How do you calculate fan CFM for AC box

[ureapwhatusow]

anybody?

 

[green_tea]

after having built one myself, I can tell you that the inline fans they sell at the home depot or whatnot don't help that much...

I can also tell you that unless you are running it more than say 10 / 15 ft, the blower in there should be plenty, AS LONG as you are using a large enough vent system. Id actually recommend you to use the square vent ducting, you can make it more rectangle, and save some space that way.

I have a 5k BTU AC in a box, with 8" diameter flex tubing going about 4 ft (this 4ft run is the intake)

then it has about a 10ft 8" run of flex tubing going to wherever (attic / house in winter)

I put temp sensors in the intake side of the box, and the exhaust side of the box, and the exhaust will usually be about 40degrees warmer than the intake air. (Haven't seen intake air hit 90 yet, so that keeps me under my personal comfort zone of 130 exhaust temp.

I think i did the calculations in a separate thread, and came up with something like 250CFM per 5000BTU's Of course its probably not a straight line increase.

 

[Whatever]

Please describe your setup as just wanna make sure. Are you talking about running an AC in an enclosed space (not hanging it out a window) and wanna keep it cool and vent the heat?

 

[green_tea]

yeah.

I built a box... the entire AC is in the box... there is a middle divider that separates the exhaust radiator side from the intake side... fully sealed with silicone sealant.

I rigged the AC unit itself with some tubing for condensation, along with waterproofing the entire middle section of the box. in the middle section that's waterproofed, i also added a drain just in case.

i basically separated the hot rad and cold rad from each other... and I also took apart the AC to seal it better.


I then have 8" ducting for each section... air comes in from window cover, goes about 3 feet of ducting to the intake section.

then it goes through ac unit, and then goes through the exhaust ducting attached to the back section, also 8" (may be a tad small for it)

this then runs maybe 10 ft to where i exhaust it.