YES: RV Solar/ Li/ and AC running full time

[Lt.Dan]

Well, there's a 12v domestic 'split' now that replaces the roof AC...and it's quiet...

Dometic CoolAir 2000 RTX 12V | Nomadiccooling

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.. and this is the least amount of work ever....

I sent them an email asking them some questions. Such as actual wattage draw and if they offer a 48v model.

They advertise on their website 3a-60a for a 24v model, but I won't care for it if it constantly runs at 60a and only gets down to 3-10a for 5% of the time its running.

I also asked if theirs operates similar to a mini split with variable compressor speeds/fan speeds.

 

[Zwy]

Actual real usage and install on a 12V. https://diysolarforum.com/threads/solar-powered-12volt-air-conditioner-dometic-rtx-2000.21837/

If you have 48V, I'd opt to run 220V inverter and use a mini split.

 

[aangel]

@richard cabesa I'm inclined not to do it but still open if my power generation calculations show I'm not able to meet my project requirements without the extra juice. Still things to sort out.

@Zwy yep, saw that video and a few others. That's where I got my impression of the unit. For a specialized installation with narrow (read: not ambitious) cooling requirements and speed of installation (which costs money, too, especially if outfitting a fleet), it's worth the cash. I just don't see it being useful or cost effective in RVs and trailers. The capacity is too low and the price is still too high for what you get. Moreover, would 2000W/6,824 BTU be enough to handle the current heat wave even in just a van?

Sitting here I see that I overlooked one place I could put a cassette. I assumed it would be too small but perhaps not: right above the door.



The available width is 30" and the available height is 10" and that could be stretched to 13" by mounting the cassette away from the sloped wall. The Senville high-efficiency 9k BTU unit cassette dimensions are 28.43x7.36x11.42. The Senville ultra high-efficiency 9k BTU unit cassette dimensions are 31.57x7.44x11.69. If I go with the ultra high-efficiency unit, there's a bit of space on either side by cutting holes into the cabinets. Far less work and expense than going with a roof unit and it might be an easy way to support the unit, to boot.

The high-efficiency 9k BTU unit is $800 with 25ft of tubing and offers 19 SEER, -15C / 5F. I'm just interested in cooling, though, because I have a Webasto heater connected to my main gasoline fuel tank for the heating; paid $600 and it was shipped from Russia. The ultra-high efficiency 9k BTU unit is $1050 with 25ft of tubing and offers 25 SEER, -30C / -22F.

Goes to show you: don't make assumptions.

It looks like this will work without the trouble and expense of a ceiling mounted unit! I'm excited. Thanks again @Generis for spurring this investigation!

The next issue is moving the air from the door/eating area to the bedroom. That could be accomplished with the OPolar fans @Generis uses and mounting one just above the microwave:



I have a privacy curtain where he places his fans so that exact location isn't an option for me. Another possible location is below the cabinet to the left of the door and to the right of the light.

However, since there is already power to the ceiling, mounting a low-profile blower to the ceiling might work, too, if it's quiet.

This one runs on DC (I'd probably have to run a new DC cable):




This one has the the motor in the middle; he claims it's quiet but not very efficient with the single-pole motor and doesn't push much air. Still, a tangential fan might be perfect for my purpose. These are used in the cassettes, after all, and they seem to blow just fine and quietly, in my experience.


Diagram is from this informative article on tangential blowers.
Pretty ugly, though. Clearly needs some sort of cover since these are intended for industrial or concealed applications. After 30 minutes of searching it wasn't until I started looking for "air curtain fans" I started to see domestic products that might work.

Vornado Transom Window Fan with Remote Control (AC) ($99, June 2021) No new wiring needed.



Ha! For the ultimate in low-profile, there is this Sanus 12VDC rack-mounted fan ($109):


Following that thread, this one ($119) is just 0.5" taller than my current a/c unit, though it does have sharp corners that would be a problem for people 6'1" or taller, by my estimation:



Ok, I'm pretty sure I can find something that will move the air around.

