Does anyone make an A/C larger than 15,000 BTU

The ONLY answer in Texas Heat and Humidity is a 3rd AC on a 42 foot RV. There is NO WAY a 15k and a 13.5k will cool a 42 foot in Texas heat. ALL our RV's we sell over 40 foot have 3 AC units and my coworkers 41 foot DRV 5th wheel came with 3 15k AC/HP units and he has 4 slides and those units CYCLE and keep his family comfortable in 105 Texas heat. They are FULLTIMERS with 2 teenagers. Most of our 40 foot down to 36 foot have 2-15k units.
Last, a AC system does NOT have to run 100% to keep the moisture level and inside humidity down. A correctly functioning/sized AC system will cool most RV's and cycle. That may not happen during the 12 hours of the day at 100 degrees but will once the sun goes down. The BIG problem is what another poster stated---The INSTALL and how the gaskets and plenum system is sealed. ANY leakage will degrade the performance in hot weather and from MY observation, on systems that have the standard large return grill/filter in the ceiling, NONE are completely installed correctly. There is always room to seal them better. Doug

greenrvgreen wrote:
The simpler answer is a third unit, if you have an available roof vent. Also, don't waste your time taking the A/C in to be checked--it works fine, I'm sure. As other have said, there is a limit to what an RV A/C can do, particularly if it is ducted.

If I was in your shoes, here would be my thought process:

#1. Are both A/C units running on compression 100% of the time? If either unit is cycling, then you have TOO MUCH A/C capacity for the volume of your unit--or you have insufficient circulation of cold air in the cabin.

#2. I would check the ducting for leaks that are pretty much guarranteed to be there. If I really felt like fiddling I would tape the ducts up, or

#3. I would disconnect one or both A/Cs from the ductwork. Let them blow cool air directly into the cabin, and use a portable fan to circulate it.

#4. I would add the third A/C, if nothing else worked. IMO, the most important thing about an A/C is that it stays on compression 100% of the time. Don't give it the opportunity to pour wet, clammy air into the cabin. If you don't need so much cooling, turn the third A/C off and make the other two run 100%, and then turn the second off, leaving the first to run 100%. In my 18-ft TT I run a 6k (6,000) btu A/C for hours on end--and I stay away from Texas.

The master bedroom AC will cycle but not the main. I question how well the front AC pushes air to the rest of the unit since it is, in essence, trying to force air back down a duct that the main unit is pushing air forward. Of course it can cause the main unit to push more air rearward, but I don't see much cold air from the front AC actually cooling the rest of the unit.

Maybe the answer is 2 13,500 in the main area that can be controlled independently during hotter weather. I'd hate to give up my fantastic fan, though. Of course the other is to be happy at 76 on a hot day.

Forgive my ignorance here. Other than removing the distribution panel below the AC unit on the interior and checking the tape in the transition from the opening to the ductwork how does one seal other parts of the duct work since it is behind the ceiling panels? Should I remove the round vent grills in each room and check the transition from the duct work to the ceiling vents too?

TexasRedNeck wrote:
By the way, what is a basement AC? Is it like a ductless mini split for RVs? Never heard of that.

24,000 BTU with two compressors. Used in tall RVs where there is no roof clearance or it just fits better in a lower compartment. Ducting is in the floor similar to the furnace.

http://www.rvproductsshop.com/2ton-basement-airconditioner-w-hp-24-000-btu-46515-811.html

I know my 13.5 ducted roof air leaks into the ceiling because if I take an electric wall plate off there is positive cold air flowing out :R

They don't show net btu cap. 16/18kbtu must be gross btus. They're still pretty sorry ACs. 330 cfm isn't even enough cfm for an honest 1T AC. I'd like to know what the evap DT is and what the sensible and latent caps are. Craig

Terryallan wrote:

dougrainer wrote:
The largest is 15k. If your RV is longer than 25 foot, a 15k will not be able to keep up in temps above 90 degrees and hi humidity. Doug

Really? My 13.5, on my 29' TT, does a great job in the high heat, and humidity of a Myrtle Beach July day. (read 80% humidity, and 100+ degree F) As long as the doors aren't opening, and closing every 2 minutes, and in truth. The main door is always open, with the screen door shut. It has plastic sheeting (plexiglass) covering the screen. Maybe it's the superior insulation values of the AZDEL construction.

I think this is very subjective. I'd be content at 79 degrees in the interior where others in my family would say the A/C is not keeping up if it is not 74 degrees or less.

Our measures to keep the 34'5th wheel cool in 105+ weather is to put Reflective in the windows, awning out, and we put an Easy Up near the rear bedroom slide to minimize direct sunlight. We start early on the A/C, close the ducts in the master bedroom so more is directed to the living area. 105 is our threshold after that we stay home.

greenrvgreen wrote:
The simpler answer is a third unit, if you have an available roof vent. Also, don't waste your time taking the A/C in to be checked--it works fine, I'm sure. As other have said, there is a limit to what an RV A/C can do, particularly if it is ducted.

