Size AC unit in travel trailer

[William5829]

We just purchased a 2011 Rockwood 8315BSS and we want to buy a generator for our trip out west. I can't seem to find anything about the size of the AC unit in the paperwork in the trailer .It's probably a 13,5000 BTU but wanted to make sure before getting the wrong size gen set. Was going to call FR with vin number but they don't seem to want phone calls as there is none listed on their sites. Also will this unit keep the trailer cool we will go through Texas, NM, and Arizona in middle of August....I've read through most of the post and what a wealth of information they certainly helped us with the final phase of buying the trailer and now getting it ready for the trip.

[travelnutz]

Do the math, sorry, it's not an R-14 as built or there's a lot of holes open to the outside you can put yout fist all the way thru! Even if your trailer were a true vertical sidewall rectangular box it only has 1400 cubic feet total including the floor, walls, and ceiling thicknesses to the outside. You really mean a claimed R-14.

[Tequila]

Its a northwood. r14, but it was 110 out.

[travelnutz]

"In my current 25 ft trailer, the 13.5 had trouble keeping it cool when it was over 100 outside."

Tells you how poorly the insulation and sealing is on your small only 25' long trailer having 13,500 btu's of cooling. Why? 100 degrees is 30 degrees over a comfortable 70 degrees and you have 13,500 btu's of cooling. However, 70 degrees minus 30 degrees is 40 degrees and using only one 5,000 btu electric cube will easily heat a reasonably insulated and sealed 25' long trailer to way over 80 degrees any time anywhere. Make you feel cheated and lied to, doesn't it?

Kind of self-explanatory and tells you distinctly abd factually that the manufacturer is/was not being truthful in their claims of 4 season use and/or well insulated with normal expected comfort or interior temps in their RV product.

Many manufacturers resemble lots of the salesman, when their lips are moving they are lying. Same with the BS they print in their brochures with no certifications of actual thermal chamber testings and why do people simply believe them until they find out the terrible real truths later? Too late as you have already made the purchase and they made their bank deposit and you aren't happy! You must demand proof as to the true test results certified before you believe their hype as so few have ever actually tested the RV units they build as it's expensive and takes time and they know you'll never question their lofty claims. It really sucks and it's you who must live with the real facts, not them! 1 btu is 1 btu and 1000 btu's is 1000 btu's whether heating or cooling.

One BTU (British Thermal Unit) is the amount of energy required to HEAT or COOL one pound of water by ONE degree F.

[Tequila]

My honda 2000 will run my 13,500 at sea level to about 500 ft. I am getting the companion. In most cases i can simply pull one out and just the 2 to run air. My old rv had a 9200 btu a/c and a single honda had no problem. In my current 25 ft trailer, the 13.5 had trouble keeping it cool when it was over 100 outside.

[wmoses]

marcsbigfoot20b27 wrote:
Yeah I didnt mean it like lower quality per se, more like less insulation, air leaks, volume, etc.
I also forgot to add on the left side I have 3 mini awnings for the 3 side windows and I can actually feel the differece when inside if they are not open and blocking the sun. Its all the little things that add up.

True. We pull or day shades down and that helps a lot, even with the blackened window panes.

[marcsbigfoot20b]

wmoses wrote:

marcsbigfoot20b27 wrote:
This is also where insulation, dual pane windows or not, and trailer construction come into play.

In 90 degrees full sunlight with 75% humidity on the beach I can run my 13.5 on my 27 ft trailer down to 65 degrees or lower with no problem. This is probably because my trailer is very insulated.

If your trailer quality is lower the AC may have a hard time keeping up with the heat bleeding back in. In that case parking in the shade should help.

You forgot slide outs. Your RV has R8 insulation all round (mine has: R-7 Walls, R-12 Floor, R-14 Ceiling) but mine has 3 slide outs so there is more surface area. Also my windows are single pane.

So it is not a question of lower quality, just different construction features.

Yeah I didnt mean it like lower quality per se, more like less insulation, air leaks, volume, etc.
I also forgot to add on the left side I have 3 mini awnings for the 3 side windows and I can actually feel the differece when inside if they are not open and blocking the sun. Its all the little things that add up.

[travelnutz]

Yes, the average and cheap RV's are like having left the door open when heating or air conditioning. Poorly insulated and very poorly sealed for air leaks. The roof insulation is most important as approx 50% of the thermals are lost thru it. 25% thru the floor and 25% thru the walls and more if single pane glass. Throwing a second A/C at it is dumb when one A/C should be more than enough if you pay attention to "Insulation and sealing the Airleaks". One btu is one btu and it's up to you to buy smart and/or seal to maximize the efficiency. Real comfort and at far less cost, less drafts, less noise, and less aggravation.