I'm still going to run through the calculations but Generis has already proven that a SEER 19 heat pump and ~1kW of solar panels is workable under normal conditions. My guess is that even during a heat wave like we are currently experiencing the heat pump duty cycle would just be higher but completely capable of handling it.

 

[aangel]

YouTube just recommended a video of a highly compact 10k BTU unit that looked promising. However, the reviewer found it did not perform and it still uses a lot of electricity (1150W):
Forestair Mini Split 10K BTU Review For RV Application

Thus, there is no benefit to this unit when used in very hot climates and/or with solar.

"It's time for the RV industry to grow up and create a truly quiet a/c system for these travel trailers." (From the video above, Nov 2020).

I can't believe even recent trailers still use these loud a/c units. It's 2021, already. Is something better available as an upgradeable option?

 

[Partimewages]

YouTube just recommended a video of a highly compact 10k BTU unit that looked promising. However, the reviewer found it did not perform and it still uses a lot of electricity (1150W):
Forestair Mini Split 10K BTU Review For RV Application

Thus, there is no benefit to this unit when used in very hot climates and/or with solar.

"It's time for the RV industry to grow up and create a truly quiet a/c system for these travel trailers." (Nov 2020).

I can't believe even recent trailers still use these loud a/c units. It's 2021, already. Is something better available as an upgradeable option?

Not really. I have looked high and low but have not investigated the international market since sometime parts are a problem. There just isn't a large market for these types of units.

 

[aangel]

This reviewer provides a two-year update of using a residential unit, the Pioneer 12k BTU ($800), with his trailer and it's performing with zero problems. He does mention he would go with something a bit lighter. Shows how he mounted it, too, 2" away from the rear of the trailer.

Mini Split On RV Camper Trailer Conversion 2 Years Later Hows it Working???

Here is the other unit he mentions that was under $400 and made in Mexico:

CONFORTotal USA

CONFORTotal USA | Brownsville TX

CONFORTotal USA, Brownsville, Texas. 1,425 likes · 8 talking about this. MINI SPLITS

www.facebook.com

However, the SEER is low (11.4) and the power usage is high (970W/h) compared to the Senville and Pioneer units. Seems likely these units are out of contention for a solar build.

 

[aangel]

"There just isn't a large market for these types of units."

Are you sure? About 500,000 RVs and trailers are sold each year, this article says. Even a market of 25k units per year could be addressed by some manufacturer. There's definitely profit to be made here and this isn't rocket science. The more I think of this the more I think the RV industry has completely dropped the ball in this area.

 

[Partimewages]

RV industry doesn't make any of this. They assemble parts that are designed elsewhere. The buyers don't demand anything but less cost. Will that change? I think it has already to some degree. But that market is even smaller.
Several years ago a study showed that new home buyers used 3 times the amount of time to decide what color the kitchen cabinets would be as deciding what heating and cooling system to purchase. Your HVAC system is the second most costly monthly expense next to the mortgage!
Just shows most people's mentality. That's why I enjoy this forum. Outside the box thinking.

 

[aangel]

"RV industry doesn't make any of this. They assemble parts that are designed elsewhere."

I do understand that. However, I think an industry that ships as many units as the RV industry could work with a heat pump manufacturer to design something here.

"The buyers don't demand anything but less cost. "

I understand that, too. Still, I feel confident that if a potential purchaser were offered "the quiet a/c model" as an upgrade for just $500 more over 50% of the buyers would take it. I know I would.

It seems to me they are just being lazy and stuck in their ways. They need someone to come in and shake them up.

Maybe the Koreans will do that:
Motorhome from Hyundai that starts around $42K USD. Can you believe it? 1st RV car from Hyundai!

Hyundai says that with fully charged batteries the a/c unit in the rig above can operate for 6 hours. Lots more innovation, too, check out this more in-depth review.



I think they would sell a lot of these if they brought it to the US market.

Product page on Hyundai's site

 

[Partimewages]

"RV industry doesn't make any of this. They assemble parts that are designed elsewhere."

I do understand that. However, I think an industry that ships as many units as the RV industry could work with a heat pump manufacturer to design something here.

