AC Swapped Out

[jwh92020]

So I found out that my 12k portable ac was not going to cut it when it came to cooling my CTC. With help from a lot of you, I tried to make what I had work, but it just didn't. I picked up a new in box 10k window unit for $150. Seemed like a good deal. The only place to mount it was on the floor of the cabinet the portable was in (without tearing apart a trailer that is basically done). I wanted to exhaust thru the floor, but there is too much frame work in the area and I was afraid it would restrict air flow. I cut an opening in the side of the trailer for the exhaust. I already had 2 - 5" holes for my portable's ducting on the right side of the opening, so I mirrored them on the left. I tested the draw with a smoke stick after I enclosed the intakes and there was a healthy draw. The exhaust duct is 1" foam board taped on the outside and caulked/taped on the inside of the joints. The top of the intake box sits on cleats attached to the side & rear wall. Thais will allow me to put a pice of 1/4" ply on it and use the area above the ac for storage. I still need to do the whole "make it look nice" thing, but it blows some cold air. I am having an issue with the cool air fooling the thermostat, so I need to come up with a deflector idea or a duct idea that doesn't look terrible to get the cold air up toward the ceiling. I may need to put some type of power vent in the rear of the trailer to help draw air that direction. thanks for all your help. Any ideas on moving the thermostat sensor, deflector or duct ideas will be appreciated.

Exhaust Duct In Place

Intake Holes

Unit Boxed In

Exhaust Vent Painted (White wasn't going to work for me)

Deflector Idea

[working on it]

• Your foam/tape enclosure looks to be a trap for warm air around the chassis coils; you need some airflow over and thru the chassis vents to assure the equipment doesn't overheat, and shut down. The heat rising from the top vents will just build up, without good ambient, or forced, airflow. I would suggest using a fan (a computer case fan, or a duct fan, blowing out, mounted over one of the two downward facing holes you already have cut, and a screen over the other (to keep insects and debris from entering ); that way, you'll have a constant change of air flowing thru the sealed enclosure.
• Your exhaust looks like it will work great, as long as nothing obstructs the louvers, so leave some room next to your trailer, when parked. And, to direct your cold-air output upwards, may I suggest what I used to deflect my A/C air:

• 

  Frost King air deflector.PNG (130.93 KiB) Viewed 2902 times

  adjustable for width, with magnetic strips (I used foil tape, instead)
• I bought mine at Home Depot, to aim my cold air further forward, along the underside of my un-insulated roof, to cool it before my air circulator fan returns the airflow towards the rear bulkhead.

• 

  air deflector taped on unit.png (482.71 KiB) Viewed 2902 times

  I used foil tape; white or gray would've blended in better

• 

  air circulator returns air to the rear wall.png (581.46 KiB) Viewed 2902 times

  cold air deflects off the sloped front & returns rearward via air circulator fan

[jwh92020]

working on it - Is the vent on the top of the ac to exhaust hot air from the coils after it is drawn in through the side intakes? I have 2 - 5" holes on each side of the ac unit thru the floor. Should I mount a fan on one side of the unit and place filters over the holes on the other side? Will the fan provide sufficient air flow, or should/could I an opening in the top of the enclosure and loop a hose into the top of the exhaust duct, or run the hose to a small vent thru the sidewall. I'll try to track down a deflector like yours. than you for the help.

[working on it]

working on it - Is the vent on the top of the ac to exhaust hot air from the coils after it is drawn in through the side intakes? I have 2 - 5" holes on each side of the ac unit thru the floor. Should I mount a fan on one side of the unit and place filters over the holes on the other side? Will the fan provide sufficient air flow, or should/could I an opening in the top of the enclosure and loop a hose into the top of the exhaust duct, or run the hose to a small vent thru the sidewall. I'll try to track down a deflector like yours. thank you for the help.

• Hot air rises, so the top louvers should never be blocked; usually, ambient air flow, will move the hot air up and out of the top vents, conducting air over the coils in the chassis naturally, with help from the blower inside the unit (which also expels the hottest air flowing over the coils). I think that you should first try it with just a fan on one of the holes, and a screen on the other, but it may work just with the main exhaust fan, alone. I didn't want to chance it on mine, having fought with thermal shutdown before I got it right, so I furnished an ambient air supply, and a fan to draw air over the chassis, to help the sealed exhaust.

• 

  ac chassis cooling set up.png (529.53 KiB) Viewed 2864 times

  since I had the space, I added a case fan to help cool the coils

• 

  asv-window-unit-ac.jpg (98.42 KiB) Viewed 2864 times

  air drawn in the sides (and top) is mainly expelled thru the rear (unless trapped)
• Since your set-up has a straight out the back exhaust, you may not need the extra fan, but the holes should be screened anyway, so insects and critters don't enter your sealed box. I have an open exhaust duct, but it has a 240cfm steel-bladed fan inside, to make short work of them. The side vents are inside my galley, which is closed when I usually run it (at night),or during the day, opened shortly, when using items in the galley; that's why I have exhaust ducting to the side, instead of straight out the back, thru the hatch.