A reasonably decent quality RV say 30' coach box length constructed, insulated good and sealed good but not even perfect with dual pane glass with a white roof and white sides (no dark colors or dirty/blackened roof) will not even tax a 13,500 btu A/C at 90 degree ambient outside temps and 70 degrees inside. Such an RV would have a max of 1680 cubic ft inside the outside exterior skins to cool. A simple cheap 5,000 BTU window A/C will easily freeze you out in a 10 X 10 X 8 foot room interior or building (800 cubic ft) in 90 degrees outside and would run the compressor less than 80% of the time.

2 times the 800 cu ft = 1600 cu ft and that's approx 10,000 btu's needed and you have 13,500.

Solar glass or white shades/curtains are a help also. White surface reflects and a dark surface absorbs and the last thing you want in the hot sun etc is absorption as it counteracts cooling.

Our 1991 36' all white Carriage 5th wheel with storm windows on the inside would freeze you out in 90 degrees temps in full Sun with the one 13,500 btu A/C set on the low setting. Really tells the story as to the true insulation and sealing on the RV! The cure for comfort in heat or cold an RV or home is really your choice when you buy or what you do to improve it after the purchase.

[wmoses]

marcsbigfoot20b27 wrote:
This is also where insulation, dual pane windows or not, and trailer construction come into play.

In 90 degrees full sunlight with 75% humidity on the beach I can run my 13.5 on my 27 ft trailer down to 65 degrees or lower with no problem. This is probably because my trailer is very insulated.

If your trailer quality is lower the AC may have a hard time keeping up with the heat bleeding back in. In that case parking in the shade should help.

You forgot slide outs. Your RV has R8 insulation all round (mine has: R-7 Walls, R-12 Floor, R-14 Ceiling) but mine has 3 slide outs so there is more surface area. Also my windows are single pane.

So it is not a question of lower quality, just different construction features.

[marcsbigfoot20b]

This is also where insulation, dual pane windows or not, and trailer construction come into play.

In 90 degrees full sunlight with 75% humidity on the beach I can run my 13.5 on my 27 ft trailer down to 65 degrees or lower with no problem. This is probably because my trailer is very insulated.

If your trailer quality is lower the AC may have a hard time keeping up with the heat bleeding back in. In that case parking in the shade should help.

[wmoses]

William5829 wrote:
....It's probably a 13,5000 BTU but wanted to make sure before getting the wrong size gen set. ... Also will this unit keep the trailer cool we will go through Texas, NM, and Arizona in middle of August...

Kind of late now to be wondering if the AC you have will be sufficient for the south. 😉

It all depends on:
- how hot and humid it is outside
- if you are in the shade
- how cool you like / can tolerate it inside.

I like it cool inside and find that with my single 15k BTU AC on my 30' trailer with ducted roof vents, I need the shade in 95+ deg.F humid weather. In open bright sunshine with no shade, the 15k BTU AC will struggle to maintain 80 deg.F inside. I like it at 75 deg.F or a little less.

Bottom line - in the summer you need to be under the shade, and that goes double if you have the 13.5k BTU AC.

[Bumpyroad]

zackyboy3rs wrote:

Bumpyroad wrote:
yes you can have too much AC. if too large it only runs periodically and you lose some dehumidification. should run most of the time when it is really hot.
'bumpy

In eastern NC when it is hot it does run 85-90% of the time. "I" can not have too much AC.

then I would say that you have an AC sized exactly right for your climate and size and construction of RV. how does it do on dehumidification when it is 99% humidity and 80 degrees?
bumpy

[biggrigg]

zackyboy3rs wrote:

Bumpyroad wrote:
yes you can have too much AC. if too large it only runs periodically and you lose some dehumidification. should run most of the time when it is really hot.
'bumpy

In eastern NC when it is hot it does run 85-90% of the time. "I" can not have too much AC.

You got that right!!!

[zackyboy3rs]

Bumpyroad wrote:
yes you can have too much AC. if too large it only runs periodically and you lose some dehumidification. should run most of the time when it is really hot.
'bumpy

In eastern NC when it is hot it does run 85-90% of the time. "I" can not have too much AC.

[wwest]

William5829 wrote:
We just purchased a 2011 Rockwood 8315BSS and we want to buy a generator for our trip out west. I can't seem to find anything about the size of the AC unit in the paperwork in the trailer .It's probably a 13,5000 BTU but wanted to make sure before getting the wrong size gen set. Was going to call FR with vin number but they don't seem to want phone calls as there is none listed on their sites. Also will this unit keep the trailer cool we will go through Texas, NM, and Arizona in middle of August....I've read through most of the post and what a wealth of information they certainly helped us with the final phase of buying the trailer and now getting it ready for the trip.

It isn't so much as just running the A/C as it is supplying the compressor motor startup SURGE current, especially for the subsequent restarts with head pressure.

Even non-inverter gensets that are always revved up to a fixed RPM often have problems with this. Since an inverter type genset may well be simply idling along when "hit" suddenly with a 3000-5000W A/C startup load they have even more problems.

Oftentimes the A/C motor's protective CB will cycle several times before head pressure declines enough to allow a restart.