I HADDA DREAM! well an A/C idea

[Chip]

Mike and Danny,,, I agree with the easy way out and just use a conventional a/c ,, since there isnt a conventional unit in the 2000 to 3000 btu range was just thinking of an alternative thats inexpensive that would be lighter and take up less space than the window unit,,,, sure give me more room for pickle juice,,,, A well prepared camper has to have all the necissities,,,,

[toypusher]

I don't know anythinga bout AC units, but have wondered if a window unit could be take apart to seperate the componets and reduce the btus. 5000 is way overkill for me and the wife. She is really senitive to the cold with arthritis in her hands. Anyway, also thought it would be better way to build one into a tear.

[Curtis in Texas]

I just saw an advertisement yesterday for a small swamp cooler for spot cooling rooms. Let me see if I can find that add again.

Here you go. These are small, priced right and very portable.
http://www.compactappliance.com/Air-Coo ... ion=google>Air%20Coolers&utm_source=google&utm_campaign=Air%20Coolers&utm_medium=Air%20Coolers&utm_term=air%20water%20cooler&src=google&gclid=CM3IyKjqqpwCFSBN5QodQ0vpjA

This might be the ticket for your problem.

Hope this helps.

[ARKPAT]

Chip you can increase the BTUH by flowing water over the coils like LARGE Commercial cooling towers of the past did.





Pat

[Woodstramp]

Chip,

A couple of years ago my little bro bought a large horse trailer to take on trail rides. It was a large, metal affair that had a small camper section in the front. Only problem was that it had no AC and he and his wife could not swing one of those expensive top mount units. We just cut a hole in the wall and mounted a cheapo $99 Walmart 5K BTU window unit. When towing, the unit was pushed inside and a waterproof plate covered the hole. When parked, the plate came off and the little unit was slid out and plugged up. Worked great.

This pic is the same solution, just applied to a little TD. (excuse the artwork)

<img src="http://i591.photobucket.com/albums/ss358/woodstramp/ACideaforaTear.jpg" border="0" alt="AC idea for a Tear"></a>

[unforgiven]

hey chip, find a small upright freezer for your project, should work fine as frog's hair!!!

least that's my thunkin anyways.

but, as an aside note to all this cooling, it's C-A-M-P-I-N-G!! why are we all trying to bring the house with, when we are trying to non rough rough it?

lmao

but seriously, 5c.f. upright freezer!! look it up.

darryl

[Shadow Catcher]

I have adapted a 5000 btu window unit using 4" ducts that will plug into 4" deck plates on the side. This is in essence a super PetCool, (tried one not enough cool [208 cubic feet to cool]). This will be controlled by a Johnson Control digital thermostat inside the MM, which can also control the Pelonis heater. The control wire to the AC is through one of the ducts.

[aggie79]

I have adapted a 5000 btu window unit using 4" ducts that will plug into 4" deck plates on the side. This is in essence a super PetCool, (tried one not enough cool [208 cubic feet to cool]). This will be controlled by a Johnson Control digital thermostat inside the MM, which can also control the Pelonis heater. The control wire to the AC is through one of the ducts.

Shadow Catcher - Don't mean to redirect the thread, but can you say what model # Johnson Control thermostat you are using?

Thanks, Tom

[Shadow Catcher]

It is a Johnson Control A419 if I remember correctly.
http://www.houseneeds.com/shop/manuals/ ... lletin.pdf
It will be installed inside one of the front cabinets, thermocouple underneath the cabinet, with control line to the AC there is also a 110 outlet to control the heater inside. I cant tell you how many hours I spent looking for something like this.

[Ageless]

,,, sure give me more room for pickle juice,,,, A well prepared camper has to have all the necissities,,,,

Chip; that's why I have a pickup

[eamarquardt]

I kinda like the idea of using an a/c unit to cool a block of ice first and then cool the teardrop by melting the ice. Boats commonly use "cold plates" filled with brine or antifreeze in the "ice box" and cooled by engine driven compressors (just like auto air conditioning). By freezing the eutectic solution well below 32 degrees f you can have a freezer and reefer.

However I think that the amount of cold storage in a block of ice may not be worth the trouble and weight. Someone will have to try it and let us know how long the block lasts and how long it takes the air conditioner running to refreeze it. It might be an elegant simple solution to having cold throughout the night w/o running a generator or a/c unit with a noisey compressor as all that would be running would be a simple (and hopefully quiet) fan blowing air through the copper pipe or pipes in the ice/ice water. I'd like to hear the results of experiments or see calculations.

Given two people giving off 300 watts each, the approximate size of the tear, the temperature differential between the outside temp and the desired inside temp it shouldn't be difficult for someone to calculate how much ice would be required to go eight hours. My brother in law is a PhD rocket scientist (REALLY) and his specialty is heat transfer no less. I'll check with him and see if I can get some numbers to post.

Anyway separating a regular A/C unit into an external compressor unit and an internal evaporator unit wouldn't be that tough for a refrigeration tech. Just separate the components, plumb between the new locations, evacuate, and recharge. Piece cake if you know what you are doing.

For those of us that don't, I bought a 5K btu unit at Costco for about 60 bucks. I've taken it apart and it will be easy to modify so that you can duct the air in and out of it and into and out of a teardrop. In addion, the control head with the thermostat stuff is only connected to the rest of the stuff by 5 wires! Easy enough to add a couple of molex connectors or just hard wire an extension so you can have the basic unit outside and all of the orginal controls inside the tear. Depending on your choice the external unit could be mounted permanently to a convienent place on the exterior of the trailer or be set on the ground with the 5 control wires and power supply plugged into it. I personally think that having it detached from the teardrop would make things much more habitable inside the tear as most of the noise and vibration from the compressor would not be as noticeable inside the tear.

