Looking for LOWEST BTU Roof A/C available-

Dometic used to make a 5k btu/hr rooftop unit to run off an inverter- I see they still make the 7K units, but they are "basement" units or split- they sell to the OTR trucking industry, called Dometic Cab Comfort. I see the new versions are called Dometic BliZZard.

I have learned that Coleman once made a "Mini-Mach" 7100 BTU A/C, but they are discontinued.

You are correct the LRA is the operative number to be concerned about, but most (not all) compressors LRA are somewhat proportional to their BTU rating, though as pointed out, some newer models have high BTU with lower LRA.

The newer Colemans are the subject to much discontent due to their extremely high noise levels (per the Casita Forum, as the new Casitas are equipped with the 9200BTU models that scream).

The 13.5 (Duo Therm) in my 2008 5th wheel will easily trip a 15a breaker while running on a hot day. The running current (after being successfully started) runs 14-16a until the interior temperature of the coach reaches 95 deg or under.

In AZ on a hot day (116deg ambient w/ 145deg temps parked on asphalt)I have to remove the CB panel and blow air on it to keep the breaker from tripping until the interior temp has decreased considerably.

I realize it's probably NOT a "high efficiency" unit, but it strikes me the lower the BTU output, the smaller the compressor, and all else being equal, smaller is easier to start, and it will cycle less frequently (fewer start cycles).

My search for a NIB or even used MiniMach has netted no results. I have an 8000BTU portable (on wheels w/ hose to discharge hot air outside) and the Honda doesn't even notice when the compressor cycles. I'd love that response from my genny.

My Casita has a Coleman 8300 BTU Mach that is OK, but the genny strains starting.

I wish the PO hadn't trashed the working unit my BigFoot came with (and whicfh is no longer manufactured). :(

MEXICOWANDERER wrote:
300 watts to run my laptop? Dang! I gotta be quick and unplug this sucker!

Yeah, that's definitely off. My laptop and speaker system use about 40-60w 12v dc. I didn't scroll down though, just posted it for quick reference for ac. But the more efficient a/c units skew the numbers, anyways.

I've been looking at split systems and 12v systems. These may interest the OP? Or maybe a window shaker installed on the roof, ducted in?

I got lucky and found a brand new Danby 5100 for $50, and installed it in its own duct system, but it really struggles once the temps get over 95F. I'll be adding some 12v fans to help with its fresh air and exhaust air movement. My camper's all metal, so that doesn't help either. The OP's unit is fiberglass? So that would help. But at those Texas Temps...

bobinyelm wrote:
I am looking for a power-miser roof A/C to replace my 13,500 BTU roof air the PO of my well-insulated BigFoot truck camper installed (throwing out the perfectly good OEM 7700 BTU unit).

He did it for "instant cooling" with hook-up campgrounds, but I want a unit that my little Honda 2000i genset can easily handle boondocking.

The smallest I can currently find is a Coleman 9200 BTU unit, so I'm hoping someone here may have an alternative.

Bob

IMO, you should be much more concerned about the LRA (locked rotor amp) rating, and not the BTU rating. The LRA rating determines whether your Honda EU2000i will start a given a/c unit.

A Honda EU2000i has the ability to "run" most 13,500 BTU a/c units---IF it could "start" them. Most 13,500 BTU a/c units only need approx. 10-14 amps to "run". Unfortunately, many of these same 13,500 BTU a/c units need 55-65 of inrush (startup) current to "start". The Honda EU2000i can output approx. 50 amps of inrush with the ECO mode on, and approx. 53 amps of inrush with the ECO mode off.

To my knowledge these two, latest generation 9xx series Coleman Mach Power Saver a/c units have the lowest LRA ratings of any 11,000 or 13,500 BTU a/c units on the market:

Coleman 11,000 BTU

Coleman 13,500 BTU

A Honda EU2000i will easily start and run the 11,000 BTU 482x7-9xx (LRA 41.5 amps), and has very, very good chance of starting and running the 13,500 BTU 482x8-9xx (LRA 50.5 amps) . . . with the ECO mode on.

Do not confuse the 9xx series with the previous generation Coleman Power Saver 8xx series. The 8xx series have a much migher LRA.

My two cents . . .

300 watts to run my laptop? Dang! I gotta be quick and unplug this sucker!

Texas is a little warmer and more humid, thus the need for cooling even in October!

Check with a camper dealership, and see where they get the 7,700 Btu one.

Good luck,

Fred.

It's not necessarily about the btu, I have the Coleman 9200 and My Honda eu2000 will run it but I did have an issue once. I believe there's a 13,500btu unit that actually draws less amps than the 9200 coleman. I went with the coleman because it was lower profile.

I have got my 13,500 BTU Roof Mount to start-up a couple of times but as soon as it cycles it trips the breaker...

We do bring along our 8000 BTU home window unit alot if we are going to be camping off the power grid for a long period in our OFF-ROAD Camper. Its works just fine from EU20001 generator. Our bigger problem is however not all the public camp grounds including the Natl Forest areas we go to allows us to use our generator after 8PM. Not much dispersed camping here on the East Side of the US.

I would almost think I could run the 9200BTU Coleman roof mount unit with my EU20001 generator... Maybe some others can dime in here on that model. They also make a roof mounted SWAMP COOLER type air conditioner as well but I have no knowledge of how they might work. When we lived in the Phoenix AZ area back in the 60s thats all the homes there hard on the roof. Had to fight off the Black Widow spiders to change out the filters haha...

About the only thing I use my 2KW generator for is to recharge my battery banks every morning and we run all the things we want to have on using an INVERTER or Direct Connected to the battery bank, Not having an air conditioner when camping off the power grid is not all that big of a deal for us.

Maybe you can find the original OEM 7700 BTU unit somewhere...

Roy Ken