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Roof AC or Split AC?


Rescueduck

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Ok looking to see what everyone has on the Sunrader. What Roof mounted AC do you have and what do you recommend. Does anyone have a split AC system if so how is it working? Looking to purchase a AC for my Sunrader this  week or next just trying to make the best purchase. Thanks 

 

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Forget about a mini split to many unneeded problems. Don't go reinventing the wheel.

Get a 9,000-11,000 btu roof mount AC. Make sure your pricing the same complete kit not just the upper roof unit. Also depending on $$$ available the Dometic 11,000 BTU ac uses less power than the Colman Mach 8 9000BTU unit. This is important if you boondock and see a generator in you future.

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If I had the room for the the inside unit,  I would install a mini  in a heartbeat.   But I do have all the tools and knowledge for a proper install, which really is a big deal.

A 9k mini would be perfect size,  nice and quiet and would run on a 2000 watt genset with no issue.  The heat pump minis modulate and can supply from 2000 to 11,000 btu of cooling. 

Edited by jjrbus
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Hello All,

I've recently purchased a 1991 warrior with no AC or generator.  I've had the same question, so I ran a test today with a split AC.

The split AC I purchased is called a RolliCool split AC 10k BTU.  I got it because the outside unit fits in the generator compartment.

I got it, temporarily set it up with the lines running through a window blocked with cardboard.

I live in Denver and today was 80 with 40% humidity.  The test showed that today I could get the inside down to 81 when cloudy, and 88 when sunny.

So, I think either this AC didn't work or I need more BTU's  

This AC pulled 800 watts on my meter most of the time. And was actually pretty loud.

I'm open for suggestions and I'd love to post a photo, but it makes no sense to me right now.

Anyway, I hope this is helpful.

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I'm not sure there would be enough room or air flow in the generator compartment for the compressor to perform properly. It needs to be able to easily get rid of the heat and move fresh air across the condenser coil. I guess it depends on how you installed it in the box?

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I just placed it in the generator box close to the opening.  The opening was propped wide open to allow for airflow.  The fan on the outer unit blew hot air out.  It is completely temporary.  I can try again tomorrow with the outside unit sitting in the ground too.  That may answer that question.

20190706_195926.jpg

Cool, I figured out the photo thing!

Edited by pmstaats
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That's definitely a well fitting spot! Let us know what happens when you run it not in the box. I'm curious if the airflow is creating a circular vortex basically sucking the hot air straight back into the compartment and "recycling" it, which would obviously make the system not work. 

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Certainly!  I will try again with it out of the generator box tomorrow. I hope you're right!  This thing really does fit nicely.

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If that ends up being the issue perhaps you could create an "intake" vent from underneath the camper and then have a mesh exhaust vent in the door making it so you don't need to open the door when running the system. 

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Not an AC guy but have installed some mini's and yours installed in that compartment does not look like any of the install specs in the manuals.  They need to move large volumes of air and in an enclosed space are not going to do it!

Did a bit of experimenting with my 93 Sea Breeze and 8000 btu seems to be the best compromise.  Small enough that a 2000 watt gen set will run it dependably and just adequate cooling, sitting in full sun, no shade in upper 90's,  very high humidity weather in Florida.  The 8k is just keeping up temp wise, just under 80,  but in doing so is keeping humidity down which makes it seem much cooler.  

The portable minis were getting horrible reviews not that long ago,  now they have good reviews.  That is rather odd.    73% giving it a bad review! 

https://www.amazon.com/P800-F001B-Rollicool-Conditioner-Dehumidify/product-reviews/B0745L255K/ref=cm_cr_dp_d_show_all_btm?ie=UTF8&reviewerType=all_reviews

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Indeed, I took a chance but can return.  It's the only one of these that will fit.  Or, at least that I could find.  Interesting to hear that 8000 btus keeps you ~80 or so.  Is that 8k in the roof or do you have another method?

