Looking for LOWEST BTU Roof A/C available-

[bobinyelm]

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

[bobinyelm]

Yes-

That spec sheet is for the 3PS via the link from another poster.

The specs for the 11,000 BTU 9XX Series Mach 1 you mention is:

Mach 1 9XX Specs

This is lower then the 3 so-called "Power Saver" units.

It would SEEM that my Honda 2000i might run it based on the specs-

These are the specs for the new 9200BTU Polar Cub Casita installs:
Polar Cub 9201 9200 BTU Specs
but many Casita users say their Honda 2000i struggles to start that one (plus due to higher fan speeds for use with R410A it's objectionably noisier than the OLD R-22 Polar Cub Series).

Strange that it is 9200 BTU in the 9XX Series you mention (and makes me wonder why Casita doesn't install the Mach 1PS instead), but the LRA is HIGHER (45.6) vs. the 11,000 BTU Mach 1 LRA at (41.5).

Confusing!

But Click Here is a thread where someone with a truck camper tried using the Coleman Mach 1 PS 11,000 BTU unit you suggest, and it worked fine (at cold temperatures) with a Honda 2000i genset.

I mention that because I noticed that my 5th wheel A/C uses OVER 15a at hot temps (116 deg ambient, but more like 145 deg on asphalt) and tripped its 15a breaker running, yet when the inside air cooled to the 80's (after the A/C had been running a long time) the unit was only drawing around 12 amps. (I've learned carry a clamp ammeter w/ me at all times).

The only way I could keep the breaker in was by pointing a fan at the CB panel until the A/C had cooled the RV interior down a lot. The coolest I could get it it in my 5er was about 87 degrees at the hottest part of the day, but that was AZ parked on an asphalt RV campground lot, a pretty extreme condition which I mention only because A/Cs take a LOT more current in high ambient temps (The Coleman chart in the link shows 25% more in desert conditions, in fact) .

[jrnymn7]

I hear ya.

I'm a Tinsmith, so duct work and air handling is what I do. So, for me it would be a piece of cake. In fact, I modded a mini-school bus, so my particular skills and experience came in very helpful.

Yes, a rear window install may be best in your case. I basically re-created an outdoor environment, inside the bus, by building one exhaust and two fresh air plenums. But in the extreme heat, there's too much heat build up, so I need to install three 12v fans to assist with air flow. But with a window install, you won't encounter such issues.

Nice little camper, btw. I sometimes wish I went that route.

[otrfun]

bobinyelm wrote:

dahkota wrote:
Coleman Mach 3 p.s.

The Locked Rotor Amps is pretty high for a Honda 2000i, and the running wattage is awfully close to the max wattage to the max for the genset, which I'd like to avoid.

Mach 3 PS Specs

These specs are for the older, discontinued, 8xx series Coleman Mach Power Saver. The newer 9xx series have much lower LRA/running amps (see my previous post for the 9xx series specs).

[bobinyelm]

dahkota wrote:
Coleman Mach 3 p.s.

The Locked Rotor Amps is pretty high for a Honda 2000i, and the running wattage is awfully close to the max wattage to the max for the genset, which I'd like to avoid.

Mach 3 PS Specs

[bobinyelm]

jrnymn7 wrote:
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...

I looked up a "Danbi5100" and it appears to be a window unit (of which I have 2 similar nearly-new units). My truck camper is pretty tall already, and adding another 18" and cobbing together some sort of way to tie it into the 14" square hole in the top (on which the roof unit is currently installed) doesn't sound like a really good plan.

To be honest. mounting it in the wall at the rear through an enlarged window opening Picture Link sounds preferable, though I really don't want to butcher my back wall, either, unless I could somehow make it interchangeable with an attractive rear-window for non-summer use.

I wish there were a similar unit made in a low-profile ceiling configuration, though the probable low volume of sales would make it uneconomical to manufacture, I guess.

[jrnymn7]

This may stir up some creative juices?

http://www.youtube.com/watch?v=IHDT5ZEpKkw

[Chris_Bryant]

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.

[bobinyelm]

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). 😞

[jrnymn7]

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...

[otrfun]

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 . . .

[dahkota]

Coleman Mach 3 p.s.

[MEXICOWANDERER]

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

[jrnymn7]

http://www.hayesequipment.com/honda_generator_wattage_guide.htm

[Golden_HVAC]

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.

[hedge]

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.