Building a "Mobile Home"

The insulation is really your issue. The better insulated the living space is, the less heating and colling requirements you'll need.

Basically to maintain temp within the living space, the capacity of the unit to heat or cool has to match the rate of heat transfer in (or out) of the living space. The greater the heat transfer, the more capacity heating or cooling you'll require.

To specifically answer your question in not possible with the information you've supplied. As you haven't given information about how much surface area, nor how it is insulated, therefor even though you've told us the temperature difference, we cannot calculate the heat tranfer (either in or out).

The best tip I can give, "Insulate the hell out of it" - this will minimise both the size of the heating and cooling and the power requirements to run it.

Hope this helps.

A small room sized air conditioner can be run from a power inverter and batteries, and charged by solar panels without a problem

If you are staying in one place, being as you are in africa, a decent set of ground tubes may provide enough cooling for you. I work outside, and i consider 80f cool enough for my home to sleep at night. You may ,too.

Some people prefer 60-65f in their home.

Shading the roof of your camper from the direct sunlight will greatly lower its inside temp, as well. Misting water on it will help cool it off as well, evaporative cooling principle. Give us the average humidity levels in your area, they matter in the math.

Give us some more numbers to work with, and a better understanding, mobile or stationary camper and i am sure someone in here could get you off to a good start.

HELLO, if he was staying in one place then he would not be building a mobile home, Duhh. I suppose you leave you mobile phone at home when you go out. I guess you get the picture at this stage.

You are so right!! GA.

Also he should consider the colour and reflectivity (at the frequency of heat/IR) of the outside surface so that the heats is reflected as much as possible.

Also, when parked (a white cloth "tent" should be errected to allow 25cm of space over the roof, so that no sun can directly impinge on the structure....of course if you cover it with Solar cells or similar, that may not be a good idea....though a Solar collector be mounted on one side and pushed out and up quite easily as both a shade giver and energy collector.

I do not think that you will be completely self sufficient with energy without a small generator though.....

Andy, I had in mind to paint the outside surface with an oil based brilliant white. The best of what is available. The "tent" idea is good and thanks for the 25cm. Will do. I have a very old freezer that works with "parafin". The cold produced by the heat from a lamp. How this works I don't know and what gas is used inside the elements I also don't know. But it works well. Would not the replacement of the heat source from gasoline to solar be an alternative?

Thats how Electrolux fridges work. My caravan fridge can cool using gas, 220VAC or 12VDC....

You need to look here :-

http://en.wikipedia.org/wiki/Absorption_refrigerator

Getting the heat to the right place may be a problem......

Great Andy! Will read through that link a few more times. Very cool. ;-) What caught my attention was the last line in History, about Adam Grosser's model. Would like to find out more about that. Seems that specific heating is not essential there.

See if anything we do here with our insulating coating would apply. http://www.ct-texas.com It keeps the heat out in the hot months and in during the cold months.

Recently we coated a refrigerated metal building in Texas. The owner said we dropped the attic air temperature 60 degrees. We have coated school buses, motor homes and refrigerated trailers with great success. I think it will help your situation as well.

Hal Skinner

Initially I thought this was just a spam post, but after an hour of googling your product, I think it has some merit. Moving paint internationally is always a pain, most carriers will not transport liquids by air. This fellow is in Africa...can you suggest a local purveyor of ceramic entrained paint? Or can you send him the dry ceramic powder for him to mix into a local water based paint of his choice?

Great idea Yusef! Keen on an answer - specially regarding the powder. If that could be done. Thank you.

I have a querry for shipping to Africa in to our shipping dept. Cant buy the ceramics to add in to paint. (there is a company that sells that stuff but it instantly voids the warranty of any paint you add it to, they dont say that).

It is our ceramic material that makes us different. We own the only company with the technology to produce it.

It might take a few days for the lady at the office to get back to me with the answer. However, if we can sell it to Russia, Mexico and China, we can probably do the same for Africa. At least, I would think so. I will know in a few days.

Hal

http://www.ct-texas.com

Thanx Hal. It might be your product that Bushriver referred to. Hear from you soon.

