Most Energy Efficient Air Conditioner?

[NickSEspi]

Hi all,

I'm just starting the build out of my 2005 170" Sprinter and I'm looking for suggestions on the most energy efficient Air Conditioners out there.

I know that AC is an energy hog, but I definitely want it. I work seasonal gigs on public lands so I travel a lot and should be ready for some extremes. I'll be living out of the van with my dog full time and want to make the space as comfortable for him as possible while I'm at work. I hope to live off grid as much as possible so I'll be going in heavy with the solar power and batteries, but I am prepared to park somewhere where I can hook up to shore power if necessary during the hottest days of the year.

I plan to pair it with a good quality ceiling vent fan and would love if the AC had a fan only mode, especially if it allowed me to change the direction of the air flow. I might also create heavy duty insulated curtains to wall off sections of the van so the AC only has to cool a small area.

I don't have the rest of the electronics picked out yet. but figure this will be my biggest drawing appliance so I'd use this as the foundation that I'll spec the rest of the rig around.

What are your thoughts and experiences with this?

Thanks for all the help!

 

[Shawn182]

So "energy efficient" and AC for a Van do not always go hand in hand...meaning the lowest power draw might not be the most efficient.

You will likely have less of an overall draw from a power hog that cools the van quicker and can drop to a lower power cycle to maintain vs a smaller unit that is always running at 100% to keep up.

I have a Dometic Penuin II and does the job great. Has fan mode but have not seen any yet that run in exhaust mode. I would couple AC with a Maxfann Deluxe which runs both directions.

Just for a real world data point...if you want to run a traditional rooftop AC off battery for any duration, not will need 100AH of LiFePO4 battery capacity per hour of runtime desired in the hottest temps.

If you will have access to shore power, I love the Victron Hybrid Inverter/Charger. If you only have access to say a 15A sketch wall outlet it allows you to dial in exactly how much to draw from shore power and will supplement the rest from the battery and eliminates the need for a transfer switch. Last last week I was somewhere where all I had was a light duty extension cord someone loaned me and was able to plug in and dial it back to 10A max draw which extend my battery life exponentially with AC running even though I did not have a 30A hookup available.

 

[DieselBurps]

Any of the newer rooftop units you might be able to get away with running on a 15 amp circuit provided you don't try to run any other high draw items at the same time the AC is running. Otherwise, to run off batteries you are looking at around $15,000 dollar investment, hopefully that's not an entire summers salary.

 

[Midwestdrifter]

The best units are compact mini splits. There are some with Coefficient of Performance above 3.4. They are not easy to mount to a van though.

 

[Kajtek1]

As far as I know nobody makes AC efficiency comparisons, so you can't really make your decision by that.
I did own several RVs in my life and am always annoyed when small RV has "Balloon" sized AC on the roof.
Evidently customers don't request low-profile units and the live not only with the "looks" but also with higher air drag.
So my recommendation get low-profile and whatever it will bring. Years ago I bought Carrier, who had "splash technology" who was splashing condensation water inside the unit. That preventer annoying water drips on the siding.
Now leaving pets inside RV with working appliances is high-risk procedure. I hope you will have WI-FI and remote thermometers, or video who will allow you monitor the pet?

 

[Midwestdrifter]

The energy efficiency ratio is available for home AC units of most sizes. RV units aren't usually treated like that. Your can Google the conversion ratios. The simplest comparison is power in to cooling power otherwise called COP.

 

[marklg]

As far as I know nobody makes AC efficiency comparisons, so you can't really make your decision by that.
I did own several RVs in my life and am always annoyed when small RV has "Balloon" sized AC on the roof.
Evidently customers don't request low-profile units and the live not only with the "looks" but also with higher air drag.
So my recommendation get low-profile and whatever it will bring. Years ago I bought Carrier, who had "splash technology" who was splashing condensation water inside the unit. That preventer annoying water drips on the siding.
Now leaving pets inside RV with working appliances is high-risk procedure. I hope you will have WI-FI and remote thermometers, or video who will allow you monitor the pet?

A typical RV AC in the middle of the back also takes up space where you could probably put a few hundred watts of solar panels. I would look for something that does not take up all the roof space. But, unless you have really deep pockets for a whole bunch of batteries and some way to charge them, you will need to run off shore power or a generator. We can run our AC and other small appliances off a 15A circuit no problem.

Regards,

Mark

 

[mikecol]

I have 144 WB Cargo and installed an Advanced RV Quiet AC (Houghton Belaire). This unit is huge area wise, but not super tall. Has AC, dehumidify, and fan mode (only one direction). AC typically runs about 7-9amps on 120AC. The dehumidify mode has a lower duty cycle and seems to work great. I also have a Maxxfan so can put both in fan mode for air loop.

