Adventures in Air Conditioning - Danby 5,000 btu overhead install

gnudad2

Ok kids, this could be long.  
Also, I'm not an engineer, nor do I play one on T.V.   :-)
Having read all the posts about the Danby dripping and how to prevent it, I deciding to have a deeper look.  This is my quest:
I pulled the unit after a trip and silicone caulked all around the inside of the a/c compartment thinking maybe there was a crack or something.
Nope.  That didn't do the job.  Besides, there was little evidence of there ever being much condensate in the pan.  Drain was clear, too.
Next trip was high altitude in Co. where we dry camped for a week.  The 3-way fridge worked flawlessly on propane.....and we were dead-to-rights level.  No need for A/C.  This got me thinking, well, what if you want to use your fridge on propane AND your A/C?  One needs level, one needs tilting. Now I don't know to what extent being out of level will affect the fridge, but I'll leave that for others.  Point is, it got my mind going......not always a good thing.  Things break.   :-)
A/C Primer:   Air conditioners condition and cool the air.  Conditioning is pulling out the excess moisture.   This collects on the front (inside) coil and drips off and runs toward the back.   It's this water that is the problem.
Most window a/c units have what's called a slinger blade on the fan in the rear of the unit.  This is something I just learned.  Never came up on any forum discussions that I could find.  That's why I'm bringing it up here.  Anyway,  this slinger blade picks up the condensate (water) from the pan (bottom of the unit) and basically slings it at the coils in the rear of the a/c.  The affect of this is to increase the efficiency of the unit.... like perspiration on your arm.   NuCamp drills a hole in the bottom of the units to drain this condensate into their pan and out the drain.   Danby does not come with a drain hole because of the slinger blade.  BUT, as these units are installed inside, spraying water wouldn't work too well.
Now my theory is this:   The opening that the factory has cut for the a/c is plenty wide.....I assume they thought they were giving the unit plenty of access to outside air, plus the little computer fan up above the unit helps, too.  However the top and bottom of the opening encroach on the rear coils by about two inches.   Probably not significant until you remember the slinger blade.  I think, it's throwing condensate against the trailer wall at the bottom where it is able to end up running down past the factory pan and also any caulk, and down the wall onto the cushions........unless the trailer is tilted to the front and passenger side.  There is a bit of a moat formed in the metal pan that can hold water for the slinger blade and keep it from draining out the hole NuCamp drilled.
So there you have it FWIW.   And this why I want to put the a/c on glides and push it outside.  It will be way more efficient!

MuttonChops

gnudad2 said:
. . . what if you want to use your fridge on propane AND your A/C?

One needs level, one needs tilting. Now I don't know to what extent being out of level will affect the fridge, but I'll leave that for others.

My two cents, you are over concerned with the Fridge "needs to be level"  as user manual states:

Up to 3-degrees is a lot of front-to-end off level.
For a typical 320S Boondock with 15-inch wheels and a Coupler Ball Height of 16-inches if starting at 100% level you would have to drop the coupler by 5-inches to cause the Fridge to be greater than 3-degrees out of level.  For the A/C unit you only need a slight coupler lower than level to cause water to drain toward the A/C catch pan drain hole.

For Visual Reference, How 5-inches was Found.

Tabaz

Muttonchops - Whoa Dude!  That's scary smart.

gnudad2

@MuttonChops.
I understand.  Actually, most times when we'd be using the a/c,  we'd be on shore power.....as would the fridge, so the whole level thing is kinda moot.  But it got me to thinking about where these a/c units are leaking.  The biggest discovery was the raised moat around the rear fan and it clearly has gotten full of water.  The holes that NuCamp drilled are on the wrong side of that moat.  I submit that if one were to drill a few more holes in the moat area, 1) there's no water for the sling blade to pick up and 2) tilting the trailer becomes unnecessary when using the a/c.    I sincerely doubt the factory pan would overflow unless the drain is clogged.
But that's too easy.  I'm still thinking about glides. Lol

gnudad2

I should add that I'm probably using the wrong terminology.   What I'm calling a moat would better be described as a berm....an embossed, raised area like a speed bump, in the a/c's  metal bottom that meters the level of water to the slinger blade.  Holes drilled in this area would allow all water to drain into the factory plastic pan.
Ok?  Clear as mud?    :-)

Dutch061

Just want to point out that an "absorption refrigerator" needs to be level (within reason) regardless of the heat source. The coolant solution, which is a mixture of water, ammonia and hydrogen can pool and allow the sodium chromate to be exposed to the extreme heat. This dries the sodium chromate and causes it to have chunks or crystals. It is these chunks or crystals that plug the tubing and ruin the refrigerator.