Edited by pmstaats
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7 minutes ago, pmstaats said:

Indeed, I took a chance but can return.  It's the only one of these that will fit.  Or, at least that I could find.  Interesting to hear that 8000 btus keeps you ~80 or so.  Is that 8k in the roof or do you have another method?

I looked all over America for an old 8k roof air. They are not made anymore.

Should have said I have an 8k window unit mounted in the bathroom window.   Not visually appealing but I would rather be  cool than look cool.  There is more outside with box for generator and metal frame to support AC. 

 

 

IMG_0001.JPG

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Oh, I see.  I've seen this option either where you have it or over the refrigerator in other installs.  The reason I wanted to try the mini split, in theory, is the efficiency bump (eer value) of this over a window, roof, or portable unit.  However, I'm not seeing this so far with this testing. 

I'm going to try a test today with the outside unit sitting outside instead of in the compartment.  I'd like to learn as much as possible with this option. I have hope...

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1 hour ago, pmstaats said:

Oh, I see.  I've seen this option either where you have it or over the refrigerator in other installs.  The reason I wanted to try the mini split, in theory, is the efficiency bump (eer value) of this over a window, roof, or portable unit.  However, I'm not seeing this so far with this testing. 

I'm going to try a test today with the outside unit sitting outside instead of in the compartment.  I'd like to learn as much as possible with this option. I have hope...

Should be a noticeable difference with it sitting out.     Measure the Delta T,     the temp of the air inside the RV vs the temp of the air coming out of the inside unit. 

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Well, that did not work as I hoped.  The outside unit was pulled about 2-3 ft away from the vehicle.  Temperature when I started the test was 99 inside and 75 outside.  After about 90 minutes, the temperature was 88 inside and 82 outside.  The unit was alternating between 45  and 60 degrees on the inside.  The unit on the outside was blowing air at about 104 degrees (F).  Please note the vehicle is in direct sunlight.  It seems the solar energy is overpowering this little split AC.  This unit says 10,000 BTU.  Are these the result that you'd get using a 10,000 BTU window or roof unit?

I think I'm going to pack this mini AC back up and send it back.  Not sure what the best move to cool it down is now.  Anybody insulate the inside with foam or anything like that to reduce the solar heating?  

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About your insulation ideas. Saw something that may be helpful. Remove everything from the roof. Use 2x4 or 2x2 to frame the openings. Get the roof sprayed with foam insulation, then use a truck bed liner to protect things. Leak proof, extra insulation and a white bed-liner will make the roof a lot cooler.

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45-60 inside should be giving good results inside?   My 11k roof air will cool the toy down in no time,  but is putting out 350 cubic foot a minute on high fan which is a lot of air.   The 8k takes some time to cool it down as it has smaller capacity  and puts out less air per minute.  I would expect a mini to take some time to get down to the temperature I wanted. 

I would check for large air leaks,  such as gasket missing on entrance door or some such thing.   Also opening a roof vent makes initial cooling go faster,  hot air rises and goes out while cool air fills in below.  

I know of no way to know difference in performance for one AC to another other than put it in window and see what happens.  Plus we do not know if the 10K is some arbitrary # or something made up.    For me personally in FL I think 10k would betoo big, it would be fine during the heat of the day,  but would not run enough to keep humidity down at night.   That is only my opinion and worth what you are paying for it :  )  

 

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It's a little hard to compare AC efficiency given the information in this thread.  Outside temps, starting inside temps, air sealing, direct sunlight vs. shade, humidity, cooling airflow, etc.    It's hard to say where the limiting factor is when trying to determine if the mini-split is working well or not.  But none of that matters to me because in the end I find myself agreeing with WME's suggestion:

On 7/3/2019 at 7:02 PM, WME said:

Forget about a mini split to many unneeded problems. Don't go reinventing the wheel.

Get a 9,000-11,000 btu roof mount AC. Make sure your pricing the same complete kit not just the upper roof unit. Also depending on $$$ available the Dometic 11,000 BTU ac uses less power than the Colman Mach 8 9000BTU unit. This is important if you boondock and see a generator in you future.

