AC Swapped Out

[markp1988]

I'm not trying to hijack the thread but have a question? I want to do something similar but do not want to cut holes in the walls. Is it possible to vent the exhaust through the floor instead?

[jwh92020]

Martin,
Thanks for the info. The exhaust itself measured 18 x 13 (234 sq.in.) Unit is 20x 15. I can open up side intakes to 22 x 6 (132 sq. in.) That would be 264 sq. in. I'll do that in the am.

[jwh92020]

Mark -
You could vent thru the floor. I wanted to, but there was a lot of frame where mine would have vented and I was afraid it would be restricted too much.

[m.colley]

I'm not trying to hijack the thread but have a question? I want to do something similar but do not want to cut holes in the walls. Is it possible to vent the exhaust through the floor instead?

You can BUT you results may be less than optimal due to the heat from the exhaust wanting to rise. That rise is hard to overcome without help. A couple of computer case fans may be needed.


Martin

[m.colley]

Martin,
Thanks for the info. The exhaust itself measured 18 x 13 (234 sq.in.) Unit is 20x 15. I can open up side intakes to 22 x 6 (132 sq. in.) That would be 264 sq. in. I'll do that in the am.

jwh,
Your more than welcome. Increasing the hole sizes will definitely help. I believe you'll find your unit will run completely different. Its hard to cool/remove heat from the inner air without the ability to exhaust/exchange the heat removed in the process. That is the main reason you portable didn't work the way you wanted it to.


Martin

[jwh92020]

The portable was a dual hose unit, so in theory it should have performed better. The biggest issue I had with it was the volume of air it moved was minute compared to the window unit.

[working on it]

your two 5" holes on each side may not be large enough. Here's why I say this. On my 8000btu unit I have two side intake louvers and one intake louver on the top. The side intakes measure 5x11 inches which equals 55 sq inches, the top measures 4x11=44 sq inches. 55+55+44= 154 sq inches. A 5" round hole equals (radius x radius x3.14) 19.6 sq inches x 2= 39.25 sq inches. By only having the two 5" holes on each side I would be shorting the ac unit my top vent equivalent (44 sq in) as well as the 15.75 sq in difference from the side vents. This will affect the way your AC performs.
The AC manufacturers size the intake louvers to equal the rear exhaust opening size.

You might want to measure your louver openings and see how yours size up to compare to my example.


Martin

• In my two previous posts in this thread, I suggested using either a case fan, or a duct fan to increase the airflow in through one of your 5" holes, and out the bottom exit 5" hole, just to ensure fresher air from the outside gets forcibly moved into and around the chassis. The rear exhaust exit doesn't need help, as long as hot air doesn't build up in the styrofoam enclosure; the extra fan is only suggested to prevent the build-up of hot air inside the enclosure (where two sets of louvers have no free ambient air source), and, being outside the chassis itself, the hot air isn't subject to the direct action of the exhaust fan, so another fan can help remove it.
• I used a case fan to move ambient air thru the chassis,; it wasn't a powerful fan, just something to move the air quicker, The chassis enclosure is much larger than yours, because it is my whole galley (when the hatch is closed), and the great outdoors (when opened). The side wall vent is always open, and lets fresh air in, always. My exhaust is sent into a large plenum, turned 90 degrees, then ejected with the help of a 240 cfm fan inside the duct, thru an open 6" hole in the right side wall. No "exhaust" air contaminates the "fresh" air intake of the chassis.

• 

  CORSAIR SP-120 cfm.png (199.26 KiB) Viewed 2274 times

  case fan with similar specs was used to move ambient intake air

• 

  Aero-flo 6 inch-diameter duct fan for exhaust work.png (303.45 KiB) Viewed 2274 times

  exhaust ducting was aided by this 6" fan
• I didn't use a case fan near the actual exhaust, fearing that the heat would damage it, and that the cfm wasn't high enough to quickly eject the heated air. I preferred the in-line axial duct fan, for those reasons. However, it is noisy, and becomes quiet enough to use, only because it is completely wrapped inside the fiberglass and foil ducting.

[jwh92020]

working on it -

I didn't discount your suggestion about the fan, in fact I ordered 2. It seems that if I have room to open the intake area, it certainly couldn't hurt. That, in conjunction with using a fan should increase intake air flow substantially. Since the fans are small and inexpensive, I figured 2 on one side blowing out (On the side of the ac toward the rear on the trailer) would be a good thing.

[jwh92020]

I put a $3 deflector on the unit to aim the air upward. It made a big difference, but there was still cool air near the floor. I also made larger duct out of foam board, but I don't think it improved the air movement enough to justify the ugly of something like it. I opened the bathroom door and set a fan in front of it to draw warm air from the bathroom. I set the ac at 75, the warm air coming out registered 82 on the ac, then that # began to drop. Before long, there was very cool air blowing about the trailer. I laid on the bed and could feel the cold air falling from the ceiling. Inside temp dropped to 75 fairly quickly (outside was 85). I can sleep in 75 degree air no problem. Now I have to figure out how to make this deflector idea look better and move the warm air from the rear of the trailer to the front so the thermostat sensor feels warm air unilt the entire trailer is cooled.

Deflector

"Duct"

Drawing Air from Bathroom

View From Rear Of Trailer

[flboy]

Glad to hear that worked for you. I am sure just having another fan down low to stir the air up helped alot.

Sent from my SM-G935P using Tapatalk

[jwh92020]

Don -
Pulling the air from the bathroom made the most difference. Feeding warm air to the room intake seemed to make the unit happy. McDave suggested a floor to ceiling duct with a draw fan to pull the warm air to the front and feed it down to the floor. I'm waiting to see what his idea actually entails.I'm not sure if the draw fan and the fan mounted on the side of the cabinet will cancel out each other's effectiveness. I did open up the fresh air intakes, and I have 2 case fans coming to set inside the plenum. It certainly can't hurt to move as much air as possible through those intakes.

[flboy]

The fans for the intake (condenser fan intake is what I mean here and not the evaporator fan intake) will help if you think the AC is not getting enough air and therefore not working efficiently. Just mixing the air inside so the thermostat doesn't shut off prematurely due to colder air near the floor is a separate issue. In any case, for the thermostat issue, I think your interior fan as you have it is a simple way to mix the air, but pulling from the ceiling would be best. The floor to ceiling duct idea is interesting and certainly a more controlled way to mix the air as intended. There are ways to electrically convert your system to work with a house type thermostat you can put higher on the wall, but that would be an involved electrical mod. I'd probably try that first in my situation, just because I like to do that sort of stuff. Probably not for someone not familiar with reading schematics, soldering, and etc..

Sounds like you are on the way. :-)

Sent from my SM-G935P using Tapatalk

[jwh92020]

Don,
Appreciate the the help. As for soldering and all that - not me, I can burn a board real easy! 2 case fans cost me $20. I figure the $20 is a small investment to maximize the air flow to the intakes. I like the idea of the fan down low, coupled with pulling warm out of the bathroom. I had a thought about putting a small draw fan in the wall to the right of the bathroom door at floor level and a push fan to the left of the door which would push the air right at the room intake. i would then put a small fan on the floor under the bed pushing air toward the front of the trailer. The fan on the cabinet pushes cooled air across the ceiling which should push the warmer air down when it hits the rear doors. The fan under the bed would push that warm air to the front and the fans in the front wall would move it thru the bathroom and toward the ac room intake. in theory (at least in my cabinet makers mind) this would move warm air from the sleeping area and help cool the bathroom by pulling air from it as well. Thoughts?