Air Conditioning Help Please!!!

[nds]

Hmm, my friend (boltos, also asking A/C questions here) just ordered a new Penguin for his 23' 1970 Safari (which hasn't had A/C installed before).

I'm assuming he won't have a problem with this unit cooling this smaller trailer? I saw another posT regarding bedrooms remaining hot. Is this more with the larger trailers or will he be needing to get a fan to circulate air back to his bedroom too?

[john hd]

"The owner's manual gives very explicit instructions to park the trailer in the shade, start the air early in the morning as it's easier to maintain a cool temp than to cool it down, use awnings, etc. etc. etc. All the stuff we already know. Basically, the owner's manual is telling me, in so many words, that the unit is inadequate to cool a hot trailer, but if you take all the right precautions it might be able to keep a cool trailer cool. So... now we know... "

roger,

my manual sez the same thing, common sense i guess.

i don't think that is particular to your trailer.



john

[drboyd]

...in terms of efficiency and overall comfort, believe it or not. Here's why: Bigger is Not Better

That's a great plan for the unit on your house.

The issue here is how RV units are used. First of all, most of the electricity used is not directly metered to the individual trailer, as I understand RV parks. (No experience whatsoever, so feel free to correct me here!) Second, trailer use is almost by definition on a temporary basis, so quick cool-down requirements should be considered.

Don

[85MH325]

Originally posted by drboyd
...in terms of efficiency and overall comfort, believe it or not. Here's why: Bigger is Not Better

That's a great plan for the unit on your house.

The issue here is how RV units are used. First of all, most of the electricity used is not directly metered to the individual trailer, as I understand RV parks. (No experience whatsoever, so feel free to correct me here!) Second, trailer use is almost by definition on a temporary basis, so quick cool-down requirements should be considered.

Don

For a fixed dwelling unit such as a house, I agree with the article. It presumes, however that the heating load is calculated as a fixed amount. With an RV, there is no attic, the insulation is only 2", and the sun can be relentless on a hot, sunny day without shade. So, the potential for varience is substantially greater in an RV than a house. The problem here is that the AC units mounted on a 34' trailer are just not up to the task of cooling off a hot trailer with constant BTU input from the walls, and unless you have the very latest AC units, a 30 amp circuit isn't enough to power two AC units on a single trailer.

So, as a practical matter the 13,500 BTU AC unit runs at max for hours on end, removing lots and lots of moisture, but is unable to cool the trailer as there are apparently more BTUs of heat coming in than the AC can cope with. Hence the advice from Airstream to park in the shade, use awnings, etc. etc.

Roger

[drboyd]

The real limitation here appears to be the service amperage per foot of coach length.

Given that water spots are BAD, we'd want to use distilled water, right? If a pound of water in evaporation absorbs roughly 1,000 BTU, wouldn't a couple of gallons (16 pounds or so) give you about an hour head start? (Assuming that it all evaporates, yada, yada, yada)

How about collecting distilled water from the condensate drain, and spraying the roof with it?

Now, I know what you'll say: Don, that's a lame-o/wacko idea, because when the unit only condenses significant amounts of water when the humidity is up, and evaporatively cooling the outside of the coach is thus markedly less effective under conditions of high humidity.

And you're right. Oh, well.

Maybe a couple of gallons of distilled water in the truck to give it a head start....

Don

[overlander63]

Roger, if your unit is only 13,500btu, why not upgrade to a 15K unit? I am not sure of price up there, but a 15K unit here in sunny South Florida is $499.00.
And, of course, since the one you have now works well, just a tad too small, maybe you could sell it to someone here on the list with a smaller trailer, and get at least part of your cost back.
It is just an idea, and would be better than buying a block of dry ice to put in the bedroom every night to cool it off.
Terry
(in Florida)

[Tomy Dean Noah]

Was in air conditioning for 15 years before retiring.
Rating for air conditioning is : regular airconditioning is for every 12000 btus is rated for 500sqft. ,,,, Heat pump 12000 btus , 400sqft. Most instulatins are under rated, because you must consider heat load== insulation, number of windows, airstream is metel, number of people, where parked. Most trailers have one of fiber class, when conpressed is about 1/8 inch thick ,with an r-vaule of about five.
If you install duck work in sealing, make the out put from the airconditioner curved so it will force the air through the duck. If it is at an 90 degree angle coming out , the turn is = to 25ft of duck. The curve is = to 10ft restricted static air pressure. The motor on the airconditioner is reated at so much cfm and static air pressure flow, that should be on the manfactures ratinf lable just inside the unit.
Anothe alternative is if you do not have tenting or very little tinting on the windows, you may consider doing this. Tomy