dehumidifier info needed

We have moved into a brand new house, and I am seeing higher humidity than I would like to see.

I've experimented with running the AC lower than normal to try and bring it down. This is working, but I'm also freezing to death in the meantime.

We normally keep the AC on 78 while home and 85 when away. We also will set it at 80 when we go to bed. Lately, I'm seeing humidity from 60-70% indoors. That's about 20% too high.

I've got a nice place I can put a dehumidifier. It's a countertop in the laundry room. There's a dedicated 110 plug available and a sink to drain the water into. Guess we got lucky on house design.

Anyone got experience with whole-house models? Approximate costs? Energy costs? What type of humidity drop can I expect?

The house is approx 2500 sq ft heated and cooled.

Also, I have been told by some experience hvac guys that slowing down the blower speed on my ac will help lower the humidity as well. Ramifications from this include: some (how much) lower humidity, more (assumption) energy usage, colder (fact) coil temperature (too low and it will freze and damage the compressor...

Suggestions?

My reconmendation is to run your AC colder. I can't imagine running my AC at 78, I would roast!
During the summer days I run my AC at 72 during the day.(and even in just undies and a shirt that can still be hot) and at night 68-69 I run it at about 75 when away just to save on the massive amount of power I would use to cool back down to 72 when I get home. I can usaly keep the humidity around 40-50% anything lower then 35% and I run the humidifier.

78 is cold for me. I actually like 80, but my wife complains.

Turbo, be sure and take into consideration the heat generated by the dehumidifer, it's fairly significant. Ideally, you could use it to help your water heater.

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BIGIRON said:
Turbo, be sure and take into consideration the heat generated by the dehumidifer, it's fairly significant. Ideally, you could use it to help your water heater.

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Yeah.... I'm wondering about that myself.

78-80 F is good for me, I can't imagine 68-72 F, that's freezing temps., I'd have to wear a sweater. /ubbthreads/images/graemlins/smile.gif

Still looking for someone with experience to chime in.....

During more reading, it turns out that my ac is partly to blame. The house is brand new, and the ac is a HIGH efficiency unit. Apparently these units are purposely designed to not lower humidity as much as other units.

I run the Kenmore De-Humidifiers,portable units
I keep my house about 30% humidity they do produce a small amount of heat,I dont run the drain on them I just empty
the holding tank about once every week and a half
These are 5 amp models they have a frost guard built in to them,for the first few days they run hard than it turns on about every 4-6 hours for about 15 mins

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Lasernerd said:
I run the Kenmore De-Humidifiers,portable units
I keep my house about 30% humidity they do produce a small amount of heat,I dont run the drain on them I just empty
the holding tank about once every week and a half
These are 5 amp models they have a frost guard built in to them,for the first few days they run hard than it turns on about every 4-6 hours for about 15 mins

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What kind of outside humidity do you have?

70% to 90+%
When it is raining hard outside they cycle more often
Sometimes static electricity can be a problem,,
But I can breath better no chance of mold anywhere /ubbthreads/images/graemlins/eeew.gif

We keep temp around 80-81, subsequently the a/c system doesn't extract as much mositure as it would if set for lower temps. We use a portable dehumidifer unit periodically, usually when humidity over 60%. I don't try to control the warm, dry exhaust air -- that's part of the process, but I wish there was a way to control or use the heat. The condensate is emptied periodically into a flower bed. BTW - the condensate is "semi'distilled" water -- I use it in car battery, etc. I drain the a/c condensate into garden and flower beds with regular garden hose -- we don't waste water in South Texas.

I don't understand how a "high eff" unit would extract less moisture? Any thoughts?

The air speed over the evaporator coils is high. It cools the air, but the air doesn't stay there long enough for a LOT of condensation to occur.

Apparently, if you tinker with your fan speed you can slow the air down. It stays in contact with the coils longer which gives more time for condensation to happen. This also is supposed to lower the coil temp since less air is passing over it, which helps to extract more moisture. I'm not so sure on the coil temp arguement..... as water vapor condenses it gives off heat of vaporization which would tend to raise the coil temp.

I haven't yet heard of one of those dehumidfiers which works all that well. We have one in the basement which we used to use before we put AC down there. It never seemed to make much difference, and it made the place hotter. What is your goal for removing the humidity? Do you simply want to make where you live more comfortable? If so, the A/C is all you need. It is the combination of heat and humidity which makes you uncomfortable, not either in isolation.

Yes, the A/C will actually dehumidify more (and cool a little less) on the slow speed. This is because less air flow will allow the fins to get colder which in turn will remove more water (the cold side can actually get well below 0°F if the air is completely blocked). Also, less airflow will mean the hot side will get hotter, and combined with the colder cold side temperature that will mean less cooler power. Electrical usage will be the slightly less because the fan draws a little less on slow. The only caveat here is that if the fins get too cold they will freeze up. I've found this generally isn't a problem with nearly all air conditioners until the room temperature gets under at least 63°F, and frequently less (the one in my bedroom won't freeze unless the room is 57°F).

