High Efficiency Air Conditioning Units for non-generator powered campers

Haf-E

Expedition Leader
Thanks - didn't think about the EER being dependent on metric / imperial ratings...

I wonder if the test conditions for EER are the same in Australia as in the USA? 95F dry bulb temp / 75 F wet bulb temp 50% humidity?
 

S2DM

Adventurer
Ive heard Earthroamer uses a window mount residential unit. Anyone know the model and efficiency?
 

LeishaShannon

Adventurer
I wonder if the test conditions for EER are the same in Australia as in the USA? 95F dry bulb temp / 75 F wet bulb temp 50% humidity?

We use ISO5151-T1 which looks similar --

Indoor:27 C/80 F DB - 19 C/67 F WB

Outdoor:35 C/95 F DB - 24 C/72 F WB
 

DiploStrat

Expedition Leader
Unless Things have Changed ...

And they may have, both Tiger and Earthroamer have used 6k BTU residential A/C units. Mine is a Sharp with an EER of about 10.7. Earthroamer has played with expanded metal grills to hide the unit and with ducting. Tiger leaves the A/C exposed for ease in cleaning the filter.

The advantage is that they are cheap (>$300). The disadvantage is that the mounting is hard, as you must provide drainage for the condensation and air intake for the condenser side of the unit, a challenge when the A/C is enclosed in the camper body.

Potential advantages of a 12v unit are:

-- Can use a smaller inverter, although, to be fair, the savings in weight, cost, size, and efficiency are not THAT great once you exceed 2000w.
-- Some 12v units use multiple, staged compressors, that is, both on at start up, but then only one runs to maintain temperature.

With an inverter and small residential A/C you are looking at between 50 and 60A when the compressor is running. On a sunny day, I get back between 20 and 30A from solar. At night, there is no solar input, but, on the other hand, the duty cycle may well drop below 50%. I just haven't had the time (or the temperature) to run any real tests.

N.B. Like a lot of folks, I am very protective of my batteries. Normally, I would have a fail-safe in the low voltage cut out of the inverter, but, as I use an induction stove top and a microwave, I have to set that voltage much lower than I would like as the voltage plummets and then recovers. (I could, of course, reset it higher for over night use.)

 
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david506th

Adventurer
Ive heard Earthroamer uses a window mount residential unit. Anyone know the model and efficiency?

For ease of use, repair & cleaning I plan to go with a small window unit. I studied the Tiger & Phoenix way of doing things at Expo and have researched the Earth-roamer. The drop in roof top is nice but I am already tall enough.
 

S2DM

Adventurer
For ease of use, repair & cleaning I plan to go with a small window unit. I studied the Tiger & Phoenix way of doing things at Expo and have researched the Earth-roamer. The drop in roof top is nice but I am already tall enough.

A basic window unit is substantially higher efficiency in the 5-10000 BTU range than an RV roof top unit, so It seems like a good call. Have you decided what unit yet?

I guess the standard RV unit is planned around being on shore power, but I am still trying to wrap my head around why there are such differences with EER ratings between the RV stuff and the truck stuff vs the residential units.

Has anyone heard of any issues with mini splits or window style units rattling apart with modest off road use? I have a great spot for a mini split in my build, but am concerned about longevity in Mexico. I've seen some recommend in other forums to replace the copper lines between the two portions of the mini split with automobile ac coolant hoses to limit that as a point of failure from copper fatigue and subsequent breakage.
 

LeishaShannon

Adventurer
Has anyone heard of any issues with mini splits or window style units rattling apart with modest off road use?

Not yet... :)

acinstall.jpg

Our truck is 4WD but the sheer size of it limits off road use to muddy roads and beach driving. If you can fit and power an AC unit you're probably not rock hopping... so I think the 100s of kms of corrugated outback roads are more likely to cause issues than the occasional big knocks off road.

Before we stuck the unit to the roof (literally, its glued up there) I pulled the cover off and cable tied anything that looked like it could move. The hoses between the outdoor and indoor unit are also restrained to minimise movement. The grey cover reduces dust and has a roll up zipped section to expose the fan exhaust.

Residential AC units are available and repairable in pretty much any small town but RV units not so much. We figured that given the price difference ($750aud vs $3000aud for a traditional roof top RV AC here in Australia) we'd just repair / replace the unit if it fails. Its not exactly a critical system... (although Leisha might disagree on a cold night..)

I am still trying to wrap my head around why there are such differences with EER ratings between the RV stuff and the truck stuff vs the residential units.

I think it might be to do with size and layout, the RV units are more compact so its harder to seperate the components. Residential AC is also a much bigger market than RV so there is more money spent on R&D too...

I guess most RV units live on large motorhomes that plug in the second they arrive at an RV park and when you're chewing someone elses power you probably don't care about efficiency too much :)

For off the grid use I can't see how a unit that uses twice as much power can work unless you have ****loads of solar. We have 1200W on the roof and 400W portable so the ~200W (~18A @ 12v) average consumption is OK after other loads are taken into consideration. That said we still couldn't run it in heating mode all day and night.

An AC is a lot of additional weight to be carrying if you're only going to be able to run it for an hour before the batteries go flat.
 

S2DM

Adventurer
Here is another interesting unit..

http://www.hotspotenergy.com/solar-air-conditioner/HotSpot-ACDC12b.pdf

Its takes both direct DC input from your panels, and supplements with AC as needed. Requires 30v or greater panels. They claim an SEER of greater than 35, but it looks like that is just calculating the ac requirement when the mini split is receiving a full DC output from the panels. Perhaps not the best math to use in an offgrid camper where solar output is what you have, and any AC power is just generally inverted DC power from the batteries, which ultimately came from the sun.