As other said, you will need big battery bank if you want to run standalone. I have 1100AH LifePO4 (10X Trillium) bank so can run AC for awhile. With the limited area left on the 144WB van, it is not worth having solar for me...I use shore power or B2B to recharge. Xantrex 3KW inverter lets me dial in the shore power desired current limit (5amp steps), so usually limit to 15A to plug in anywhere (giving 85A 13V charge).

 

[HarryN]

In the past I have looked for a roof air conditioner that was both an exhaust fan and air conditioner. While I have not looked in the past 12 months, at that time I didn't find any for sale in the US.

There was a model sold in AUS but of course it was 50 hz and I wasn't interested in dealing with that at the time.

It is definitely true that out in the middle of BLM land, you will need air conditioning and it will dominate your energy needs.

A simplistic way to think about it is:
- A roof full of solar panels is about enough for your normal house needs such as refrigeration, etc
- Solar panels for air conditioning will need to be deployed out in the sun with the van in the shade if possible.

Assuming that you want a reasonably first world living experience, but want it to be as much "solar powered as possible", one possible configuration would be:
- ~ 8 battle born batteries (or equivalent) powering a 3 - 4 kW inverter
- 300 watts of panels on the roof
- ~ 3 kW of flex panels deployed out in the sun with the van in the shade

That would provide enough energy each day to power the air conditioning that is used plus recharge the pack.

Size wise, the ground area covered by the roll out or foldable panels will be ~ 10x larger than your van.

Budget wise, that is ~ $25-30K of hardware.

It isn't difficult to do this, its really just the financial commitment.

The non solar alternative is to buy something like a honda 7000 generator. ( ~ $5K) It has a fairly large fuel tank to make it through longer run times.

The typical honda 2000 and 3000 have too small of a fuel tank to run all day in your application. Consumption would be ~ 4-5 gallons per day - so $20 of fuel.

There are variations on this theme but not "factor of 10 better" options.

 

[Kajtek1]

I actually measured power draw on my AC in different RV and 15k BTU Carrier was taking 8.6amp on full blast.
Smaller AC (I think 12.5k) on my camper draws 6.3 amp.
When the power draw is low, bare in mind ACs without soft start need like 20 amp peak, so even 2000W generators won't handle them.
Either way, you won't be able to run AC on solar power for sure. In last years we mostly camp in hot areas, where AC has to run whole night. Having Honda EU3000 - it will run about 15 hr on its 2.7 gallons tank and AC on full blast.
Even with heavy use, calculating solar and batteries cost for day use, it will take about 99 years to recoup the cost.

 

[65C02]

Re-Soft start
I'm also in the process of settling on a electrical/cooling plan for my 170. The bigger/taller A/Cs seem to be more efficient - for me, I'm not necessarily looking for the most efficient - but lower draw and low profile. So, I'm looking to get a Coleman Mach Cub - 9200btu, 11.7amps. I figure if it cant bring the temp/humidity down we can always start the engine. With a planned 200ah lithium charged via the AUX alternator/ balmar regulator, I'm skipping solar entirely. If we need off grid AC, a small generator feeding a Victron Multipass inverter/charger will start AC using inverter's power assist mode. (also helps solve sketchy /current limited shore power) https://shop.pkys.com/powerassist-demo If 2nd A/C is needed while driving, the 2nd alternator can extend unit's run time while charging batteries. Charging/running current from alternator will be limited as not to fry the alternator or belt. Van has N62 option. We're looking to run A/C if we run into store, grab a bite to eat or are waiting for a ferry etc. so under 1hr on battery to keep us/dog cool - or to make humidity disappear while camped. Beyond that, run generator or plug into shore power. For the OP, it seems longer run times are needed, so either more batteries or a genset are needed. If you are away from van for hours, plugging in would seem the most reliable from your dog's perspective. Even then, I would have a notification system - its not like a house that takes hours to heat up.

 

[Tripol]

Powertech generators makes a 3kilowatt diesel generator that mounts where the spare tire is on a sprinter, I believe- they claim it uses one quart of fuel per hour on a full load. I think it’s around 5-6 grand, maybe another option for powering an ac

 

[NickSEspi]

Thanks for all the replies!

Just figured I'd note that I've lived in housing without air conditioning for a few seasons so I'm not looking to run the setup at 73F or anything, just looking to keep it bearable during peak hours. My van with the pup will most likely be parked somewhere near my job sites so I'll be close by just in case. I'd like to find a remote monitoring setup that could at least give me temp, battery capacity, and maybe even a webcam, but that's for another time.

I was already anticipating the need for around 1000AH of batteries. I figure if its really only necessary for the hottest hours of the day, and during heat waves where its like that all day I'll track down shore power. I imagine that would be easy enough to manage. I'm not interested in getting a generator and the fold out solar array idea is more complicated than I'd like.