[jwh92020]

I just raised the top of the enclosure 3", which gives me 6" above the unit. I'm having an issue finding a fan that will fit along side the unit. The holes are 5" but the unit covers them on each side by about 1/2". I looked at Amazon and the fans themselves would fit, but not in the cases. Do you think I could get away ith mounting a fan at the top of the unit pulling air up and over the unit? BTW - thanks for your help. I really do appreciate it.

[Padilen]

Is all that needed?
Don's seems to work well. But he does have a top exhaust. Im may be going in this direction soon. So I'll keep my I on this.


Sent from my iPhone using Tapatalk

[jwh92020]

Padilen -
If I could have mounted it up high, I would have. That would have entailed tearing out a finished wall, cabinets, re-routing electrical, cutting an exterior wall (which I did) and a hole in the roof, and that just didn't seem like something I wanted to do. As for the fans for the intake, I used one on a vintage rehab that I did and it really did help the ac perform better. I have decent intake flow, but if a $20 fan makes it better, I'll spend the $20. Now it's a case of figuring out how to move the air up and to the rear of the trailer where the bed is. Even with a temporary deflector and a fan, I got the interior temp to 80. Outside right now is 95 with a feels like of 105. with the portable, it would have been well over 90, so already there has been a big improvement. I just found a roof vent (like a Fantastic Fan) with a 110v motor. I only have 12v for my lights because I use his trailer for work, so I will always be at a place with shore power. i'm thinking that vent may be the answer.

[Padilen]

I wasn't suggesting mounting it up higher. I just wanted to know if that's why his seems to work well.
I can't get mine up high either. Well, can't is a strong word. But I can get mine to about 3' possibly a little more. That's the top of the AC unit not the bottom.
For a fan have you seen the inline duct booster fans? I have a 6" but I believe they come in 4" too.


Sent from my iPhone using Tapatalk

[jwh92020]

I'm sure Don's unit works really well because, well Don is Don. Just look at his build. I've been looking at the inline booster fans. I'm trying to figure out how to come off the front of the unit, transition into ducting sing a fan and not have it look like an abomination. Once I get the duct to the wall, I can box it in and make the look good. Or go rustic industrial and run a duct down the center of the ceiling a have a couple of drops. Not sure if that would entail 1 inline fan or multiple units.

[Padilen]

Don is Don can I quote that!. I'm not sure about cfm's that's why I PM'd McDave.
I did try to get ducting to make my portable a 2 hose. I bought all the wrong stuff had a big brain fart at that time ! But like you I'm thinking window unit. Got a few ideas all involve compromising.
But I'm not budging on no roof top changes- additions that add height. No cutting "studs".



Sent from my iPhone using Tapatalk

[jwh92020]

That was my thing. Roof wasn't set up for ac, didn't want to cut any studs. I pm'd McDave as well. Lets see what he comes up with.

[Padilen]

The roof thing I think people don't understand what "set up for AC is". You can pull out a ceiling fan and install AC. My reasoning is my CTC still can fit in my polebarn. Axle flip made swapping wheels necessary & it just squeaks in.


Sent from my iPhone using Tapatalk

[linuxmanxxx]

You have to build a plenum that divides the rear outlet from the side intakes. If your rounds intakes provide enough air it will work without forcing anything. If it doesn't just go to a larger rectangle intake. Just be sure the plenum is as far back as possible so you have the largest area for fresh air to feed the condenser fan side. Then you should see it work much more efficient.

Sent from my Nexus 6P using Tapatalk

[jwh92020]

linuxxman -

I have an exhaust duct that surrounds the ac case and separates the exhaust from the intake. The rear of the unit is 4.5" from the wall of the trailer. I made th exhaust duct 5.5" wide so that it covers 1" of the case at the rear and it is firmly against the outside wall. The exterior seams are foil taped and the interior joints are sealed with high temp silicone and foil tape. Where the duct meets the wall is also siliconed and taped. The intake box is formed by the cabinet walls that had the joint where they meet the floor siliconed, the floor itself and the top is a 1" piece of double foil faced foam board. There is 6" between the bottom of the top of the ac and the top of the intake box. The box top rests on wooden cleats that run across the sidewall and from front to back on each side. the joints are foil taped for now until I am sure I won't need to remove the top again. At that point, I'll silicone the cleats and top edge of the front, reset the top and tape the joints.

[m.colley]

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