If you don't plan to use a genset then the standard roof unit is definitely the easy and simple answer.  On the other hand, if you have the technical chops and are willing to deal with installation issues and airflow and who knows what other issues, then the mini-split is certainly an option.  I find myself constantly wondering if i'd be better off with a mini-split, but so far I've not gone that route because I want reliability and I don't want to be chasing problems.  There are still more questions than answers out there with the mini-splits in RV's.

If you do plan on using a genset like the Honda eu2200i then I still think the standard roof top is still easier in the long term compared to the mini-split because it's more reliable and well tested, but you will have to add the right start up caps or a Micro Air EasyStart or whatnot to buffer the start up current.  

Overall I find myself cursing the RV HVAC industry on a regular basis for not making a more energy efficient and quiet HVAC unit for us.  The mini-split technology could be applied to RV's but apparently the return just isn't there to offset the R&D costs - maybe the market is too small.  So for now I deal with my very loud and power hungry roof top AC, but every time I turn it on I hope for the day that I'll be able to replace it with something that is reliable, quiet and efficient.  The current batch of mini-splits don't quite meet that application yet.  One day I expect they will ditch my old school rooftop unit, but I'm not willing to be a foot soldier in that battle right now.  I just got back from a weekend boon-docking on the Chattahoochee River banks and I was able to stay cool enough in 93+F temps in Georgia with humidity topping out at 95% with little shade to be had.  My honda eu2000i and 8 year old 13.5kbtu Carrier AC (with Micro Air EasyStart installed) never had an issue.  For now I'll stick with what's proven to work under stress.

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That sounds like proper, tested knowledge.  Thank you for the information.  I'm packing up this silly RolliCool unit and back to Amazon.  Bezos can figure out what it's for, definitely not this last application.  Tests show abject failure.  

I really do not like the rooftop units, so I'm going to try some other tests.

I went to Best Buy tonight and picked up an 8000 BTU window unit and will test it sticking out the window in the sun tomorrow.  I'll post this as a new topic as its neither rooftop or mini split anymore (topic of these message strings).

My efforts using a mini split panned out poorly.  I hope everyone can learn from this and try something else (different mini split or different method).

That RolliCool mini split is pretty bad all around.

I named it RolliCrap.

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If it works out OK, think about mounting the unit on a set of roller drawer slides. A flange on the outside and inside will seal things when driving and when you push it out parked.

A former member "Waiter" did a super install, here's his post...http://toyotamotorhome.org/forums/index.php?/topic/4077-how-to-window-ac-in-dolphin/

 

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Some duct tape, cardboard and a scrap lumber bracket to test.  Did not drive anyplace like this,  only to experiment with AC size.  I had read enough on the net to know the 5 or 6k window unit would not be large enough, so went directly to the 8k.

 

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Asian motorhomes/campers have been using mini splits for quite some time. They are considerably more efficient and a great deal quieter. You do not see window units in Asia. The US is just catching on to mini splits we are years behind Europe and Asia and they heat too ! Guess that's why the units come from Japan.  

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Black &Decker sell some 8K portable units for about $320 on Amazon. They sit on the floor. If you have the space that would be the way to go. 

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9 hours ago, pmstaats said:

I really do not like the rooftop units

I completely understand.  I think WME's link to Waiter's install is a good option for you.  I find that the window units are really cost effective and not horrible on an energy efficiency rating.  They are generally rugged enough to handle the task.  A main downside is the need to cut a hole in the camper wall and the aesthetics of having the back half of the window unit sitting all the way outside to allow for cooling.  The slide out window unit is a good idea if you have the space for it and are willing to cut a hole in the side.

7 minutes ago, Maineah said:

Asian motorhomes/campers have been using mini splits for quite some time. They are considerably more efficient and a great deal quieter

I can't wait until reliable, purpose built units for RV use start arriving on our shores.  It seems like there is so much to gain in terms of less power to start/run and lower noise.  It's too bad that it's so awkward to adapt the existing configuration for use in our rigs.  

