Beat the heat - improve air flow from ceiling AC unit

[waiter21]

I’ve always had a concern about the roof top AC unit. It seemed like it doesn't put out the quantity of air that it should.

Last week I was removing the AC unit in preparation for re-coating the roof. I looked carefully at how the air flow is routed, and wasn’t happy with what I seen.


With the ceiling cover off I ran the AC unit. The large squirrel cage blower delivers a lot of air, straight down, toward the floor. However, when the ceiling cover is installed, the air enters into the ceiling unit, and is restricted by abruptly 90 degree turn and a 2 inch restriction. the air then takes several more 90 degree turns before it exits out the vents on each end.


What the cover really needs is a vent opening just below the blower that allows the air to shoot straight down toward the floor, unrestricted.

See entire article with photos below.

Beat the heat – Improving air flow from the air conditioner ceiling unit | 2001 Coachmen Mirada 300QB

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[Aggie_90]

My AC is already designed like this somewhat. It has a sliding louvres on the bottom so that I can open them to do a fast cooling of the main living area. Works great!

[Iwritecode]

Originally Posted by Aggie_90

My AC is already designed like this somewhat. It has a sliding louvres on the bottom so that I can open them to do a fast cooling of the main living area. Works great!

Same. Mine looks like this:



I've never seen a cover like the one shown in the article.

edit: No I take that back. I think my old pop-up had a cover similair to that.

[whj77372]

That looks like a stand alone unit, no duck work.
I have never had much luck with them. They can be loud
and they are on or off. Good Luck.

[northstar1960]

there are quite a few different styles of AC's used in RV's all a bit different so what is one way for one person may not be the same for others . mine is ducted in which works great or i can open the dump for quick cool which i don't use very much at all .
the way any of these units gets installed with duct work can adversely effect the way they work

[wrvond]

Good job! The name of the game is getting as much cold air into the living area as quickly as possible without feeding it back into the air intake.
Looks like you've succeeded.

[mguymon]

Mine is like this. It IS ducted

[Filterman]

Originally Posted by whj77372

That looks like a stand alone unit, no duck work.
I have never had much luck with them. They can be loud
and they are on or off. Good Luck.

The pic that writecode posted us like ours. If you want to cool the main living area fast, leave that sliding gate open and it happens fast. If you want to disperse through ductwork to others areas, close it partially or completely. Our's flows a massive amount of air when you have it on direct but it's finitely slowed down when you are cooling through the duct work.

[Wolverine 1945]

I am guessing waiter21 has an older model with out the option to open vent ???

[waiter21]

Correct, my unit is an older model, circa 2001.

My original ceiling unit didn't have the straight down vents.

It appears from the postings that some of the new units have this feature.

[Wolverine 1945]

If you could run it with the cover off,,, where would the air go ???

[waiter21]

If I run it with the cover off, the air blows straight down. When I cut holes in the cover to mount the louvers, one of the louvers is directly under the blower so air passes right through it and blows straight down when that louver is opened.

[GME2279]

Where is a good place to get filters. Mine is very then sponge like material. It can easily be out of place.

[Mikeschultz85]

Brilliant idea! I'm going to order the louvers and do the same mod.

My camper was made in 2013 and has the exact same ceiling cover. So it's not just the older units that are like this. :-)

Thanks!

Mike

[waiter21]

Mine uses a sponge foam filter. You can get them at any hardware store and cut it to size.

[Thurman]

Personally I think that was a darn good idea, cleverly and neatly constructed. On my unit, which is a ducted model, the cold air comes out next to the return air inlet. I got to thinking about this and wondered how much of the cold air goes right back into the return side with the dump open. First I did a smoke test done with a small smoke bomb bought at a local safety supply store. I was really surprised at how much cold air was going right back into the return grill. I took an ordinary manila file folder and taped it between the return and outlet grills. There was no doubt that the A/C performed better with more cold air being sent into the room. With the A/C grill set in the ducted position this is not a problem. Another smoke test proved that the cold air was coming from the registers in the camper and going back into the return air grill. I'm thinking of making something I can attach to the inside cover of the A/C when we first set up to help cool the TT down faster.

[SpringerPop]

My A/C/ cover looks identical to the OP's, and I WILL be doing this mod!

Pop

[Mikeschultz85]

Thank you so much for this. Just got mine installed, tested it out, and the DW told me to give you a big smooch! :-) What a difference that makes!

Mike

[Blktegra]

Great idea to help your unit out. The thought never even crossed my mind. I'm so anal about checking everything with a moisture meter after every time it rains and keeping the darn thing clean sometimes I overlook the smallest things. After reading this I discovered I have the sliding vent like the pic in the 3rd post. And although while open it cuts most of the airflow off to the rest of the hauler, it gives quite a nice cool down to the main area. Once the temp felt down I just closed her back up and sent the air on its normal path. Thanks for sharing your idea!

[SpringerPop]

Finished mine today. Didn't take any photos, but it looks identical to these.

GREAT mod, and I highly recommend it for non-ducted rooftop RV A/C units.

Made a BIG difference in airflow!

Pop