I keep seeing everyone suggesting 15A, but why not 30A for shorepower hookup? I realize it isn't always available, but would it be really complicated to have both hookups available? Is there a major complication or cost change? Wouldn't 30A make it easier to pull power power when I am hooked up?

It sounds like the Dometic Penguin II is highly regarded. The Advanced RV Quiet AC seems to be available only as a retrofit through them and the price is pretty steep. It looks like I'm going to have to do some research and math to pick a winner.

 

[marklg]

Thanks for all the replies!

Just figured I'd note that I've lived in housing without air conditioning for a few seasons so I'm not looking to run the setup at 73F or anything, just looking to keep it bearable during peak hours. My van with the pup will most likely be parked somewhere near my job sites so I'll be close by just in case. I'd like to find a remote monitoring setup that could at least give me temp, battery capacity, and maybe even a webcam, but that's for another time.

I was already anticipating the need for around 1000AH of batteries. I figure if its really only necessary for the hottest hours of the day, and during heat waves where its like that all day I'll track down shore power. I imagine that would be easy enough to manage. I'm not interested in getting a generator and the fold out solar array idea is more complicated than I'd like.

I keep seeing everyone suggesting 15A, but why not 30A for shorepower hookup? I realize it isn't always available, but would it be really complicated to have both hookups available? Is there a major complication or cost change? Wouldn't 30A make it easier to pull power power when I am hooked up?

It sounds like the Dometic Penguin II is highly regarded. The Advanced RV Quiet AC seems to be available only as a retrofit through them and the price is pretty steep. It looks like I'm going to have to do some research and math to pick a winner.

You need to run the numbers before you spend on $10,000 worth of batteries.

15A at 120V is about 1.8 kW. 1000Ah of 12V batteries is about 13 kWh. With a 90% efficient big charger, it will take about 8 hours to charge those batteries with nothing else running. Without kW of solar or a second huge alternator and running the engine a lot, you are going to be limited. I think you will need 30A service to charge in a reasonable time but will also need a huge charger, which will also be expensive.

We have 400 Ah of batteries but use a generator for the AC, just not cost effective to do it any other way.

Regards,

Mark

 

[hein]

Our mach 8 9200 BTU A/C running off our 2800watt Magnum Inverter and 500Ah AGM battery bank.
We can run it for a while to cool off the van but not for all-day or all-nite use.

All the best,
Hein
DIYvan
541 490 5098

 

[1chewett]

"The Advanced RV Quiet AC seems to be available only as a retrofit through them and the price is pretty steep."
True, the price is steep but they will ship it to you for you to install. Hein was able to supply an adapter plate (thanks!), which made the install pretty easy. Haven't measured power consumption yet, but did measure it to be ~8-9 dB quieter than the one in our old class C. For my wife, the reduced noise level was well worth it.

 

[Kajtek1]

I'd like to find a remote monitoring setup that could at least give me temp, battery capacity, and maybe even a webcam, but that's for another time..

I am using http://www.lacrossealertsmobile.com/ WI-FI thermometers and weather stations.
Have several of them around the house to monitor the weather, pool temp and such.
When you have WI-FI it will send alert to your android when temperature exceed set criteria.
Thermometer cost about $40 and then you need cable module for another $20 if you have hard-wire modem.
Unfortunately the cheaper thermometer is not sending data at regural times.
Weather station works like a charm.
Other RV owners bet web camera and set regural thermometer in its view.
When this might serve dual purpose, you will not have notifications and IMHO automatic notifications will be crucial for your pet wellbeing.

 

[outbound]

....bare in mind ACs without soft start need like 20 amp peak, so even 2000W generators won't handle them.....

an a/c compressor will pull appx 3x run amps to start.
(run amps = appx 1amp per 1000btu capacity)

however, one CAN run a 10-12kbtu ac unit on a honda 2000w genset with one of these:

https://www.microair.net/products/e...rter-for-air-conditioners?variant=30176048267

i've installed a bunch of them and they DO work as advertised.

 

[Kajtek1]

I wonder why RV industry is not installing soft start at the factory?
It is not that RV are regularly hooked up to industrial- grade power supply.
I've been on campgrounds that at peak of the day would have 88V in the supply outlets.
When typical AC will run fine at this voltage, once it cycle off, the restart can be real struggle.
Would those thing be cheaper, I would install it on my house as well.
I do have evaporative cooler with 1 HP blower motor. Regardless 300 amp service, 2 electrical panels, when the blower starts, the lights will dim slightly.

 

[greatgoose]

I put in a Coleman Mach Cub. It’s low profile, and only 8k btu, so my Honda 2000 can run it if I can’t plug in. Works well enough in my 144 to make it tolerable if it’s hot