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2 minutes ago, fred heath said:

portable units

Don't be tempted by portable units.  They have to have tubes connected to the outside to blow hot air out to cool the compressor.  The ones with one tube pull air from inside and push it outside, and the make-up air has to come in from outside. In the small area of a camper this is ineffective because it's so small, you end up pushing cooled air outside.  Other portables have "dual tube" setups with a pull and push tube to cool the compressor.  This is better, but still not a good idea because the units are designed to evaporate the water that condenses inside instead of draining it.  This takes a lot of extra energy.  Also, the portables are not small either.  The window units are much more compact.

I recently had a central HVAC system go down and I got two temporary units to use until it is replaced.  One was a 11k window unit and the other was a 14k dual tube portable.  The 11k unit has way more effective cooling power than the 14k unit.  this is primarily due to the heat (energy) used to evaporate the condensate in the portable.  I've been very disappointed with the portable unit, but I needed one of them to not hang out a window so that's what I had to work with.  The 11k unit was half the cost of the 14k unit too.  My high relative humidty in Atlanta certainly impacts the comparative efficiency.   

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38 minutes ago, AtlantaCamper said:

I completely understand.  I think WME's link to Waiter's install is a good option for you.  I find that the window units are really cost effective and not horrible on an energy efficiency rating.  They are generally rugged enough to handle the task.  A main downside is the need to cut a hole in the camper wall and the aesthetics of having the back half of the window unit sitting all the way outside to allow for cooling.  The slide out window unit is a good idea if you have the space for it and are willing to cut a hole in the side.

I can't wait until reliable, purpose built units for RV use start arriving on our shores.  It seems like there is so much to gain in terms of less power to start/run and lower noise.  It's too bad that it's so awkward to adapt the existing configuration for use in our rigs.  

I have seen some pretty neatly done RV setups using mini splits one had the power unit mounted on the tongue of a trailer another mounted in what I guess was a unused generator compartment.

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There seems to be more and better options around the world for RV cooling than in the US.  

A window ac for under $300 seems like it would be the best way to go.   I like the mini's and that is what I have in my house, but the inverter mini's are more computer than AC and if an issue comes up it will likely not be a simple or cheap fix! 

https://www.google.com/search?client=firefox-b-1-d&q=1.5+kw+to+but

About $1200 us for 5k btu!

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I still think that a "normal" RV roof AC is the answer. But crawling around the web I found some thing that might be sorta of an answer.

A ceiling cassette for a mini split...https://www.pioneerminisplit.com/collections/cyb

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Why are people steering away from the standard RV units in the first place? 

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I can only speak for myself,   they are too expensive for what you are getting.  I have never heard a RV roof unit with an acceptable noise level.   Except for the Polar Cub at 9000 btu which has many noise complaints the smallest roof air is 11,000 btu which I believe is too large for my Toyota.  I notice some of the Toys originally came with an 8000 btu roof air, which has been discontinued.  

I also want to run my RV with a 2000 watt Honda generator,  the Honda will run an 8000 btu AC dependably under all conditions or would run a 9k inverter mini split with no problem.   The 9k inverter mini modulates,  will run between 2000 and 11000 btu, depending on conditions.   

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1 hour ago, Odyssey 4x4 said:

Why are people steering away from the standard RV units in the first place? 

For me it's 1) noise, 2) high current draw on startup making generator use tedious, 3) overall low-ish energy efficiency, and 4) I want my roof back

I think all of those complaints could be addressed to some extent with the mini-split technology if properly packaged for RV use.  But until that day comes I'll stick with a standard roof unit.

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Thank you WME!  

I looked at that AC / Wall install above the fridge.  Very good detail and seems fairly straightforward.  I am going to try a "mocked" setup when it hits 90 here in Denver tomorrow.

 

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I have seen new Jayco camper trailers with a factory installed window type unit built into a wall it's kind of hooky looking with a guard over the outside part. The neatest was a total interior rebuild with a window AC unit built into a cabinet under the counter top.

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Results from mock up?

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