WeeRoll AC plans?

[usmc70_14]

Good afternoon everyone...

I have recently changed builder in terms of the trailer I want done. WeeRoll has won me over Cargo Craft....

I am getting a 7x12 V Nose with a 7' height.

Assuming I insulate (Foam Board) the roof and walls, what BTU window AC unit should I go with? I would like my temperature to be in the 70 'a at night and during the day 75. I'll probably be running a fan or 2 to move the air around the trailer. This trailer will be mostly used in South Florida, as you know heat and humidity suck major donkey ballz!

Since I'm building this to be my portable office with the vnose area being my desk area with monitors, where would you guys mount the AC Hatch for optimal performance throughout the trailer?

[flboy]

Good afternoon everyone...

I have recently changed builder in terms of the trailer I want done. WeeRoll has won me over Cargo Craft....

I am getting a 7x12 V Nose with a 7' height.

Assuming I insulate (Foam Board) the roof and walls, what BTU window AC unit should I go with? I would like my temperature to be in the 70 'a at night and during the day 75. I'll probably be running a fan or 2 to move the air around the trailer. This trailer will be mostly used in South Florida, as you know heat and humidity suck major donkey ballz!

Since I'm building this to be my portable office with the vnose area being my desk area with monitors, where would you guys mount the AC Hatch for optimal performance throughout the trailer?

8,000 BTU for sure... a 5,000 to 6,000 BTU maybe if insulation is really good all the way around. I am using an 8,000 BTU in a 7*18 with 2ft V that is 7.5 ft tall in Central Florida.. works great on hottest days. A 6,000 BTU did it, but struggled to keep a 20deg. differential on those days we got into the low to mid 90's with 80% to 100% humidity with trailer in full sun. Nighttime was no problem at any time.

I have double insulation in ceiling , ramp, and floors (2" thick) and 1" thick everywhere else. All well taped for no thermal bypass.

As far as mounting... up high and mid ship if possible for best results.




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[jwhite]

I have a 8000 also had a 5000 that just wasn't enough, I would rather have to turn it down than to suffer.
I like the fact after you turn it on after 30 minutes later it's feels great the 5000 would take all day to get right,But I like it cold if your only comcerned about the night time the 5000 might be ok

[usmc70_14]

Great advice... 8k it is!!!

Thank You

[McDave]

trailer will be mostly used in South Florida, as you know heat and humidity suck major donkey ballz!

Since I'm building this to be my portable office with the vnose area being my desk area with monitors, where would you guys mount the AC Hatch for optimal performance throughout the trailer?

13,500 btu mounted on the roof where it belongs. Do it once, Do it right.

McDave

[Newt182]

trailer will be mostly used in South Florida, as you know heat and humidity suck major donkey ballz!

Since I'm building this to be my portable office with the vnose area being my desk area with monitors, where would you guys mount the AC Hatch for optimal performance throughout the trailer?

13,500 btu mounted on the roof where it belongs. Do it once, Do it right.

McDave

I've wondered why everyone uses window AC units and not an actual roof mounted unit meant for an RV. Is it just because window units are cheaper or are there other reasons? Seems like the roof mounted solution would leave more room free inside as well, do they not cool as well or is there something else i'm missing?

[McDave]

It seems to be a budget issue, but by the time you have done all the work to install a window shaker and have to live with the loss of real estate and poor performance you could'a had a rooftop unit. Of course, once you have made choice you dig in in your heels and defend it, no matter what.

[onehoser]

if your window shaker craps out, you just run over to the nearest walmart. different story with the roof unit.

[jwhite]

another thing is I can run the window AC with a honda 2000 generator I have a extended run tank and it will run 24 hours before a fill up
my first camping trip my buddy had a roof top AC and he had bought a 3500 watt gas hog generator that needed to be refilled every 4/5 hours just to run the roof top AC
he was out there at 12 oclock = then 4oclock in the morning adding gas again at 9/10 adding more gas untill he had to go to town to buy more gas.

[Iconfabul8]

Window units are generally quieter. (Less noisy)

[flboy]

It seems to be a budget issue, but by the time you have done all the work to install a window shaker and have to live with the loss of real estate and poor performance you could'a had a rooftop unit. Of course, once you have made choice you dig in in your heels and defend it, no matter what.

