C, pop a window?

Also, A/C should do some dehumidifying on its own, but its main goal should be temperature. I've done some reading recently and there are people who run A/C + dehumidifier.

Its not that I don't want AC. I just want to see if I can get away without it. Opening the window would be futile as it is 90+ degrees outside right now with relative humidity somewhere around 75%.

I think putting in a ducted humidifier might do the trick. I can dump the dry warmer air in my utility room, where it will be sucked in by my heat pump hot water heater (which basically has a small AC unit on top of it). Should improve the efficiency of my HWH while offsetting the heat load produced by running the dehumidifier.

Will see how it goes in a few days. The contractors are taking FOREVER to finish installing the hot water heater. Its been over a week already and I noticed the other day that they did not follow the instructions and maintain a 2' clearance around all sides of the unit (important in this type of HWH), so they have to drain it, disconnect it, move it, and reconnect it again.

 

[ElFenix]

why would you need the dehumidifier after you install an A/C?

 

[Sho'Nuff]

I would not run a dehumidifier when a a very small AC unit will both cool and dry out the basement.

You do not need to size AC units (or heating) the same way you do normal living spaces because the load is usually much lower assuming your mostly underground.

You can probably get a unit rated at half the recommended sq ft and it would do the job fine.

Not sure if a small AC alone would do the trick in my case. Particularly as I need to dehumidify all the time.

 

[Sho'Nuff]

why would you need the dehumidifier after you install an A/C?

See post 21

 

[vi edit]

Do you have electric water heating, and is it in the basement? If so you could look into those hybrid water heaters that effectively are heat pumps.

The suck up the heat in the surrounding area, condition it, and then use that to help heat up the water in addition to electric elements in the tank. They'll lower the ambient temp, condition the air, and reduce your electric bill for your water heating needs.

 

[Juddog]

Start with a dehumidifier.

Knowing that the A/C removes humidity, he probably wants to put it in the same room to let the two machine duke it out.

 

[Juddog]

Its not that I don't want AC. I just want to see if I can get away without it. Opening the window would be futile as it is 90+ degrees outside right now with relative humidity somewhere around 75%.

I think putting in a ducted humidifier might do the trick. I can dump the dry warmer air in my utility room, where it will be sucked in by my heat pump hot water heater (which basically has a small AC unit on top of it). Should improve the efficiency of my HWH while offsetting the heat load produced by running the dehumidifier.

Will see how it goes in a few days. The contractors are taking FOREVER to finish installing the hot water heater. Its been over a week already and I noticed the other day that they did not follow the instructions and maintain a 2' clearance around all sides of the unit (important in this type of HWH), so they have to drain it, disconnect it, move it, and reconnect it again.

I'm not sure if a ducted humidifier would increase the humidity that much better than a plain ol' humidifier would.