Its efficiency as a AC powered unit is just ok as ductless mini splits go. I'm wondering if this might be better in an AGM battery powered camper, where getting those last bits of charge in get increasingly hard and more power is wasted from the panels? Once the batteries are topped, all of the solar output could be put towards the Air con.

Could also potentially be powered direct DC with a step up transformer bringing your 12V output to 36 volts.
 

S2DM

Adventurer
This looks interesting as well: http://www.cruisencomfortusa.com

It does. I can't find any reviews from truckers who use them, but plenty in the marine world. They do custom AC units as well. I'd thought about a hybrid split that is both water and air cooled, with the water cooled loop being used to heat your hot water tank and then exiting to the heat pump for the air cooled portion once the water is hot. EER is around 12, so better than the domestic 110 units, and no inverter losses on top of that, so the gap widens and brings it closer to the mini splits, which require 230v.
 

campo

Adventurer
Considerations and practical experience with some of these units

Hi all
.
I am discovering this interesting thread. In my personal MAN TGM 4x4 I did some testing and installations in order to get more practical knowledge and not only about sales specifications. Maybe I can present the systems for you. I have no generator on board (just a small Honda 20i for emergencies) and only 530Wp solar.
I have experience with bigger vehicle air-conditioning all over but testing and comparing in different conditions was learn full for me.
.
First I would like to give you my personal opinion about using home or office air-conditioning (230V or 110V) equipment on vehicles. Although many have already been installed It’s not made for this purpose. Here in Europe there are lots of safety regulations and there is no approval for using it in a camping truck or vehicle. The grey zone is that you would only use it stationary and not mobile whilst driving but consider that it could also be used whilst driving. Second point is that these household units do not always resist to heavy shocks and off-road conditions. Look at the tiny plastic parts and ultrathin copper tubes and alloy fans. The third problem is carwash, water spray and salt conditions on the road with inside the units electrical deadly power components.
.
It’s a pity that you cannot use them for your camping vehicle because the price is lower, the EER/COP is much better and the most important is that they have the lowest noise level.
.
This does not mean that units specially made for big trucks or RV’s are that good and have perfect specifications but the advantage is that they are made for the purpose from the start. I know most of the air-conditioning units as Dometic, Truma, Coleman, Air command, Indel-B, Autoclima, Webasto, Eberspächer, and some others. So I could choose.
.
I tried to find units with possible low power consumption on the batteries (4x12V/220Ah in a 24V system)
First I calculated the needs considering that I had 2 stationary conditions:
- The normal one is the environmental temperature you get 70 or 80% of the time where you need AC. (outside temperature between
- The extreme one is the one you will rarely have to deal with but as it is an expedition vehicle you go through this one.
Then there is the economy consideration that you can reduce space whilst sleeping. You can only cool the sleeping compartment and not the complete vehicle. If you do so you can win hours on the batteries mode usage.
.
My idea was environmental temperatures up to +45°C and normal temperatures around 28°C
Extreme conditions are for me cool down from outside shadow temperature +45°C to +28°C
And normal conditions are cool down from +28°C to+24°C
I had to take care about the insulation, windows, roofs, ventilation loses, electrical fridge heat and warmth of 2 persons on board.
These are the specifications of the air conditioning systems on board
.
Driver cabin air conditioning:
- Dashboard OEM unit with automatic regulation ca 5.000 Watt
Engine driven AC compressor with clutch
.
Living cabin driving air conditioning:
- Extension on the dashboard AC unit 4.000 Watt
- With electromagnetic valve and thermostatic regulation
- Dashboard on/off switch max 450 m³/h
.
Living cabin stationary air conditioning on 24V batteries:
- Split air conditioning unit regulated from max 1.800 down to minimum 600 Watt
- Integrated evaporator 350m²/h 3 speed max 35A /24V
- Double 24V hermetic compressor unit BD350 min 13A /24V
- Condenser outside on the front wall max 450 m³/h
- Economy use possible (on only one compressor)
- Digital controller
.
Living cabin under bench air conditioning on 230V:
- Stationary under bench monoblock unit 1.800 Watt
- Dometic Freshwell 2000 on inverter 28A/24V
- Ducted to the roof ca 2,8A /230V
- Remote control with sleep timer max 350 m³/h
- Can be used through the on board 24>230V inverter
.
Do not hesitate if there are questions
Campo


View attachment 313895
 
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LeishaShannon

Adventurer
Here in Europe there are lots of safety regulations and there is no approval for using it in a camping truck or vehicle.

Wow, I thought Australia was bad. We're usually heavily regulated but theres no restriction on mounting a domestic AC on a vehicle here that I'm aware of.


Second point is that these household units do not always resist to heavy shocks and off-road conditions. Look at the tiny plastic parts and ultrathin copper tubes and alloy fans.

We're treating ours as disposable although we know of people who have got 10+ years out of them mounted to caravans.

Our unit was 1/3rd the price of a vehicle AC (or rooftop rattler as we call them down here) so we can swap it a few times and still be ahead on price.

But, as you touched on the main reason for using such a unit is efficiency. Last week we had 3 days in a row of 38c and I was able to run the AC 24/7 in silence from solar alone. This just wouldn't be possible without the 5.71 (19.5 imperial) COP of the mitsubishi unit.
 

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