McDave... wrong.. not a budget issue.. I could afford to buy a few rooftop units if that is what I wanted. It is 100% about the right size for the job and removing the humidity where I use the trailer the most (conditioning the air.. not just making it cold). 80%-100% humidity here in Florida and the AC needs to run more than 15 minutes to remove the moisture. And also, in my case, to run on a small 2K generator instead of at 3.5KW or larger Generator. Also would have needed to cut another 14*14" hole for a vent since the AC would have taken it up. The Vent will get used more than the AC in any case. I may have considered a rooftop if I could have got an 8K unit, but now that the window unit is in and works fine... a better solution since it can be replaced at about 1/3 the cost and not have to be taken anywhere to an RV center or etc.. Really doesn't take up much real estate where installed... just giving up about as much as a small cabinet would be and it is not out in the elements on the roof being slowly destroyed by UV's and being nested in by squirrels 24/7 even when not in use. Just sayin.

If they are not going to insulate and install properly, by all means, get a 13,500 BTU Rooftop unit and a large generator to run it boondocking. On a Large CTC over 20' or so.. probably would be fine also. Out West with almost no humidity.... it would probably cool and shut off and be fine since humidity is already below 50% (no damp cave feel)... not on the East Coast I can tell you.

Can you explain to me why the AC companies just don't put a 4 or 5 ton unit in a 1,000 sq ft. house so it cools faster? A lot of factors to include, insulation, how many windows, the climate, and etc. etc. go into the decision. 13,500 BTU on a 6*12 or 6*14 trailer in Florida creates a damp cave. Ask anyone who lives here. I'd think you'd know better than that. In your HVAC days, did you only sell one size unit? It is called Short Cycling. A real issue with ACs too large for job.

https://www.hydesac.com/air-conditioner ... ley-homes/

What is air conditioner short cycling?
Air conditioner short cycling is a problem in which your air conditioner goes through its on-and-off cycles too frequently. When this happens, it makes it nearly impossible for your home to stay comfortable and it can be a big drain on your energy bills. In addition, frequent on-and-off cycling can put your air conditioner through a lot of stress that can lead to breakdowns.

What causes air conditioner short cycling?

"An oversized air conditioner. If your air conditioner was not sized properly for your home, it might be too big. An oversized air conditioner will be too powerful for your home’s specifications, so it will blast your home with cool air and shut down quickly. This can lead to large temperature swings and will put a lot of stress on your system."

Note, there are other things that can cause Short Cycling, but those are the AC not working properly due to maintenance or etc..

[working on it]

It seems to be a budget issue, but by the time you have done all the work to install a window shaker and have to live with the loss of real estate and poor performance you could'a had a rooftop unit. Of course, once you have made choice you dig in in your heels and defend it, no matter what.

• Au contraire, many of us believe in just the opposite.
• Rooftop units work great for awhile, but later may become sore-points in older RV's, with limited repair/replacement opportunities (at RV dealers, Camping World-type operations), leaks from the unit or around the gaping hole in the roof (seal maintenance becomes more critical, when overhead), and always having to have beaucoups of power available to use them (30+ amps in parks, or 3500+ watts of generator power, for the common 13.5K btu units). With other types of A/C units available, those of us with smaller areas to cool, would rather use window units (permanently-mounted, removable, or "hacked" w/hose attachments), instead. There's no need to label the window unit users as low-budget, un-wise, heel-dragging individuals; but if that's what you think, then that's your opinion, and....
• I've used many window units, in houses, and only one rooftop unit in our 20-footer, but have known others who have had problems with their large RV units before. As I stated, they had to take their RV or trailer into a dealership, to get the problem fixed, whereas I can just take a couple of hours to grab another window unit at a big box or Walmart anywhere, install it, and have my house (or my TTT) cool again. Though my new house has central air, I kept three window units from the demolished house, JIC. And, though my over-complicated TTT 's A/C set-up may take awhile to teardown, I can install another unit there within minutes, if I simplified the exhaust routing (which I will, whenever....).
• Perhaps I might've considered using a rooftop unit, if I had a true, factory set-up (under warranty, of course), but even in a huge cargo conversion, I would've still installed one, or two, window units to do the job. Our hot, or hot and humid climate (for most of the year), would make me choose to permanently install the unit(s), but in an accessible way, for ease of cleaning/checking the seals/and possible replacement. All possible while inside the cabin, not overhead on the rooftop. Or even in a false bulkhead, removable in minutes, as others have done before. It's just up to the individual's creativity and workmanship, and skill level.
• But, choosing between rooftop or window unit, per se, isn't the only way to cool the trailer... there are several to choose from:
  1.) simple fan/vents - easiest to install, works everywhere, parts everywhere
  2.) "swamp" cooler (evaporative) - for hot, dry climates only, make your own or pre-made
  3.) window unit (permanent, or semi-permanent/slide-out mount) - DIY installed, replacement units available everywhere
  4.) "hacked" window unit - DIY installed, more fabrication skills needed, parts may not be readily available
  5.) Climate Right units- expensive $$ per BTU, parts/service/replacement ???
  6.) portable (roll-around) A/C units - not applicable to smaller TD's or TTT's (standies, retro canned hams, cargo conversions, OK), less efficient than window units
  7.) rooftop units - usually only for larger area cooling needs, not usually DIY-install/service (dealership/dependent)
  8.) mini-splits - hybrid between window unit and "hacked", or perhaps a portable?, expensive, never seen on a TTT (so far)
• This is just my opinion, regarding the never-ending debate. I only chimed in to express my counterpoint to McDave's seemingly omniscient pronouncement.