The sodium chromate is to used for 2 purposes.

1. Increase the efficiency by helping provide a place for the coolant mixture to collect back as a liquid
2. Provide protection to the refrigerator plumbing from the caustic refrigerant mixture

Brad

gnudad2

Thanks for the info @Dutch061!  Always nice to know the "why" of something. Rest assured, we're never too off level, although I'm sure there are those who think I'm about half a bubble out, but that's something altogether different and probably not correctable!

Dutch061

LOL, I am more than half a bubble most days...

Brad

jalars8

Dutch061 - when you say the dried sodium chromate causes chunks or crystals which block the tubing and ruin the refrigerator, do you mean the refrigerator is not then fixable?  

Dutch061

When the sodium chromate gets "chunky" and plugs the refrigerator, they are trash. Sometimes taking them out and turning them upside down and flipping the around will dislodge the chunks but typically not. If they work again after flipping, they don't typically work as well and are usually not long for use.

With the advancement in compressor technology, batteries, and solar charging; it is of my opinion that the RV Industry a a whole should quit using absorption refrigerators. I have had 3 previous with absorption refrigerators and it seems like they were always too warm or they were freezing everything in the refrigerator, including the 2017 320-S we had previous to the current 2020 400 BDL with the compressor refrigerator. Funny thing is, when I bought the 400 the dealer had both. My main reason for not getting the larger refrigerator was that the 320-S was a pain in the butt to get the propane lit and I was just tired of fighting a refrigerator instead of enjoying myself. Going with the smaller compressor refrigerator ranks in the top 10 best decisions I have made, okay maybe the top 25. 

Brad 

jalars8

Ok.  How can I determine whether my refrig has gone chunky?  On a separate thread I detailed how my N180 (2018 320S) does not seem to be working.  I had, unthinking, started the refrigerator on shore power and left it on for several hours but was on a bit of a hill so not level front to back.  Not sure of degrees but probably more than 3.  After that when I have tried to run it, on the level, both on shore power and propane, each time after 8 to 10 hours or more, it did not appreciably cool.  But there is always heat at the exhaust vent (upper vent).  Outside temps have been in the 90’s.  I bought the 320 a year ago from a little old lady who swore she only used it 3 times.  

Dutch061

If the heater is working, observed by the fact that you get hot air out the vents but it is not cooling it doesn't sound very promising. Did it work previously before it was operated in an off level situation? Does it cool in any of the 3 modes, IE 120 VAC, Propane, or 12 VDC? I suspect not since you mention both propane and shore power. 

Before condemning it, I would consider having a trained and competent RV technician look at it.

Brad

jalars8

I am not sure if it worked before.  I used the trailer for one night a year ago after I bought it and don’t remember for sure if I used the fridge.  It doesn’t cool in shore power or propane modes but haven’t tried 12v.  I’ve assumed I’ll need to have it evaluated by a technician but hoped someone could give me a simple solution.  I appreciate very much the time you have taken and your information and suggestions.  Thanks.

BrianZ

Very interesting theory, @gnudad2.
So, are you going to test your theory by drilling those holes to see what happens?  I guess you'd need to run it in hot humid weather for a while to make sure you're getting the water dripping near the window, before you drill the holes & retest, while maintaining the same trailer leveling for both.  Let us know how it goes.

Dutch061

@jalars8, If you are going to try it on 12 VDC, make sure you are plugged into shore power. The extreme amp draw will drain your batterie(s) in a matter of minutes. My suspicion is that it didn't work when you bought it, which is one of the most overlooked items on purchasing a used camper. The reason is that it can literally take up to 24 hours for it to get cold once it is turned on. So most people ask, assume, or just take the risk; when you should have the owner turn it on and come back in a few hours. Unfortunately even though they are very simple in operation without any moving parts, they are stupid expensive!

I believe that a lot of people either replace with a compressor style refrigerator or use coolers when they die.

I wish you the best of luck getting it operational!

Brad