Is it worth using a dehumidifier to help cool house?

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Our A/C seems to struggle to cool off our house, especially in the summer. I am not sure what size the unit is, but I do know the condenser was replaced after 2013. I am looking into purchasing a dehumidifier to remove excess moisture from the house. I am borrowing my mother in law's unit for a week or so to see if it helps. Do any of you use one of these to help remove excess moisture and make your house more comfortable? Also, I will be checking my energy use to see if it will reduce our bill.
 
Get your house AC tuned up better. Dehumidifiers leave you with warm air and a bucket of water.
 
Originally Posted by eljefino
Get your house AC tuned up better. Dehumidifiers leave you with warm air and a bucket of water.


Some of the older less efficient AC units are just as capable of dehumidifying as an actual dehumidifier.

A dehumidifier makes about 300-500% more heat than it uses in Watts so expect things to get toasty,
Dehumidifiers are great in the winter and perfect if you have a floor drain and lots of vacation to stay out of the house.
 
How's the duct work and insulation?

In a humid environment like FL, a dehumidifier isn't a bad idea. Do you have a hygrometer to see if it's needed?
 
Originally Posted by dishdude
How's the duct work and insulation?

In a humid environment like FL, a dehumidifier isn't a bad idea. Do you have a hygrometer to see if it's needed?


We live in a 1959 home, ductwork is original as far as I know and insulation is only blown in in the attic.
 
Originally Posted by gregk24
Originally Posted by dishdude
How's the duct work and insulation?

In a humid environment like FL, a dehumidifier isn't a bad idea. Do you have a hygrometer to see if it's needed?


We live in a 1959 home, ductwork is original as far as I know and insulation is only blown in in the attic.


For the duct work you can see, is it sealed with mastic? is the insulation deep enough? How's ventilation in the attic? A fan up there might be a consideration.
 
Try to gather some numbers.

Outside temp, inside temp set to, actual temp inside house at hottest part of day, humidity *(in and out), etc. Then put your thermometer for an hour or so in each room, any rooms warmer than others?
 
Originally Posted by Alfred_B
I would use a portable AC for additional cooling. Some have a dry function as well.

Portables in my opinion won't help. All that hot air that the portables blow outside is replaced with outside air being drawn back into the house or you would wind up with a vacuum. They in my situation raise the humidity in the house, and I verify that with a hygrometer. If the condenser is too big, it may short cycle, and not run long enough to remove the humidity. If too small, it can't remove enough humidity no matter how long it cycles. I'm no HVAC pro, but maybe someone with more know-how can chime in.
 
I use damp rid around my older house in Florida during summer.
 
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We have a vacation condo up in the mountains and externally visible AC units are not allowed, so on the occasional warm day we just run a dehumidifier in the place and it helps a lot.
The place was just a little toasty and close last time we went up there and it was quite comfortable after the dehumidifier had run for about an hour.
 
A dehumidifier will never cool a house. It will always add heat. But it will make it more comfortable by reducing humidity.
 
I would see if your gas or electric provider offers a free energy audit Many offer a free one.
Your home was built in 1959 when builders didn't care much about insulating as utilities were cheap.
There might be a tax credit if you have any work done.

You can rent a machine to blow it in from Home Depot... Make sure it's done correctly as you don't wanna cutoff air flow from any soffit vents.
 
How does the A/C struggle? Does it run all the time? Cycle often?

Ideally, you want your A/C to cycle about twice per hour. You want it to run a long time, as that is when it starts removing humidity. If it cycles too often, the evaporator just gets cold enough to eliminate humidity when it shuts off... Which takes between 5-10min if I recall to reach the point in which it will take humidity out of the air.

Just playing around with my thermostat "swing" setting, I can see a change in humidity levels. If you set at 72 with a 1/4 degree swing, it will turn on at 72.25 degree and shut off at 71.75 degree. With that setting, my house was mid 50's relative humidity. Increase it to ½ degree swing (on 72.5, off 71.5) I was around 48-50%. I found the sweet spot at .75 degree swing, in which my RH levels are around 45-48%. The house feels even cooler now with more humidity out.

We have window people coming today to plan on replacing our upstairs windows which are completely shot, so that should help big time. Upstairs, you can feel the higher humidity due to leaky windows. We already had our lower level windows/doors replaced and that was a big help.

I also run a dehumidifier in the basement during summer, which drains right into the drain, so I never have to empty it. Helps keep the basement around 45% RH.
 
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Originally Posted by xBa380
How does the A/C struggle? Does it run all the time? Cycle often?

It will run constantly. The only time it every reaches the desired temp is in the early hours of the morning after running all night.
 
A dehumidifier is effectively an AC that vents the heat from the cycle in the space it resides. It will raise the temperature of the room.

Whether or not that makes a difference depends upon how humid it is in the space and if the rise in temperature does better or worse than the reduction in humidity.

If you were in a more seasonal climate Id entertain the idea of running a dehumidifier and AC, after all, the AC system is probably good for a few ton, and the dehumidifier wont add more than a ton.

But in FL, I think youd run it too often that way - its not like in the NE where the number of days when it is truly sweltering is maybe 5.

I think you need to clean coils, verify charge, and look into multi-stage compressors so that you can get it to run long-term for dehumidification.
 
If the system is running all the time, then it should have plenty of time to remove humidity, unless the evaporator coil is not as cold as it should be.

What is the vent temperature? How about the duckting near the evaporator? It can be easily measured with an infrared thermometer. I remember in my previous house, the main duct right above the evaporator would have a bit of condensation on it when ac was running during humid days.

Also, what is the desired temp selected? If it's something like 70 or below, then even new systems may run all the time, as they are usually sized for 75F.
 
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I used one for a month down at my coastal camp - after seeing the electric bill - went back to buying DampRid clones at the dollar store.
 
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