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Old 07-10-2019, 06:37 AM   #21
wiredgeorge
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Originally Posted by bobnelms View Post
Sulphur1,

What did you do with the two holes in the ceiling left by the removal of the 2 roof-top ACs? That is, how did you plug those holes?
Holes are 14x14" and the same size a vents. That would be my first guess. Wish this guy were Stateside or someone here in the States did this mod as I would love to have a dual zone mini split in my 5ver. I don't have the skills to do it as neatly as this guy! Why some A/C guy doesn't pick this up is a mystery as my trailer was wired 30A and not braced for an A/C in the bedroom but in the Texas heat could really use one plus the mini-splits are more efficient than our roof top units.
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Old 07-10-2019, 11:08 AM   #22
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wiredgeorge,

From the photos that he supplied, he didn't use roof-top evaporators, but rather the standard wall-mounted evaporators.

But I'm with you. Not sure why US folks have not jumped on this, but I am suspicious that there might be a good reason.

I did cost-out a single zone, 110V unit installation that our local HVAC people would install and got a quote of $3250.00!!! And that's for a single zone. I could get it down a bit if I did it myself, but I'm not sure I'm up for that -- and it'd still cost in the mid $2K's.
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Old 07-10-2019, 11:34 AM   #23
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There are a couple of "issues to overcome" with installation of mini-split systems in RV's. First is the issue of voltage requirements. Most systems are 208-230 VAC. Using that in an RV would be difficult, even with a 50 amp shore power system. Not impossible, but you can't run a 220 VAC air conditioner on a 120 VAC 30 amp shore power campground plug.

Second, cost. A previous posted alluded to $3000+ for pricing.

Home Depot, with a "quick search" reveals a 120 VAC, 12,000 BTU system for $950. So, they are available, not quite as inexpensive as a rooftop unit ((13,500 BTU for around $525) but available: https://www.homedepot.com/p/ClimateR...SACH/304624913
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Old 07-10-2019, 02:10 PM   #24
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I sell Mitsubishi Mini-Splits and admit that the idea is very tempting. I have a display unit that I take to trade shows that I run off a 110v/220v power converter. The unit Sulphur1 mentioned is rated for a 15A circuit, so it doesn't seem impossible. A single Dometic 15Kbtuh unit requires a 20A 110V circuit.
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Old 07-10-2019, 02:39 PM   #25
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Mentioned elsewhere in this thread, thoughts are refrigerant leaks and dealing with condensate. All wiring and refrigerant connections would need to be vibration proof. I have not worked on standard RV roof ACs much but the lines are short and joints minimized. With a mini split you need to run the lineset in a way that does not trap oil, wont vibrate enough to crack or rub a hole in the line, and water proof power and refrigerant line penetrations. Not impossible, but it would take a very good installer and some extra work to bulletproof the install.
BTW, There are plenty of 120v mini splits.
Ideal installation to me would be a trailer with a rear entertainment area. The condenser could be installed out back, a short lineset run to the indoor unit mounted only a few feet away from the outdoor unit. Make it a heat pump for even better efficiency.
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Old 07-10-2019, 03:00 PM   #26
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My biggest concern with a mini-split installation is you can forget any type of manufacturers warranty. If it's not installed as per manufacturers recommendations, warranty is null and void. Pretty sure a mobile installation would guarantee that.
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Old 08-20-2019, 03:51 AM   #27
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I am eventually going to pursue this, but after a lot of thinking I believe I'll install 2, 110V systems instead of 1, 220V system. If I install 1, 220V system then I won't be able to use the system if I'm ever limited to a 30 AMP connection. If I install 2, 110V systems then I'll at least be able to use 1 of the systems.

I do wish you'd let us know how you plugged the hole left by the original dometic units.
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Old 08-20-2019, 04:51 AM   #28
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Originally Posted by bobnelms View Post
I am eventually going to pursue this, but after a lot of thinking I believe I'll install 2, 110V systems instead of 1, 220V system. If I install 1, 220V system then I won't be able to use the system if I'm ever limited to a 30 AMP connection. If I install 2, 110V systems then I'll at least be able to use 1 of the systems.

I do wish you'd let us know how you plugged the hole left by the original dometic units.
The "hole in the roof" is a standard 14"x14" vent hole. This is the "industry standard size" and all RV air conditioners that I've seen are manufactured to fit this size hole. Co-incidentally, RV rooftop vents are also 14"x14" and are manufactured to fit the same size hole as rooftop air conditioners.

So, if you elect to make the "split A/C mod" once you remove your rooftop A/C units, you'll need to install a vent similar to the one at this link "in the hole".

https://www.amazon.com/Motorhome-Com...gateway&sr=8-9

I would suggest, if you're not familiar with RV construction and if you're asking questions such as this, (an indication that you aren't familiar with RV A/C installation) then you really need to either "brush up on how RV's are built or consider hiring someone to do the work. Don't consider this a "put down" to your experience or knowledge, I'd tell the same thing to someone who wasn't familiar with heart surgery and was asking where's the best place to buy "sternum saws".....
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Old 08-20-2019, 05:04 AM   #29
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Thank you very much for your input. And no offence taken at all. I'm NOT familiar with RV construction and the best way to learn is to ask a lot of questions, right?

Anyway, thanks again.
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Old 08-20-2019, 05:31 AM   #30
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Thank you very much for your input. And no offence taken at all. I'm NOT familiar with RV construction and the best way to learn is to ask a lot of questions, right?

