How do I quietly reduce humidity in a room?

[mef1975]

What components, or devices, could I use to bring 75 degree air down to 35 degrees within a square foot, keeping in mind, the air will flow thru, probably only a little faster than you would notice coming out of your AC vent.


So, I've sent out the following message to like 5 different AC people, and I'm just not hearing a real solution coming out of their mouths (a couple of them didn't even seem to understand what creates the dew point), and I'm afraid to let anyone do any work, particularly after my experience going thru 5 plumbers just to set up an RO system properly (I may be ignorant, but when I can open a manual and see content printed in BOLD and ALL CAPS proving that the job is not being done right, I just hate having to argue, as if my insisting that copper tubing be replaced with polyethylene is wrong, and then, for me to be the one that has to figure out that a DI stage is needed to finish removing the ammonia, I'm suppose to be the customer, not the expert, but yeah)...

Hey, I have a room, probably like 11.5' x 18', with a 6' wide bathroom connected, so more like 11.5' x 24'. We had a 1 ton split Mitsubishi unit put in, and I really do love how quiet and cold it is, but it has made the humidity worse. I keep the room at 70 degrees, the rest of the house at 75. The humidity in the room is typically around 70%, and the house, 60%. Dry mode on the Mitsubishi makes the room 65 degrees, and does little to reduce humidity (probably because it's slightly over-sized). A portable dehumidifier helps after an hour or so, but it is extremely loud, and the humidity returns to where it was soon after it is shut off. Shutting off the Mitsubishi and opening the bedroom door matches humidity to the rest of the house, but here's the thing, I want the door shut, room colder and dryer than the rest of the house, quietly! They say, the 3/4 ton unit would work better, but probably still not as good as I'd like. I really need some way to reduce humidity, quietly, like hunting for rabbits quiet. No, I don't think there's any addict space above the room, maybe some can be made, if needed.

Anyhow, being that nobody has provided a real solution to my problem, I can't help but want to tackle it on my own, so first, after having learned what creates the dew point, I ask, what components, or devices, could I use to bring 75 degree air down to 35 degrees within a square foot, keeping in mind, the air will flow thru, probably only a little faster than you would notice coming out of your AC vent.

 

[tys90]

There are small dehumidifiers that can be ducted. Do you have a room near by with a floor drain? Basement or utility room? You could install one there and duct it to your bathroom. Probably won't be cheap and is overkill for a space that small but that should significantly reduce the sound in the bathroom.

 

[lukaiENG]

I think you need to explain what you are using the room for.
I assume the source of the humidity is environmental (do you live in a humid climate?)

Why are you trying to cool it to 35 degF? that is refrigerator temperatures. I assume it a small air stream that you are trying to cool to this temperature rather than the space as a whole. Assuming you could achieve a space dew point around 35 degF while maintaining your space at your noted 70, this equates to a ~25-30% RH which seems crazy for a home.

If you want to drop the relative humidity of the space, you are better off heating it rather than cooling it. increasing the space temperature from 75 to 80 would drop the RH to 50%.

If your aim is to decrease space moisture content without cooling the room noticeably, you have to cool/dehumidify and heat at the same time. portable dehumidifiers will do this. as the previous poster noted, you could get a ducted one and locate it somewhere less noise sensitive.

With a little more explanation of what your trying to achieve we might be able to give you better advice.

 

[1gibson]

So what happens if you put a quiet space heater in the room, to make the AC work harder? Yes it seems silly, but is it really going to use more energy than adding a separate dehumidifier? Cheap to test at least.

 

[RandomUserName]

Haha 1gibson; the goold 'old "false load" trick!

 

[EnergyProfessional]

Several problems:
1. you need to look at psychrometrics and refer to absolute moisture in air. Relative humidity (RH) will change with temperature without any water added or removed. so your 65°F room may have the same moisture as your 75°f room even if the RH is different. Grains of water per pound of air, or g/kg etc.
2. if you use a 1-ton unit for a small room you never dehumidify... way oversize unless you have a server farm in there. It will cool too fast, before it dehumdifies.
3. need more information here

 

[urgross]

A residential dessicant dehumidifier may do the trick. They work well at lower temperatures, and can be bought with a pump at a reasonable cost.

 

[Drazen]

that's more the question for refrigeration forum, not hvac forum. keep in mind that you will have to wrap the room with insulation sandwich panels (like in cold room for food industry) to have it working.

and yes, buy cold room safety working clothes if you don't want to destroy your health quickly.