"The buyers don't demand anything but less cost. "

I understand that, too. Still, I feel confident that if a potential purchaser were offered "the quiet a/c model" as an upgrade for just $500 more over 50% of the buyers would take it. I know I would.

It seems to me they are just being lazy and stuck in their ways. They need someone to come in and shake them up.

Maybe the Koreans will do that:
Motorhome from Hyundai that starts around $42K USD. Can you believe it? 1st RV car from Hyundai!

Hyundai says that with fully charged batteries the a/c unit in the rig above can operate for 6 hours. Lots more innovation, too, check out this more in-depth review.

View attachment 53499View attachment 53501

I think they would sell a lot of these if they brought it to the US market.

Product page on Hyundai's site


View attachment 53498

That looks awesome! Although I need a little more room. I think you're right with someone else coming to market. Ofcorse 20 years ago I thought ground source heat pumps were going to do the same. But I still talk to people about them.

 

[aangel]

That looks awesome! Although I need a little more room. I think you're right with someone else coming to market. Ofcorse 20 years ago I thought ground source heat pumps were going to do the same. But I still talk to people about them.

"That looks awesome!"

Doesn't it?! I would want more room too plus some actual towing capacity for my motorcycle trailer. But they are showing what good designers and engineers can create when they start with a fresh slate. The bed that comes down from the ceiling is great and they obviously are using lithium batteries for the house storage.

At some point "soon" we should start to see all-electric RVs. After all, most people plug into power in an RV park anyway so it's the perfect application for 85% of the market. Or perhaps we'll see the new Tesla Cybertrucks towing some trailers in the next year or so. Should be no problem with a 400 mile range (not towing) at $50k. The 300-mile Ford 150 Lightning might also appear but at $80k I don't expect it to be common at first. Ford will have to up their game (better range, lower cost) before we see a lot of those.

 

[richard cabesa]

"There just isn't a large market for these types of units."

Are you sure? About 500,000 RVs and trailers are sold each year, this article says. Even a market of 25k units per year could be addressed by some manufacturer. There's definitely profit to be made here and this isn't rocket science. The more I think of this the more I think the RV industry has completely dropped the ball in this area.

Worse yet, a unit that would work well for many is actually made by Dometic. The Harrier rooftop unit fits in our roof hole,is about 10k BTU, dual cylinder inverter compressor, runs at about 500 watts and Dometic already has a supply chain in the US.

To bad they won't build it to run on US electrical sources

 

[Zwy]

@richard cabesa I'm inclined not to do it but still open if my power generation calculations show I'm not able to meet my project requirements without the extra juice. Still things to sort out.

@Zwy yep, saw that video and a few others. That's where I got my impression of the unit. For a specialized installation with narrow (read: not ambitious) cooling requirements and speed of installation (which costs money, too, especially if outfitting a fleet), it's worth the cash. I just don't see it being useful or cost effective in RVs and trailers. The capacity is too low and the price is still too high for what you get. Moreover, would 2000W/6,824 BTU be enough to handle the current heat wave even in just a van?

Sitting here I see that I overlooked one place I could put a cassette. I assumed it would be too small but perhaps not: right above the door.

View attachment 53493

The available width is 30" and the available height is 10" and that could be stretched to 13" by mounting the cassette away from the sloped wall. The Senville high-efficiency 9k BTU unit cassette dimensions are 28.43x7.36x11.42. The Senville ultra high-efficiency 9k BTU unit cassette dimensions are 31.57x7.44x11.69. If I go with the ultra high-efficiency unit, there's a bit of space on either side by cutting holes into the cabinets. Far less work and expense than going with a roof unit and it might be an easy way to support the unit, to boot.

I'd make up a mock up using a cardboard box and hang it there. Most cassettes require a minimim space above the unit to draw in air. You will find that dimension in the installation manual.

My guess is you will find out your head will bang the box entering or exiting.

 

[Zwy]

Not really. I have looked high and low but have not investigated the international market since sometime parts are a problem. There just isn't a large market for these types of units.

There is actually quite the demand for units that either can run off 110v AC, 12V/24V DC or a solar system. I googled "Truck Camper mini split" this morning, people have been working for solutions for 10 years now.