Anyway, thanks again.
Ask questions and get answers. That's one of the ways we all learn. My point was more this: If you aren't familiar with RV construction, attempting to modify and integrate RV and home style components so they work together is going to have some "hidden considerations" that may prove to be far beyond your experience level. In other words, if you're asking questions such as "what do you use to fill the hole left by the rooftop A/C?" you certainly won't have the expertise or experience to know what to do when you run across a laminated foam filled wall and need to run a wire through it, or how to seal the roof vent to the TPO (versus EPDM) roof membrane and whether "regular screws" or nails would be better to attach it to the 1/4" OSB roof decking.

I've been around and working on RV's for near 50 years and I'm not sure that I want to tackle the issue of installing a "home style mini-split A/C" in a travel trailer..... There's a heck of a lot more to that kind of installation than "what do you use to fill the hole in the roof?" It's a complex mod, one that includes venting, electrical installation, draining condensation, running thermostats, positioning for weight and balance with protection from road vibration, dealing with charging the Freon system, maintaining cool air balance inside the RV and probably a bunch of "pitfalls" that I haven't even thought about yet.

It's not just a "slap it on and it'll work" kind of mod.... Many would just say, "It's not a mod for the feint of heart".... I'd totally agree !!!!!
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Old 08-20-2019, 05:50 AM   #31
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This is getting interesting.

First of all, I would never attempt such an installation on my own. But the more I know, the better will be my decision on whether or not to go for it, and also who to employ to actually do the work.

But here's the thing -- as I said in my original post, I cannot STAND the noise of the current dometics. They ruin everything. If I invest on a replacement dometic and the same thing happens, where am I then?

SoI either have to sell my RV and get one with quieter ACs, or don't use the RV in the summer, or look for alternate ACs. I see no other options.

Secondly, there have been others who have done this. We've read about them on this forum. From what I've read, the largest issue is that of vibration. I'll not pursue this option until that issue has been addressed.

But I certainly appreciate your words of caution.
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Old 08-20-2019, 06:38 AM   #32
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If the noise (not cooling performance) is your "beef", then check into something like this: https://wackoproducts.com/
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Old 08-20-2019, 06:56 AM   #33
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Yes, the wackoproduct has been mentioned before -- although not too complimentary. But it's not just the noise of the air going into and out of the roof-top AC, it's also the noise and vibration of the compressor itself.

WaWaWaWaWa -- all day and all night long. There's some kind of resonance happening and it's bad. Everyone who gets inside hears what I mean.

I've had it to the dealer -- they don't know what to do other than try another unit.
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Old 08-20-2019, 07:59 AM   #34
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Yes, the wackoproduct has been mentioned before -- although not too complimentary. But it's not just the noise of the air going into and out of the roof-top AC, it's also the noise and vibration of the compressor itself.

WaWaWaWaWa -- all day and all night long. There's some kind of resonance happening and it's bad. Everyone who gets inside hears what I mean.

I've had it to the dealer -- they don't know what to do other than try another unit.
I know what you mean about the noise. I built a homemade box to dampen the sound, similar to what the wacko products box does. It does help.

I did have my original AC upper unit replaced when it lost it's charge. The newer one does seem to be quieter. The old one had a wump wump wump sound that was caused by the fan. I never was able to stop it but did reduce it a little bit by using some strategically located pieces of foam to isolate some of the vibration. You might also try checking the four bolts that hold the unit on the roof. Mine were pretty loose and tightening them up to the torque recommended by Dometic seemed to help a little bit.

Hopefully some day an enterprising entrepreneur will take the mini split idea and develop a functional AC unit for RVs that runs quieter, uses far less power, and is economically viable.
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Old 08-20-2019, 09:06 AM   #35
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Stevo, thanks for the reply. Yes, I have played around with those 4 hold-down bolts. I've loosened them, tightened them, etc. I've also made my own "damper" as it seems you have. It does help with the air, but not the wump wump. We can be in our bedroom at night, and not hear any air noise, but that wump wump wa wa drives us nuts.

Where did you place those pieces of foam?
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Old 08-20-2019, 09:18 AM   #36
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Stevo, thanks for the reply. Yes, I have played around with those 4 hold-down bolts. I've loosened them, tightened them, etc. I've also made my own "damper" as it seems you have. It does help with the air, but not the wump wump. We can be in our bedroom at night, and not hear any air noise, but that wump wump wa wa drives us nuts.

Where did you place those pieces of foam?
I just crawled up on the roof and pulled the cover off the AC. Then just pushed and pulled at different places with the AC running to see what happened and to see if I could identify anything specific. I think it was just that the fan assembly wasn't quite balanced. I'm sure if you spent enough time you could probably try to get it smoothed out by adding little weights to the fan blades but that's hit or miss and can end up with a bigger problem if you're not careful. You can buy the whole fan motor assembly and replace it for not much $$ but that would just be a shot in the dark too.
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Old 08-20-2019, 09:18 AM   #37
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You could look into one of these.

Dometic Brisk II Air Conditioner – Quietest RV Air Conditioner
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Old 08-20-2019, 09:25 AM   #38
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You could look into one of these.

Dometic Brisk II Air Conditioner – Quietest RV Air Conditioner
That's the one I have already. It's pretty quiet when it's not running! I have a ducted unit and I suspect each trailer would be different depending on the construction. Probably quieter in some and noisier in others. Here's the box I put on mine inside the trailer.
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Old 08-20-2019, 09:26 AM   #39
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That's the one I have already.
Sorry Steve the post was meant for bobnelms.
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Old 03-10-2021, 01:48 AM   #40
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from what i have seen. A mini split can control one or more out-puts. but all would be the same setting.. right?
my rv is small. but built as two rooms. air flow between them is not great.
would hate to need two units to do this job.
what about one out-put that blows air to the two rooms. instead of just one way. aka both sides of a common wall.
if this gets to costly it would be a no go for me.
this rv is not worth all that much.
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