Fun to think about the options.

Cheers,

Gus

[Shadow Catcher]

One thing you need to remember is that control wires are from what I understand DC and you will want to go with at least 10ga wire.

[eamarquardt]

One thing you need to remember is that control wires are from what I understand DC and you will want to go with at least 10ga wire.

It doesn't matter if they carry ac or dc the current they carry is most important. Give that they are control wires, I'm sure that for the short distances we're talking about, if you match the existing gauge, that would be more than adequate.

Human body at rest little more than 300 btu per hour

http://www.engineeringtoolbox.com/met-m ... d_733.html

it takes 142 btu to melt a pound of ice.

http://en.wikipedia.org/wiki/Talk:British_thermal_unit

r value equals feet squared X temp difference in degree f X hour/ btu

http://en.wikipedia.org/wiki/R-value_(insulation)

Styrofoam is typically about r 4 per inch so lets assume our tear has 1 inch Styrofoam on all surfaces.

So heat loss/ gain is btu/hour=square feet X temperature difference in degree F/R value

typical tear 5 w X 4 high X 6 long equals

sides 4x6=24 x two sides = 48 square feet

ends 4x5= 20 x two sides = 40 square feet

top and bottom 5 x 6 = 30 square feet x top and bottom = 60 square feet

total= 148 square feet

If we want the inside temp of the tear to be 70 degrees and the outside temp is say 90 degrees heat loss/gain would be:

Btu/hour= 20 (temp diff in F) X 148 (surface area of teardrop sleeping compartment) = 296 btu/hour

So, under the best of circumstances we have 900 btu/ hour (two people sleeping in tear and the normal heat gain and not counting if the sun is shining or it is windy causing an increase in heat transfer).

So 8 hours X 900 btu/hour=7200 btu. 7200 btu/142btu/pound of ice=50 pound of ice required.

I think this is optimistic as there are many more factors that I can’t begin to calculate.

So, probably 75 pounds of ice will allow you to get a good nights sleep if the temp difference between the inside of the tear and outside is 20 degrees f and your tear has 1â€

[coal_burner]

Hey eamarquardt, you forgot the insulation in your math (that and some of your math got f'd up)
heat gain =t emp diff. x sft. x 1/rvalue
so heat gain = 20 x 148 x 1/4
20 x 148 = 2960 (you dropped the zero and got 296)
heat gain = 740 btu/hr
740(heat gain) + 600(people) =1340btu/hr
ice at 32f to water at 55f absorbs 1386 btu/gal
so 8 hrs at 1340 btu/hr needs 7.74 gallons of water (8.3 lbs/gal) frozen into a block of ice for proper cooling and dehumidification (that's why we stopped at 55 degrees)

When you use foam insulation, and your build quality is "exceptionally tight"(hvac code speak)you don't have to take wind into account.
you only have to take wind into account when you have gaps and cracks in your insulation envelope. if you insulate with fiberglass, you have to do a huuuuuge amount of math to get accurate numbers when your temperature difference exceeds 20 degrees. (hint for winter campers: r-14 fiberglass is actually r-10 fiberglass when the temperature is at 32 degrees).

disclaimer: this post was composed after the consumption of 11 beers

[eamarquardt]

Yeah, so what! Nobody is perfect. Actually, if you had been paying attention, you would notice that we both came up with about 50# of ice to cool and I added an extra bit for sunshine to get the 75#. So, my post contained a simple typo but my formulas were correct and my calculations were essentially correct and I came up with the same amount of ice requirements that you did. So there!!!!

Not bad for a person with an education in Biology, 5 years as a maintenance engineer in a paper factory, 20 years as a telecommunication engineer as compared to someone who appears to be a a/c technician or engineer!!!!!!!! However, if you'd like, when my brother in law returns to town (he's a PhD in engineering, Rocket Scientist at Rocketdyne, and his specialty is HEAT TRANSFER!!!!) I'll contact him and run the problem past him. I'm sure with his sophisticated computer programs he can give a more accurate SWAG (scientific wild assed guess).

Actually nice to have someone agree in my approach and come up with roughly the same answer. We must be on the right track. With some effort, someone could make a viable system that would be ultra quiet at night and "recharged" during the day when the noise wouldn't be that objectionable.

My disclaimer: I am DISABLED due to severe chronic pain

http://en.wikipedia.org/wiki/Neuralgia# ... _neuralgia

My presentation involves 10 nerves not just one as is typically the case. Also I have type 2 (continuous pain although it varies in intensity). Any lucid thoughts I have are purely accidental and according to AT&T and their prostitute doctors I am "fit for duty" in spite of my having been diagnosed and treated by the worlds foremost authorities on this disease. AT&T is now an evil company and routinely denys earned and promised benefits to sick and disabled employees. Give me a week or two and check out my new web site: www.attdisabilityscam.com.

If anyone has experience with Godaddy and would like to help set up the web site call me: (805)526-5277h (805)791-0287c or [email protected]. My name, phone, and address has been on another web site for over a year and I've never gotten a crank call or email but a lot of others that have been abused by AT&T have contacted me!!

Cheers,

Gus