AC expectations

I think what you were asking is how much more cooling are you going to get from your new 15K btu AC than your old 13.5K btu AC you replaced. I would say that given you have a second 13.5K btu AC already, you probably aren't going to notice any measurable difference. That is only a 5% increase in capacity and there are many other variables that can impact you well beyond 5%, such as the sun reflecting off a portion of the rig.

hmknightnc wrote:
About a 20 degree drop from outside ambient temperature is all you can expect

This is a commonly confused point with AC. You can expect about a 17~20 degree drop in temp from the input to the output of the AC. In other words the AC should drop it that much as it goes through it. The 20 degree thing is not between the inside and outside temps and a strong AC system should be able to drop the inside temps much more than that.

Keeping cool:
- Shade. Awning, slide awnings.
- Remove covers and check for obstruction in ac vents (sawdust, peeling duct tape, faulty installation)
- Keep the door closed: limit traffic, pets, kids in and out.
- Find and fill all those air leaks: corners of the slide, entries for pipes, vents, wiring, esp inside cabinets; old seals around outside storage doors.
- Foil window insulation (Reflectix): cut to fit, Velcro or may stay in place itself. In August, made an 8-10 degree difference in mine. While the trailer’s in storage, limits sun fading the upholstery. Blocks the view, though, and is bulky to carry around.
- window film (Gila, at HD, Lowes, etc.): Tedious to put on, needs 2 people, but once there needs no upkeep. adds some privacy. Helped ours enough that we no longer bother with the Reflectix except in long term storage.
- Small fan or two, esp for the bedroom and that favorite chair. With a breeze, and the AC removing humidity, 88 can feel pretty good when it’s 108 outside.

hmknightnc wrote:
About a 20 degree drop from outside ambient temperature is all you can expect

In the HVAC industry we don't measure the split from outside temps. The temp. is taken at the fresh air return (where it goes in) and then at the register. You should have an 18F to 20F split for optimal performance.

While my 27' 5er is new (probable operating a maximum effiecency)with dark tint thermal pane windows and the heavier insulation in the floor, roof and walls that Northwood Mfg. is known for...two weeks ago it was 110F here in Sacramento and my trailer maintained a constant 76F inside (with the shades closed and parked in the shade)....although it did cycle often througout the afternoon.

Keep the curtains shut during the day and (if possible) keep the doors closed on the bathroom where there's that big, heat friendly skylight.

It depends on your unit: our 38' 5th wheel had a 13.5 and a 15 and it would get downright cold if both were going full bore, even in the hot swamps of Ewe-stun.

Park in the shade!

tint all the windows limo. I did and it helps.

About a 20 degree drop from outside ambient temperature is all you can expect

So sorry I wasn't clear, we have a front AC at 13.5 and a rear AC at 15k btu.

To keep the FW comfortable you need 2 AC.