Is it possible to make my bedroom 60 degrees?


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Old 06-21-21, 01:43 PM
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Is it possible to make my bedroom 60 degrees?

Hi, I live in Florida and though I love the daytime heat, am most comfortable sleeping in a room that is very cold. In the winter I keep the bedroom at about 61-62 using a Whynter ARC-14S 14,000 BTU Dual Hose Portable A/C but now in the summer it can only get the room down to about 67 degrees. The room is sealed up very well, is 18'x18' with a 9 foot ceiling. I miss having it colder. Will upgrading to a window unit allow me to get it colder or am I stuck because its so hot outside? It was 85 at midnight last night, lol. Also would appreciate thoughts on what size A/C to get. I understand you don't want one that is *too* big because its overkill, but am willing to get whatever will minimize my bedroom temp. Thanks!
 
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Old 06-21-21, 01:50 PM
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Bedroom 60 degrees...... maybe.

Room temperature 18 degrees below outside temperature is doing pretty good...... especially for a portable A/C.

Yes a window A/C will do slightly better and should be able to yield at least 20 degrees below outside temperature.

An 18' x 18' room would probably require a 10k unit. I'd suggest 12k at a minimum.
 
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Old 06-21-21, 02:49 PM
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One must be careful doing something like this.
Such a temperature extreme, can cause you to reach dew point within the wall, and develop mold and mildew.
This can happen easier between interior walls, which aren’t insulated.
Most normal homes aren’t built for this kind of thing.
 
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Old 06-21-21, 05:17 PM
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We used a window unit in addition to our central air in our bedroom for several years to keep it cooler than the rest of the house (& also to assist the central unit during the day), so it wouldn't work as hard. We found that IN OUR SITUATION, we easily lowered our energy bills this way as well.

While every situation is a bit different, personally, I'd suggest getting a window unit to assist your central air unit in cooling your bedroom at night while leaving the remainder of the house up to the central unit alone. FYI, close your bedroom door at night to prevent the window unit from trying to cool the hallway etc.

Just my two cents based on my personal experience.
 
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Old 06-22-21, 04:09 AM
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The bedroom's 4 walls, ceiling and floor are all heat sinks. Insulation, or lack of, make a big difference in the loss of cooling in your case. Calculating the size of a window unit without knowing the insulation info is a roll of the dice.
 
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Old 06-22-21, 04:45 AM
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I had a tenant do this. They they started having nuisance GFCI trips and circuit breakers popping. Condensation in the exterior walls was getting into the outlet and switch boxes causing shorts. Most homes are not insulated or vapor sealed to properly maintain that great a temperature difference, especially with Florida's humidity. It can possibly be done but I think it will also cause other problems.
 
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Old 06-22-21, 06:09 AM
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Lots of good info here, thanks to everyone. I definitely want to avoid any condensation so will be flexible on the bedroom temperature so now want to dial into a temperature that is cold but not so cold that it causes condensation and mold problems.

I'm actually currently in a 25 year old condo but am about to move into a new home built in 2021 with the same size bedroom, so let focus on the new house and forget the condo. Its one floor, cement block walls, two double-pane windows. Can't remember the insulation specs but it is advertised as having a HERS rating of 54. The bedroom has two exterior walls, two interior walls, vinyl plank flooring directly on a cement slab. My normal pattern is to keep the whole house at 79 degrees 24/7 and the bedroom in the low 60s if I can but am willing to use a higher temp if needed to avoid issues. Would appreciate any guesses as to what bedroom temp would avoid wall condensation given these factors, and any guesses as to what size BTU wall a/c would be needed to reach that temp. Thanks

Edit: vinyl plank flooring is 6mm and is not directly on the slab, there is a moisture barrier between it and the slab. I do not know the specs of the barrier.
 

Last edited by johnoh; 06-22-21 at 06:53 AM.
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Old 06-22-21, 06:22 AM
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A ceiling fan even in an air conditioned room can make it feel several degrees cooler. It is only necessary to run the fan when the room is occupied, and makes no difference in the actual room temperature.
 
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Old 06-22-21, 06:43 AM
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probably should have mentioned I also use the ceiling fan while sleeping
 
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Old 06-22-21, 06:49 AM
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With that setup, I’d not go any lower then 68-70° for the bedroom. Especially since the rest of the house will be near 80°.
Your asking for condensation issues especially with a slab floor.
 
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Old 06-22-21, 06:57 AM
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I mistakenly said the vinyl plank is directly on the slab, there is actually a moisture barrier between it and the slab. Post #7 is now edited to reflect that.
 
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Old 06-22-21, 09:06 AM
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Unless the room is specially insulated and vapor sealed for what you want I think you will have trouble. Newer construction or not, keeping an interior room at 60f is going to be expensive and problematic. Simply adjusting your sleeping habits would be the least expensive from an energy standpoint and better for the house from condensation.
 
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Old 06-22-21, 10:57 AM
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My original suggestion of 68-70 stands. You’ll have to modify the construction of the home to drop to that low of a room temperature.
 
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Old 06-22-21, 11:04 AM
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Isn't there also the option of at night keeping the house at say 72-74 degrees and the bedroom at 62-64 degrees? Not concerned about cost btw.
 
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Old 06-22-21, 12:42 PM
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I still wouldn’t recommend it. It’s too much of a difference in temperature. Inside and outside, and between rooms. Normal residential construction isn’t meant to achieve high refrigeration temperature. It’s my opinion you’d wind up with growth within the walls.
 
 

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