Either someone steps up in the US market or the Chinese will "own" that segment. Huge potential on just 12V DC and 24V DC mini splits in the truck industry with anti idling laws becoming more common and the cost to fleets that own a large number of trucks for fuel when trucks idle overnight to run the ac for the sleeper. Just fuel alone can make this economical in 1 year. Right now though for larger RV's and campers, the 110V/240V AC mini split is the answer until someone comes up with the better mousetrap.

There is a need and there is demand, it's just RV manufacturers don't want to change. I asked the president of one truck camper manufacturer why they don't offer a composting toilet option, his response was no one wants those. I told him he obviously never used a good one or he would make it available immediately. I'd take a black tank any day over the Thetford cassette they offer but I'll just install a C Head myself knowing I don't have to deal with outdated ideas. Just closed minds, "this is the way we always did it" and "it costs money for a redesign".

With the current push to more residential solar, we might see a huge demand for such products that don't need an inverter and can run directly off 12V/24V/48V DC.

 

[Generis]

View attachment 53427


I can fit 3 of the larger Trina panels and 4 of the slightly smaller ones with the A/C removed. From what I've been reading on this site, I likely want to go with the smaller panels since I can hook 2 sets of them up in series and then the sets in parallel, allowing me to use thinner cables while still isolating sets in case of shade. Plus, those Victron videos recommended preferring smaller panels to get more usable hours of sun in the day.

With the 4 panel setup, it looks to me that I could still tilt the two rear panels if I wanted to and the driver-side front panel (yes, front is at the bottom; it came from how I was sitting on the A/C unit when taking the measurements).

Next up are some power requirement calculations; sometime this week, I expect.

So,
Stacey and Thomas have a nice setup, and as you know from their install, the inside unit blows forward down the hall.. super ideal for distribution, but don't be afraid of using a 6 or 10 inch OPOLAR rechargeable fan instead (as I used) which move the air around just totally fine actually... and you can charge them only during sun hours if you want, the batteries last FOREVER seems like.

I'd go for the middle SEER Rating and save the top end $$ for more solar, because you need that more than you need higher seer. Anything over a 9k unit will do for your high temps, assuming you can block out the sun from the windows etc properly. I'll always recommend heavy dark blankets velcro'd to the walls..... because the actual window frame metal transfers a TON of heat from the sun directly inside.. and if you're going to be in hot desert conditions, use this method on the sunny side windows to totally block the heat transfer. The little plastic tin foil bubble reflector things work great, but not wide enough to cover the window frames usually... unless you have that solved by making them up yourself...

As shown in my post quote, I'm a fan of your 4 panel setup. 2s2p and lower gauge wiring coming down. Don't worry too much about shading. Everyone has something going in their head about this.. Example.. I was in a partly shaded 70 foot high tree'd campsite all weekend....... open over head, but the sun was always poking through the tree crowns at all times of the day, and I still managed to find over 400w of solar coming down.. out of a possible 820~ or so that I can usually get... so seriously... partly shaded hasn't killed my system down much at all really. If you actually try to be in the sun when you actually need a full boost, then you'll be totally fine. .. and my opinion on tilt.. not worth the hardware headaches for any travelling vehicle.. Do the set and forget method, and park in the sun. I'm at least 150 miles north of the top USA border, and I just don't bother with tilt. Even up here... Personal opinion.

... and remember.... keeping the AC running forever takes way less power than letting it get hot, then cooling everything, then you let it get hot again, and then cooling... etc... just leave it on forever, and enjoy. Way Way less loading.

ON the power usage for a 9K unit like mine.. I can easily get mine to hit over 1100w usage! Sure! Put it on Turbo mode, and Auto fan, and turn down the temp! If you want to hang meat, I can easily use 1100+ watts of cooling. Bottom line, not necessary. At all. But sure, it can do it.