A dehumidifier is essentially an AC which runs completely inside a room. As such, the power it uses goes to heat the room. This will mean your AC will have to work that much harder to keep a comfortable temperature. All things considered, you'll probably accomplish the same result using less electricity by running the AC on low, and using a space heater with a thermostat at the same time if the room gets too cold for you. The salt used to melt snow also dehumidifies. You can put some in containers in places where air will flow over them. Periodically, you'll need to empty the water and dissolved salt.

BTW, keeping your A/C at 78°F or 80°F is what causes the problem. It simply isn't working long enough to significantly dehumidify. That's why I offered my space heater suggestion (because you don't care for lower temps). Alternatively, wear a sweater or something warm and keep the temps no higher than 72°F, and preferably lower. I keep my bedroom at anywhere from 57°F to 64°F. It's much healthier to breath and sleep with cool air. Yes, I sleep under a comforter even in the summer. Other than that, as long as I'm moving, something around 60°F is very comfortable to me, even in a T-shirt. One year I put Christmas lights outside in just a sweater when it was 15°F. I lasted a good hour doing that. I've heard you can actually lengthen your life by living in cooler temperatures. The theory is that your body is slowly cookin itself at 98.6°F, so anything you do to lower that will make you live longer. Actually, normal body temperature for me is around 97°F. I don't know if living in cooler temperatures lowered it, or if I like cooler temps because I was born with it lower. I just know that anything much over 70°F feels hot to me indoors. Outdoors when I'm exercising I like it under 50°F. I hate summers with a passion. The A/C can't replace naturally cool air.

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jtr1962 said:
BTW, keeping your A/C at 78°F or 80°F is what causes the problem. It simply isn't working long enough to significantly dehumidify.

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Even at 74 the humidity doesn't get below about 60%.

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turbodog said:
Even at 74 the humidity doesn't get below about 60%.

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Lower, lower! /ubbthreads/images/graemlins/wink.gif

Seriously, try 68°F and see if it's OK then. I think the high efficiency unit is likely the problem. Those use larger heat exchargers for a given cooling capacity. This means the hot side doen't get as hot and the cold side doesn't get as cold. Hence the problem with lack of dehumidification. I'm not suggesting to replace the unit with a low efficiency one, but if you consider that others in your position might need to combine a dehumidifier when using a low-efficiency unit then they're really not saving the power that they're supposed to.

It just occurred to me that you might be able to get the unit to dehumidify more by putting a layer or two of A/C filter material on the cooling fins. This combined with the lower fan speed might slow the air enough so that the humidity is removed without lowering the temps to values that are uncomfortable to you.

Dude, I think your thermometer is off. At 68, you can see your breath in here.

At that temp, we'd have such high bills I could hire someone to follow me around with a palm-leaf fan.

Here's a comparison of a few dehumidifiers. I'm still skeptical of these things over just using an A/C. All the ones I've seen so far don't seem to make a noticeable difference. They'll run for days even when it's humid and all you'll see is a miniscule amount of water in the tray. I put them in the same category as plug-in air fresheners or toilet bowl deodorizers-ideas which are good in theory but which in practice end up being just another way to part someone from their money.

Maybe I'm being obtuse but I'm just wondering here why do you care about the humidity at all? Just find an A/C setting where you feel comfortable. That's what I do even though my chosen setting might be lower than most peoples. If the A/C doesn't remove enough humidity then lower temps will be comfortable and vice versa. Humidity one way or another shouldn't matter unless you're storing things which require controlled conditions. If you feel hot with the A/C set at 78 then it's because that temperature is too high for the amount of humidity your A/C removes. Yes, you can remove humidity and keep it at 78, or you can lower it and feel just as comfortable at a higher humidity but a lower temp. And if you already feel fine at 78 and whatever humidity, which I think you do because you said you feel too cold when it's set lower, then what is problem? If you succeed in making it less humid at 78 then you'll actually end up feeling cold at that temp. The idea of climate control is to create a comfortable environment. I think the people here need a little more info in order to help you. As I asked earlier, what is your desired humidity range, and why do you need to keep it there? There might be better ways to solve whatever problems the high humidity may be causing than simply lowering it with a dehumidifier (if that would even work).

Cpuple of thoughts:

JTR, they work. Mine will extract 8+ quarts in 24hrs if the ambient humidity is high enough (in addition to the a/c).

If we kept thermostat at 68, our electric bill would be astronomical -- our net cost is about $.13 kwh.

Turbo -- Why not just sell out and move to Phoenix????

BIGIRON same with me!
they work great!

Humidity at 60-70% is getting up into mold-growing range. Also, it may be comfortable most of the time, but when you're moist (shower, coming in from outside,etc) the water takes longer to evaporate off you.