Explain to me how rooftop A/C removes humidity from inside coach.

[Scott & Heather]

Not sure I understand how this works...does the interior condenser fin thingy condense the water and drip in outside onto the drip pan? From my observation, the interior cooling part is sealed on the inside...with tubes going to the outside through sealed holes on the A/C body....the drippage happens outside...help me guys...I'm HVAC illiterate.

[Utahclaimjumper]

Very simply . hot air will hold MORE moisture than cold, therefor as the air is cooled in the outside condenser the seperated moisture will accumulate in the drip pan and down the side of your coach if not directed elswhere. This is why most rainstormes occur in the late hours when the air is cooled.>>>Dan

[FloridaCliff]

Scott,

Just for you....

How Air Conditioners Work

Cliff

[Scott & Heather]

Thanks Dan and Cliff....I loved the video too....but I'm still not getting how the moisture in the coach physically get's removed or transferred outside...I know a dehumidifier condenses the water onto the coils and drips it into a bucket or a drain hose leading outside...I understand that physical interaction....but a roof air conditioner?  It just cools the air....and as you said, cool air holds less moisture but where does the moisture go?

[Lin]

A dehumidifier is similar to an AC unit.  The difference being that the AC condenser dumps the heat energy outside while the dehumidifier condenser just returns it to the internal space.  The condensate from the dehumidifier usually drips off the evaporator coils into a holding tank to be dumped in bulk, while the condensate from the AC unit usually is plumbed to drip outside the treated space.  However, the condensate from the dehumidifier could be plumbed to go outside, and the condensate from the AC could be collected in a holding tank.  The rooftop AC has the condensate plumbed outside.  That is why you will sometimes see it running down the side of an RV.

[Scott & Heather]

I guess to clarify, what I am wondering, does the moisture collect on the interior coils and drip into a pan that has a tube that leads OUTSIDE the INTERIOR housing of the A/C/ unit? I thought it was all sealed against the outside world...and that the A/C unit sucked interior air and blew it through cold coils....if the water condenses on them...again, does it drip onto a tray that eventually leads outside??

[Scott & Heather]

Lin,

I replied too fast...didn't read your post. Ok, that makes sense...so there is a plumbing system of sorts to collect the interior condensate and drain it outside...I always saw the drippage off the side of our coach, but always thought it was the external coils condensing and dripping. Now I know... Mucho thanks guys!

[Nick Badame Refrig/ACC]

Lol... But don't ask where the compressor is!

[lvmci]

Hi Scott,  look under your car passenger side behind the front wheel, in summer on a higher humidity day, when parked, you'll see a puddle, there's a hose from the moisture collection tray in the passenger compartment, thru firewall that drips down what was humidity inside the car, especially recirculated air as it blows over the coils, repeatedly, lvmci...

[Scott & Heather]

nice diag nick lol! again, you show the drip pan...but it's floating there...I assume there's a tube that leads outside...yep, in Florida on a summer day, the parking lots are practically wet with a/c condensation...Thanks for the clarification. I understand how A/C works, but when I had my housing completely apart, I never saw the physical mechanism to collect and transfer the water out of the interior housing to the roof of the coach. Nick, did you make that just for me?! I'm touched...

[TomC]

The evaporator (cold side) is sealed from the outside. Under the coils of the evaporator is a drain pan to catch the condensed water dripping off the coils. This has a drain on both the left side and right side (to accommodate whether the bus is tipped left or right) just dripping down onto the roof.  The pressure from the fan running inside the evaporator box keeps the outside dust and heat from coming inside. The amount of cooling air lost to the drain tubes is minimal.

[Scott & Heather]

Thanks Tom. Exactly what I was wondering. Now those who were too afraid to ask can merely
Read this thread without risk of looking silly....I'll take the risk, everyone on this board knows I'm silly....after all, I converted a bus....and I'm living in it. That pretty much certifies me.


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