Dehumidification in hot, humid weather

[FlyingScot]

We also have AC and dehumidifier in basement. But even on the hottest days, basement is cool, so we have never run AC.

I would not run AC and dehumidifier simultaneously. I think either alone is sufficient, and as you suggest, it's a huge load on the AC, especially in the attic on a hot day

[loonguy]

We run central air for the entire house and dehumidifier in the basement. We also run ceiling fans in the high ceiling rooms to help circulate the air.

[mswlogo]

If you have water in the insulation in your roof no dehumidifier is gonna get it out. You're gonna have to rip the outside or the inside off and replace the insulation. Or you risk mold. Probably better to do inside because if that's plaster board it might be wet too. Might be just a small section that got wet.

I don't recommend Pro's very often, but I think you should get some opinions. If you did contact a pro they would have probably started drilling holes in the roof and pumping dehumidified air through it. It may have sat too long now for that option to work.

You don't want a new roof and then have to pull it off.

[FlyingScot]

Originally Posted by mswlogo

If you have water in the insulation in your roof no dehumidifier is gonna get it out. You're gonna have to rip the outside or the inside off and replace the insulation. Or you risk mold. Probably better to do inside because if that's plaster board it might be wet too. Might be just a small section that got wet.

I don't recommend Pro's very often, but I think you should get some opinions. If you did contact a pro they would have probably started drilling holes in the roof and pumping dehumidified air through it. It may have sat too long now for that option to work.

You don't want a new roof and then have to pull it off.

Good points. This post also begs the question of soffit and ridge vents--do you have them?

[SailinAway]

Originally Posted by FlyingScot

soffit and ridge vents--do you have them?

Soffits: yes. Gable vents: yes, but partially blocked at one end due to raised ceiling. Ridge vents: not currently. They will be installed with the new roof.

[SailinAway]

Originally Posted by FlyingScot

We also have AC and dehumidifier in basement. But even on the hottest days

I would not run AC and dehumidifier simultaneously. I think either alone is sufficient, and as you suggest, it's a huge load on the AC, especially in the attic on a hot day

The AC cools the upstairs very well, but does not remove enough humidity, hence mold on the window frame around the AC and in the double-pane window next to the AC. I ran the AC on "dry" and the problem seemed to get worse. That's why I'm considering adding a dehumidifier, but I'm concerned about the amount of heat that a dehumidifier introduces.

[John Mercier]

You may want to ask the roofer.
Usually not both ridge vent and gable vents.

[FlyingScot]

Originally Posted by John Mercier

You may want to ask the roofer.
Usually not both ridge vent and gable vents.

Yes--definitely get a pro opinion here. I do not know what mix of vents you need, but without the right airflow, you are unlikely to solve the problem by just adding more machinery

[SailinAway]

Originally Posted by John Mercier

You may want to ask the roofer.
Usually not both ridge vent and gable vents.

Good point, John. I believe I've read that. The house desperately needs ridge vents.

[SailinAway]

Based on advice here I did add a dehumidifier upstairs and on very hot days I run it and the air conditioner at the same time. Electric bill has been very high this summer, but the upstairs is finally livable.

I'm happy with both of these units I bought this year:

Basement: Frigidaire 35 pints. https://www.homedepot.com/p/Frigidai...33W1/312539821

Upstairs: GE 22 pints. https://www.homedepot.com/p/GE-22-pt...22LA/315445853 Pretty noisy, so don't plan on running it in your bedroom at night.

I had to get a lighter unit for upstairs to be able to carry it up the stairs. I assume a basement would be more humid than the upstairs, hence the higher capacity bucket for the basement. I empty each bucket once a day and that seems sufficient to keep the humidity at around 50%.

The biggest concern with these machines is the high number of reviews that say they last only a couple of years.

[mswlogo]

Originally Posted by SailinAway

Based on advice here I did add a dehumidifier upstairs and on very hot days I run it and the air conditioner at the same time. Electric bill has been very high this summer, but the upstairs is finally livable.

I'm happy with both of these units I bought this year:

Basement: Frigidaire 35 pints. https://www.homedepot.com/p/Frigidai...33W1/312539821

Upstairs: GE 22 pints. https://www.homedepot.com/p/GE-22-pt...22LA/315445853 Pretty noisy, so don't plan on running it in your bedroom at night.

I had to get a lighter unit for upstairs to be able to carry it up the stairs. I assume a basement would be more humid than the upstairs, hence the higher capacity bucket for the basement. I empty each bucket once a day and that seems sufficient to keep the humidity at around 50%.

The biggest concern with these machines is the high number of reviews that say they last only a couple of years.

Those reviews are right. Gosh I bought so many of those POS dehumidifiers.
A friend of mine had the same problem and found one of those old ones with the big exposed coil on the back being thrown out. Super inefficient but damn thing keeps running.
I even bought an $800 commercial one and that died too. But they did warranty it and sent a brand new one, I sold it sealed as new.

[TiltonBB]

Originally Posted by SailinAway

I had to get a lighter unit for upstairs to be able to carry it up the stairs. I assume a basement would be more humid than the upstairs, hence the higher capacity bucket for the basement. I empty each bucket once a day and that seems sufficient to keep the humidity at around 50%.

The best solution would be even better if you didn't have to monitor it and dump the bucket. I have seen them connected to drain into a reservoir with a pump and float that will empty automatically. Amazon has one:

https://www.amazon.com/Little-554435...NsaWNrPXRydWU=

I have a friend who hooked up a boat bilge pump in a bucket with a 12 volt battery on a trickle charger to accomplish the same thing.

You only need to run the drain hose outside or into a sink and then you can forget about it. You won't need to empty the bucket again.

[JEEPONLY]

Originally Posted by TiltonBB

The best solution would be even better if you didn't have to monitor it and dump the bucket. I have seen them connected to drain into a reservoir with a pump and float that will empty automatically. Amazon has one:
You only need to run the drain hose outside or into a sink and then you can forget about it. You won't need to empty the bucket again.

I once saw a display where the homeowner pumped the water up from the basement and out to what looked like a pretty sprinkler showering plastic flowers in the side-yard. Pretty clever/cute.

[SailinAway]

Originally Posted by John Mercier

You may want to ask the roofer.
Usually not both ridge vent and gable vents.

"Gable vents work fine by themselves but what we have learned through research is that if you have a proper ridge venting system then you should block off the old gable vents. It turns out they work against one another and pockets of dead air begin to form in areas in the attic and that's not what you want." https://www.capitalgazette.com/busin...626-story.html

I forgot to ask the roofers about this. I will have this taken care of at some point.

[WinnisquamZ]

Originally Posted by SailinAway

"Gable vents work fine by themselves but what we have learned through research is that if you have a proper ridge venting system then you should block off the old gable vents. It turns out they work against one another and pockets of dead air begin to form in areas in the attic and that's not what you want." https://www.capitalgazette.com/busin...626-story.html

I forgot to ask the roofers about this. I will have this taken care of at some point.

True. Was told the same when I had my roof redone in 18.


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[mswlogo]

Originally Posted by John Mercier

You may want to ask the roofer.
Usually not both ridge vent and gable vents.

I think I’ve heard that too. You need flow and if you do both it messes it up.