I'll make a suggestion to any install.... First be sure your electrical setup can handle the LOAD first. Then supply enough panels. Then work on efficiency... little fans to help airflow, window dressings or shading, and that sort of thing. But be very very sure you're already giving each change enough time to prove itself. Examples:
Night time for us: we use the back bed, my 14 year old giant man-boy is in the cab bunk. We each have an OPOLAR fan to circlulate in the separate sleeping areas, and that's more than enough to keep everyone comfortable. It is, of course, still in the same air space as the main head unit producing the cool... so not much will change in the total air temp, and you're already going to bed on a cool mattress, etc. Once we figured out where to put the little 6 inch fan on low for the night, it's a dream. Give each change some time to prove itself.
Shading: you want direct sun to provide power. You shade where you DON'T want the sun producing interior heat. For instance.. parking next to slightly taller-than-RV trees on the SOUTH side will be great... shade for the RV, but the high mid day sun from the 'south' will still get the panels just fine. Not hard to plan that if there's any shade available at a boondock site (for example). Park with the door North. Or the most windows North. Some sort of plan like that for slowing the sun-on-window exposure will go a long way.

Regarding the 12V or 24V dometic roof units.. I suggested those simply because they are easy, not that they will do anything for your setup. I'll suggest also that easy is likely not best.

The headunit: I wanted to put mine over the door as well.. but my steps are 100% outside, and I have a double insulated floor on mine, so the door is high and at floor level from the first inch. Not enough room above the head unit. So I shifted it just FWD of the door and removed that front little cupboard. I don't miss it at all, and the cooling is in the living area, right where it matters. Perfect. As well, to note, there's nothing at all wrong with the size or function of our head unit.. it's not particularly low profile or any of that, but it's included in the cost of the mini, and it works perfectly. It also draws all the hot intake air directly off the ceiling, which is no bad thing either.. (be sure to leave adequate space above the unit for this)

 

[Bob B]

One thought I had about the 208/230 V units ...... If using one of these, it might be better to use a transformer instead of a 230 V inverter.
What I am thinking is that if plugged into shore power it would be better to have short power to transformer instead of having to use the inverter that would still be using battery power to power the cooling unit.

 

[Lt.Dan]

Whats wrong with just applying a normal 240 split phase without the neutral? Is an extra 10v going to fry it?

 

[Generis]

One thought I had about the 208/230 V units ...... If using one of these, it might be better to use a transformer instead of a 230 V inverter.
What I am thinking is that if plugged into shore power it would be better to have short power to transformer instead of having to use the inverter that would still be using battery power to power the cooling unit.

The safety idea here is appealing to me. That's a giant factor in any electrical installation. The input voltage doesn't change much on Invertor style mini split components. 208 or 110v, the unit is still going to invert to a higher voltage anyway. I'd suggest sourcing a 110v unit in any case to simplify everything, and keep the shore power safety simple as well.
No reason you couldn't find a good 12k unit on 110v if you needed that much cooling.

 

[aangel]

I'd make up a mock up using a cardboard box and hang it there. Most cassettes require a minimim space above the unit to draw in air. You will find that dimension in the installation manual.

My guess is you will find out your head will bang the box entering or exiting.

Good point. Hmm.

There is a piece of sloped wood that is right at the top. If I remove that the cassette can be positioned mostly flush to the ceiling. I just tested it and that will probably allow me (5'10") to enter and exit without ducking even if it needs a bit of space on top. It's still the best place for me to put the cassette, I think, even if I have to duck a bit (though I agree that would be annoying). But I will check the manual.

Ultimately I can remove the cupboard to the left; I just want to avoid that, if possible.

 

[curiouscarbon]

i’ve tested this for some DIY HVACk-ing. it uses little power and moves decent amount of air and fairly quiet for given airflow in my subjective assessment of about an hour of playing around with it. does not seem to produce very strong pressure so low fin count best to reduce pressure drop

Amazon.com: AIRBLAZE T14, Universal Fireplace Blower Fan Kit 14" with Temperature and Speed Controller, for Lennox, Hearth Glo, Majestic, Rotom : Home & Kitchen

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“ac infinity T14”

it’s marketed for fireplaces but it’s a very easy to integrate module imo. i have need for efficient DC air movers.