If I was in your shoes, here would be my thought process:

#1. Are both A/C units running on compression 100% of the time? If either unit is cycling, then you have TOO MUCH A/C capacity for the volume of your unit--or you have insufficient circulation of cold air in the cabin.

#2. I would check the ducting for leaks that are pretty much guarranteed to be there. If I really felt like fiddling I would tape the ducts up, or

#3. I would disconnect one or both A/Cs from the ductwork. Let them blow cool air directly into the cabin, and use a portable fan to circulate it.

#4. I would add the third A/C, if nothing else worked. IMO, the most important thing about an A/C is that it stays on compression 100% of the time. Don't give it the opportunity to pour wet, clammy air into the cabin. If you don't need so much cooling, turn the third A/C off and make the other two run 100%, and then turn the second off, leaving the first to run 100%. In my 18-ft TT I run a 6k (6,000) btu A/C for hours on end--and I stay away from Texas.

I can hardly wait to see Doug get hold of this one.

The simpler answer is a third unit, if you have an available roof vent. Also, don't waste your time taking the A/C in to be checked--it works fine, I'm sure. As other have said, there is a limit to what an RV A/C can do, particularly if it is ducted.

If I was in your shoes, here would be my thought process:

#1. Are both A/C units running on compression 100% of the time? If either unit is cycling, then you have TOO MUCH A/C capacity for the volume of your unit--or you have insufficient circulation of cold air in the cabin.

#2. I would check the ducting for leaks that are pretty much guarranteed to be there. If I really felt like fiddling I would tape the ducts up, or

#3. I would disconnect one or both A/Cs from the ductwork. Let them blow cool air directly into the cabin, and use a portable fan to circulate it.

#4. I would add the third A/C, if nothing else worked. IMO, the most important thing about an A/C is that it stays on compression 100% of the time. Don't give it the opportunity to pour wet, clammy air into the cabin. If you don't need so much cooling, turn the third A/C off and make the other two run 100%, and then turn the second off, leaving the first to run 100%. In my 18-ft TT I run a 6k (6,000) btu A/C for hours on end--and I stay away from Texas.

WOW. I opened a can of worms. For the record it is a 2 month old 42 ft fifth wheel and has 2 ACs, a 15K in the main area and a 13,500 in the master (it is a bunk house model) The 13,500 cools the master like there is no tomorrow when I set in on dump. Both units are ducted in the duct work. Granted I'm one of those people that aren't happy if I can't acheive 72 degrees inside no matter how hot it gets. No offense to anyone outside of Texas, but unless you've been here in the summer, your reality may be a bit off (OK, some southern Louisiana and Florida folks may get a pass)

I know all the rhetoric about 20 degree drop, yadi yadi, but if you have enough money you can get square baseballs, right? the service is 50 amp and a few extra amps won't kill the system.

I am going to have the 15K unit checked out since I don't percieve the temp drop that I think it should have (only comparing the temp of the air coming out of the unit), but it may be because the incoming air is warmer since the kitchen/living area is so much larger than the master area.

I love this forum and appreciate all the comments, input and feedback, even if you think I'm crazy for wanting it 72 inside when it is 100+ outside.

Of course the other option is a third AC, but the simple answer would seem to be a larger main unit.

By the way, what is a basement AC? Is it like a ductless mini split for RVs? Never heard of that.

Oh and the duct leakage may be a valid concern ( I am amazed at the workmanship - or the lack therof -for 50K) however I'm commenting on the ability to cool the main area when dumped not ducted.

pnichols wrote:

MEXICOWANDERER wrote:
... It boiled down to having crummy insulation ...

That's just about the bottom line.

Folks seem to pay way to little attention to this when shopping for an RV, whether new or used, and then struggle afterwards to try and work around it. Above "average" insulation and parking in the shade are the two best solutions. I'll bet it's an American RV manufacturers' issue ... I wonder how well the run-of-the-mill Australian RVs are insulated?

Few people are going to pull the lower cover and the registers when shopping to see if everything was installed correctly. Unfortunately, they depend on he manufacturer to do that. One thing for sure, to not upgrade a single AC trailer to 15KBTU is simply nuts. Even if you think you don't need it, you don't know where you might end up, and you don't know where the next owner is going with it. Skimping on that $146 upgrade may cost you a sale, not to mention some comfort in hot weather.

Dometic makes a marine version of an 18K BTU AC with almost the same footprint, weight, and power consumption of a 15K. The difference is that these units are water cooled and I don't know if the size of an air cooled condenser at that size would be problematic. I would certainly be leery of the Chinese knock-offs that claim to do more for less.