T@B 320S Air Conditioner Hot Weather Testing

DougH

On the Danby to LG swap out I had to take out a vertical support on the right side and replace the horizontal support with another shifted to the right (LG is a little less high and a little wider).  Had to take a deflector to take cold air headed 45 degrees up and angle it a bit further straight out into cab. Also had to leave a gap to let cabin air get to back of A/C before compressor would just stay on (it was getting starved for fresh air).  So far it's now dropped from 90F to 78F in a half hour, but the sun is setting.  Next muggy / 100F day will be a better test.

CincyKid

I am going to try and take the NuCamp factory tour next week so that I can photograph the inside of area covered by walls, for future reference.  Good job here DougH, you increased your potential cooling by 15%!

DougH

And someone already mentioned to put a piece of foam on the underside of the box.  That plastic drip pan is the box bottom too and is a pretty hot radiator.  And the computer fan is much bigger than the vent pipe leading to the roof.  Would be tempting to get a smaller but higher CFM unit.  Between that and the poorly designed exhaust flow, I'm a little disappointed in the engineering of our A/C boxes.

CincyKid

SAM said:

@CincyKid, lucky for you, the forecasted high temp in Cleveland over the next 4 days is 76 F.

   Alas, I plan to be there starting Sunday afternoon through the following Thursday morning, will hopefully continue to be the kind of weather you mentioned.

CincyKid

Here are the results of my final testing of the AC System on the 320S with the Danby 5000 BTU Air Conditioner.  I am turning in my Freon pocket protector.   The question was asked "If you start the AC System earlier in the day will it prevent the trailer from getting too hot?"  I ran my test from 8:22 am to 7:43 pm and the answer is Yes if in direct sun, and maybe if in the shade. 

Once again my trailer was aligned East-West on my concrete driveway with the front window facing the rising sun.  The temperature near the ceiling at 8:22 am was already at 85.3F vs. an outside temperature of 79F.  At that point I turned on the AC full bore (exhaust fan On) with all windows closed and the Fantastic Fan off.  The data is plotted here and my conclusions below.

Conclusions:

(1) as the outside air temperature increased from 8 am to 2 pm the temperature inside the trailer at first dropped a couple of degrees, but then increased from about 82F to 89F (red line with diamonds) as it warmed up outside.  That is, the AC System could not overcome the direct sunshine on the roof and rising outside temperature.

(2) I noticed early on that the thermometer on the kitchen counter, exposed to direct sunlight, started to get hot in a hurry (blue line with yellow squares).  So at 10 am I realized the morning sun was streaming into the trailer and I closed the forward blind.  The kitchen counter thermometer immediately reduced in temperature.  What I took away from this is this "if your trailer is oriented at the campground so that the sun can shine directly onto that counter area you are well served to close the blind there.  Any side windows facing direct sunshine - do the same thing."  Makes sense right?  Even after closing the blind at 10 am the inside temperature increased not quite one-for-one for the increase in the outside air temperature for the next 3+ hours.

(3) Once the trailer was no longer in direct sunshine, but rather shaded, the AC unit could then truly get ahead of the hot temperature inside the trailer.  People have noted how well the system works at night when the sun is no longer heating up all that rooftop surface area.

(4) About 4 pm a storm front about 15 miles NE of my area started to cool off the area, and provide greater cloud cover.  Once again the sunshine directly impinging on the roof was lessened and the cooling system could then cool things down.

(5) In summary, given a choice at a campsite in the summer - get one with tree shade!  In winter get one without shade.  An alternative mentioned earlier in this thread is to get an awning to put up above the roof to keep direct sunshine off the roof - sounds like a real winner.

Storm about 15 miles NE at 4 pm greatly improved the cooling capability by increased cloud cover and 7-8 degree reduced outside air temperature.

Ratkity

All your data is very impressive! 

I must have been lucky and had my T@B facing a different direction. Friends of mine had a big rig (35') and their AC was barely making it when the outside temp was 110F (two or three years ago).

I did have all the shades drawn. It was comfortable in there for me, but I was lower down on the cushions. The air may have layered and I didn't notice it was hotter higher up. It was the worst day of the year if I recall! My sister was coming back from Canada after picking up her Alto. It works on a CoolCat type system which seemed to be working well for her teardrop as well. 

Thank you for all the effort you put into this! I would have gone for the fog machine too. I was just kidding about the incense, but I'm glad it worked.

DougH

You're right about the shade!  Today alternated between sun and rain clouds with the larger 6000 BTU unit running.  After an hour of 90F mild weather, but intense sun, here's a thermal pic from the floor near the door.   Cabin warmed to 78F. COLD air coming from AC and cooling the ceiling, bouncing off opposite wall, and heading back to a/c inlet... but waves of heat from closed porthole window in the shower on the right, lots of heat from closed overhead fan, and you can see even see every aluminum strut in the Azdel ceiling conducting the sun's warmth right in.   6000BTU can only get 8-12F cooler than outside when sun is baking, but 15-20F cooler when sun's not so strong.

CincyKid

@DougH was that an infared camera you were using?

DougH

@CincyKid Yes sir, an old Seek Thermal micro USB camera for smart phones.  Worked well years ago for fixing the stix & brix, but with all the updates to Android and newer phones with USB-C only works occasionally now.  I think they make some newer models.  All the thing could tell me this week is that the T@Bs need 15000BTU to stay cool in 110F direct sun.

DougH

And here's a better shot of the conduction from the ceiling structure later in the afternoon when the sun was on the a/c side.  Coldest area in scan was a thermos sitting on the table.  Wonder if the larger 400s have thicker / more insulated ceilings?  Wall didn't look as conductive.

atlasb

We had our 400 out last week for a couple days in the hot Oklahoma summer day.  When we set up the spot had the afternoon sun on the front.  We had been in the sun on the trip all day and it was 97 inside when we turned on the air.  I set the thermostat for 77 and it ran for several hours before it got down to 80.  The interior was heat saturated so like any other closed space, not only the air had to be cooled but everything else inside did as well.  Once we had it cooled down to 77 it stayed that way until I dropped it to 74 to sleep.  We used a light blanket with a sheet and were comfortable.  During the day we bumped it back to 77 and it held there.  The ambient outside air temp during the hot part of the day was in the upper 90's.  We had installed the heat vent deflectors with insulation behind the screen cover and use the fantastic fan opened partially, but not using fan.  Another thing is we leave the A/C fan speed on constantly and find that helps to moderate the temp inside.  If we do not leave the fan on, we find the cool cat cycles the A/C compressor on for short periods and we get up and down warm/ cool periods.  By leaving the A/C fan on low speed all  the time, we get rid of the temp up and downs. 

CincyKid

thanks for your feedback @atlasb

driftless

atlasb said:
  We had installed the heat vent deflectors with insulation behind the screen cover and use the fantastic fan opened partially, but not using fan.  

@atlasb do you have  pictures of the deflector installation that you could share?