[McDave]

See what I mean? Heels dug in, Heads on fire. Here is a short tutorial on the causes of " short cycling". It applies to any geographic location and uses data to track the cause. The physics don't cease to be relevant because you live in Florida or any other location on this planet.
https://www.nrminc.com/blog/compressor- ... gy-waster/
While there are plenty of folks here who consider themselves experts in the field, few if any have ever had to prove it. That is to say make a living in the field, where results really matter. I have been there and done that, and I have no interest in steering you in the wrong direction.
Your call,

McDave

[onehoser]

another thing to take into consideration is that a roof top a/c may make the difference between getting your trailer into the garage or not.

[flboy]

See what I mean? Heels dug in, Heads on fire. Here is a short tutorial on the causes of " short cycling". It applies to any geographic location and uses data to track the cause. The physics don't cease to be relevant because you live in Florida or any other location on this planet.
https://www.nrminc.com/blog/compressor- ... gy-waster/
While there are plenty of folks here who consider themselves experts in the field, few if any have ever had to prove it. That is to say make a living in the field, where results really matter. I have been there and done that, and I have no interest in steering you in the wrong direction.
Your call,

McDave

Seems like your heals are the ones dug in. I just want folks to have all the information. I do not really care one way or the other what they choose to implement. I never claimed to be an expert... but I can tell you what does and does not work where I live by experience which seems to be backed by other "experts" who also make a living doing this.

This thread started out by USMC asking about what size window unit to select, not what form factor. You clearly stated he would be wrong to choose anything other than a 13,500 BTU rooftop. Sorry we had to go this route.

Good article, but they left off the parts about Shortcycling being caused by an oversized AC. The article presented appears to assume a previously well working system so omits the possibility for a poorly defined system which includes the target area to condition. The article is about diagnosis/failure, not system selection so I fail to see how it is relevant in this discussion. Just the facts.

I'd use a rooftop if it was the right tool for the job for the size trailer I have and could meet other design goals I have (power , maintainability, etc..) . You seem to think the rooftop is the only tool for the job even in a very small space.

https://www.hydesac.com/air-conditioner ... ley-homes/

Excerpt:

What is air conditioner short cycling?
Air conditioner short cycling is a problem in which your air conditioner goes through its on-and-off cycles too frequently. When this happens, it makes it nearly impossible for your home to stay comfortable and it can be a big drain on your energy bills. In addition, frequent on-and-off cycling can put your air conditioner through a lot of stress that can lead to breakdowns.

What causes air conditioner short cycling?

Note, there are many things that can cause Short Cycling related to maintenance and repair, But one thing than can also cause short-cycling is what? an over-sized Air conditioner?


"An oversized air conditioner. If your air conditioner was not sized properly for your home, it might be too big. An oversized air conditioner will be too powerful for your home’s specifications, so it will blast your home with cool air and shut down quickly. This can lead to large temperature swings and will put a lot of stress on your system." (and in a highly humid climate... will not keep humidity in check since it does not run long enough... whatever the physics, it is reality. )