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Venting portable AC into attic to connect to bathroom vent to outside

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honcho

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Near Sodom & Gommorah (aka Wash. DC)
One room of house on 2nd floor, southwest corner has around 75 sf of glass and lots of solar gain. Even with solar film and thick curtains, the room is too warm, especially when it's sunny. Would like to spot cool the room. A minisplit would probably be the best option, although it would require the most work. Considering a portable AC unit but have the challenge of venting. The largest glass area is a sliding patio style glass door about 9'x7'. There are kits to allow the door to be used as the vent but that would probably draw the ire of HOA dragons who already complain about the solar film. Alternately, thinking about the possibility of venting the portable AC into the attic and connecting to the nearby bathroom exhaust vent line. I'm thinking that an inline booster fan with some sort of switch, either automatic or manual, will be necessary to get adequate air flow.

Anybody have any experience doing something similar to this? Any pitfalls I should be aware of before I get on a ladder and start cutting a hole in the drywall ceiling?

thank you for your help.
 
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Ohmthis

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I don’t think you will get what you want this way. The vent will most likely be 4” and you will need substantially more flow. Another issue that I’ve seen with the portable units, they put your enclosure in a negative pressure situation. It can **** through seals, cracks, and vents.
 
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PoorUB

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honcho said:
One room of house on 2nd floor, southwest corner has around 75 sf of glass and lots of solar gain. Even with solar film and thick curtains, the room is too warm, especially when it's sunny. Would like to spot cool the room. A minisplit would probably be the best option, although it would require the most work. Considering a portable AC unit but have the challenge of venting. The largest glass area is a sliding patio style glass door about 9'x7'. There are kits to allow the door to be used as the vent but that would probably draw the ire of HOA dragons who already complain about the solar film. Alternately, thinking about the possibility of venting the portable AC into the attic and connecting to the nearby bathroom exhaust vent line. I'm thinking that an inline booster fan with some sort of switch, either automatic or manual, will be necessary to get adequate air flow.

Anybody have any experience doing something similar to this? Any pitfalls I should be aware of before I get on a ladder and start cutting a hole in the drywall ceiling?

thank you for your help.
Click to expand...
No double hung or slider window to dump it out? I realize the HOA would probably frown on it, but a bit of flat black paint to camouflage it and they might not notice.

I also agree with the previews post. Portable AC units are terribly inefficient and exhaust a fair amount of air from the home, unless you find a two hose unit.
 
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mm08822

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What about using a bathroom exhaust fan mounted in hallway(?) ceiling to pull cooler air from that area and exhaust it into the bathroom. Locate the (vent outlet of the fan) inlet in the bathroom ceiling closest to the windows so it can push the most warmer air out into adjacent room. Use insulated duct to minimize condensation. Use a t-stat located in bathroom to run fan.
 
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H

honcho

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Near Sodom & Gommorah (aka Wash. DC)
PoorUB said:
No double hung or slider window to dump it out? I realize the HOA would probably frown on it, but a bit of flat black paint to camouflage it and they might not notice.

I also agree with the previews post. Portable AC units are terribly inefficient and exhaust a fair amount of air from the home, unless you find a two hose unit.
Click to expand...
As mentioned, there is a sliding glass patio style door. The other tall skinny window is fixed in place. Contemporary style townhouse.

This room is an outlier because of it's position. 20 years ago it was better because there was a large tree outside but it died and the replacement tree is taking it's sweet time to grow.
 
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CoogarXR

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Ohio
I know for sure that you can't step-down or obstruct the exhaust hose on a portable AC or it will overheat.

Back when I worked for a place that recycled electronics, we would buy store returns in bulk. One year we got a bunch of working portable AC units with no hose kits (****** people buy them in the spring and return them in the fall, sans accessories, of course, but that's a whole 'nother topic...).

My boss decided to try reducing the fitting to 4" and using standard dryer hose to vent the exhaust, and overheated every unit we tried it on, lol. And it wasn't an easy repair either; it was the thermal overload soldered inside the bottom of the exhaust blower motor windings. HUGE pain in the *** to replace.

So yeah, don't get too creative with the exhaust, lol.
 
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Blue

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Northern Illinois
honcho said:
A minisplit would probably be the best option, although it would require the most work.
Click to expand...

honcho said:
.....Venting the portable AC into the attic and connecting to the nearby bathroom exhaust vent line. I'm thinking that an inline booster fan with some sort of switch, either automatic or manual, will be necessary to get adequate air flow.

.......get on a ladder and start cutting a hole in the drywall ceiling?
Click to expand...

Given all of the work to make the portable AC viable, I feel like the minisplit might still be the easiest option.
 
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American Locomotive

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Don't know how hot it gets in your area, but generally speaking if it's much above 90°F, a single-hose portable air conditioner exhausting outside will likely make the room hotter. Every cubic foot of air that goes out that hose needs to get replaced from somewhere. The only place that can be is outside, so you will be drawing in tons of 90°F humid air back into the house.
 
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