Hidden AC unit... Will this work?

[ddupre]

As you can see, I am not installing a galley. The middle cabinet will have a small AC unit. I know if I install a roof I will need to move air to keep it from cycling/freezing up. I decided to install a small squirrel cage fan venting outside, under the trailer. A small door will be installed in the roof and opened when the AC is on. Will this work?

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[bdosborn]

Why not put the A/C on slides and stick the hot side outside? Then pull it in and shut the door when you're traveling?





Seems like somebody around here has done that before

Bruce

[citylights]

Need ventilation to the hot side... And the built in fan needs to move fresh air through the coil. A lot of box installations fail because the forced air ventilation causes a air path short circuit.

Anyway, I like the idea of slides too!

[Tucguy]

If I may suggest that you study the placement of the optional air conditioning in the Camp-Inn teardrops. It does not detract from the aesthetics of the build and it is quite functional. Just my opinion. Form and function.

[eamarquardt]

Seems like somebody around here has done that before

Bruce

Care to mention any names? Cheers, -Gus-

[bdosborn]

Why, citylights has.

Bruce

[ddupre]

Thank you for your replies. So is the consensus is... it will not work? I still want to "hide" the AC. The fan will move a lot of air letting the heat escape from the bottom while fresh air comes in through the hatch. I am confused why this wouldn't work.

I appreciate the alternatives, i am kinda committed to doing it this way.

Many Thanks You's

[MtnDon]

A clearly defined path for the fan to move the air from one place to the other is required. All too often a fan is placed to blow air in one direction and proper ducting is not provided to make the air follow the path that is desired. Air will take the easiest route which may not be the path you imagine. Choice of fan is also important as many fans have poor static performance. That is they "suck" when it comes to pushing air through an obstruction like a finned assembly. It may be possible to make it work in an enclosed space IF you have proper ducting and a suitable fan. It does seem to me though that the units folks have mounted on sliders are easier to do and with more certainty that it will perform as desired. G/L.

[MtnDon]

The fan will move a lot of air letting the heat escape from the bottom while fresh air comes in through the hatch. I am confused why this wouldn't work.

Maybe I am not following your word picture very well. These window units all exhaust the warm air out the finned rear end of the condenser. Air enters that section of the A/C through vents on the top and one or both sides of the portion that is designed to hang outside. So the path you described would not work. Provision must also be made for the condensate to drain to the outside.

[GuitarPhotog]

In short, you can't cool the condenser coils with interior (air-conditioned) air. You must have outside air flow across the condenser coils or the whole works freezes up.

<Chas>

[citylights]

The fan will move a lot of air letting the heat escape from the bottom while fresh air comes in through the hatch. I am confused why this wouldn't work.

Maybe I am not following your word picture very well. These window units all exhaust the warm air out the finned rear end of the condenser. Air enters that section of the A/C through vents on the top and one or both sides of the portion that is designed to hang outside. So the path you described would not work. Provision must also be made for the condensate to drain to the outside.

That is a perfect picture and it illustrates how you have to duct it. Outside air must come in the sides without too much obstruction, so that the unit fan can blow it through the coil, and exhaust away- also without much obstruction.

These things are designed to be free entire and exhaust. Any obstruction (like putting them in a box) detracts from their designed air flow. Even if you add a, external fan, if you do not direct the air flow just right it may not work.

With that said, if you put them in a box, with few air restrictions for entrance and exhaust, and no air short circuits, they can work. An external air blower can also help. You just have to do it right.

Soooo much easier to put them on drawer slides!

[bdosborn]

A/C ducting isn't anything new around here. Crank up the search engine and you'll find lots of info

http://tnttt.com/viewtopic.php?f=2&t=4563

http://www.tnttt.com/viewtopic.php?t=56597&p=1025110

http://tnttt.com/viewtopic.php?f=21&t=37487



Bruce

[working on it]

The fan will move a lot of air letting the heat escape from the bottom while fresh air comes in through the hatch. I am confused why this wouldn't work.

Maybe I am not following your word picture very well. These window units all exhaust the warm air out the finned rear end of the condenser. Air enters that section of the A/C through vents on the top and one or both sides of the portion that is designed to hang outside. So the path you described would not work. Provision must also be made for the condensate to drain to the outside.

That is a perfect picture and it illustrates how you have to duct it. Outside air must come in the sides without too much obstruction, so that the unit fan can blow it through the coil, and exhaust away- also without much obstruction.

These things are designed to be free entire and exhaust. Any obstruction (like putting them in a box) detracts from their designed air flow. Even if you add a, external fan, if you do not direct the air flow just right it may not work.

With that said, if you put them in a box, with few air restrictions for entrance and exhaust, and no air short circuits, they can work. An external air blower can also help. You just have to do it right.

Soooo much easier to put them on drawer slides!

Agreed with all the above, but I wanted to try a "different" approach, an A/C that could run while sealed inside the hatch, and internally-mounted for ease of use for my own reasons, as related in this thread http://www.tnttt.com/viewtopic.php?f=21&t=54945&hilit=+duct And did I ever pay the price to be different; I rebuilt, re-configured it 3-4 times before it worked correctly. As stated by citylights, the unit has to have unrestricted airflow in three places (1.) the cool side (output) cannot intake too much already cooled air, it'll freeze up, (2.) the exhaust side must be allowed to vent freely, with little or no interference (this was my nemesis...too much heated air due to backpressure, causing thermal shutdown), and (3.) the A/C chassis needs to be able to cool itself, so unheated ambient air must be available. I had no problem with #1, #3 was OK (but I added a computer case fan to supplement the ambient airflow, just in case), but #2 required enlarging/straightening the exhaust ducting, and adding an inline duct blower to get all the heat out. I had committed to the idea of a ducted exhaust from the start, so I had to make it work. To do it all over again, though, I still wouldn't do the slide-out (again, reasons of my own, listed in my A/C thread), I would vent the exhaust straight out the back of my hatch, and not have any heated/right-angled exhaust duct backpressure to contend with. In the case of TinyTravelTrailers w/ A/C, just copy someone (else's) proven method, keep it simple!

[Vedette]

We are still reading.........hoping for the magical solution!
One that you can just order and install easily.
Please there must be something out there???
Good Roads
Brian & Sandi

[citylights]

Working-on-it... BINGO! You nailed the problems. Unfortunately, I see your understanding comes from personal experience. Still I would consider that a fun puzzle to solve. I am just strange that way...

Vedette... The easy solution is to use the pre-engineered and designed or manufactured solution. These things were made to hang their ass end out in the breeze! Aka window shaker. Install them that way and they work great. Put in a small modification to slide them in and out for storage and mission accomplished! Anything else is possible, just plain hard and more work.

Another possibility is to use the RV designed coolers. Most of those are roof mount, but some are duct mount. Too rich for my blood though $$$.