The shipping will not be cheap, neither is the coating. Just to speak up to a different post;

Our solar reflectivity is 83% (.83)

Our emissivity is 90% (.90)

What the poster was referring to is called the 'proprietary surface', in other words, whatever the outside surface is and it's reflectivity level, that is the reflectivity of the whole wall and/ or roof sysyem.

Increase the reflectivity level of the proprietary surface, less heat enters the wall or roof. THAT allows the other R-rated material to function on a greatly reduced temperature scale.

We raise the reflectivity of the wall or roof to 83%. Thats around 70% higher than most bare metals and around 65% higher than standard paint. We keepo the structure cool in hot months.

Where we stand out from other coatings is that we will also retain heat in the cold months. We are a very effective conductive heat barrier and a radiant barrier to heat flow. barrier.

Thank you all (and the guest). The roof will be going up in another day or two. I read the article on the paint and that should be the way to go but to get that paint in Africa would make an already expensive option double that. I do get the message! Before thinking about cooling or heating, I will be spending some time on insolation. Material is an problem because very little is available. A guy in town mentioned polystyrene sheeting covered with a "thin" layer of aluminum coated plastic tape to keep it in place. Thanks again for the advise, you set me off on the right track.

Insulation is not such a complicated thing as all that. I insulated a trailer by glueing an inch of styrofoam to the walls, and then glueing aluminum foil to the walls with spray adhesive to reflect the sunlight. It was an exterior application. The styrofoam by itself was not so great, but after I pasted on a layer of tin foil, it worked much better.

Yusef, we spoke about that today. Are you talking about normal commercial aluminium foil? Ain't that stuff to thin to be durable?

As far as heat I recommend Webasto. I used to have one of their small forced air diesel heaters in my old Chris Craft, The blower draws very little electricity (12v)

http://www.webasto.us/am/en/am_rv_heaters_930.html

VERY nice! Thanx!! I bookmarked.

Hi Boertjie

Great idea and all the correct answers above. There are guys Here in SA marketing ceramic reflective paint. It is a bit expensive but works very well. In our climate for mobility and economy of power requirements, avoid conventional aircons. I would go for an evaporative cooler that is 12v dc based. Waterpump from the boat/fishing shops like the guys use on the bass boats. Evap filter element from Munters, all built into the side wall of your home like a window mounted Aircon. Fan in the ceiling and you are done. Those little pumps and fan will work on solar panels and need +- 25lt of water to run on a hot day to keep you really cool and relaxed.

The other thing is to use a 2nd hand refrigerated truck body for you accommodation. There are people in the Cape that will make up very good caravan style windows for you as well, so that the thing ends up looking like a bought one not a maplotter (=trailer trash) special.

I would like to suggest you borrow or hire one to see what works for your type of camping/travel. If your wife enjoys, so will you, or you ford will become a very expensive garden ornament.

Let us know how it works out. Look me up via PM if you want some help with the designs.....cost you a beer or two.

Now is this the coolest or what!!! Can'o the best for you Bushdriver. Now things will definately heat up, or cool down. Catch you via PM. Thanx guys, I'm 100% sure that all off my problems will be solved now!! Praat jou Bushy.

I'm converting a very old Ford D0910 into a mobile home. Being in Africa with drastic climate changes (summer 45 Celsius and winter -10 Celsius), I need to get a system for both heating and cooling. The cooling is an issue. Q. Would I be able to set up solar power on 10 sq meters, to cool down a 30 cube/meter metal container. Outside temp 45 C, inside temp 21 C. How much heat and how much piping filled with what-ever gas to do this job.

• The equation used 30 years ago was Hs = 1.1Q delta T. IE sensible heat equals 1.1 times volume times temperature difference. Theoretical answer if I can work it is 792 for summer calculation. And no, I don't know what it means as I learnt in BTU's, square feet and fahrenheit.
  

• Gas used would have been R12 Check what is permissable. Now more likely to use R134A
  

• Copper pipe must be refrigerant grade, sealed and dry. Size around 1/4 inch - 6mm.
  

What I'd suggest would be to think of a EUTECTIC system. It doesn't use refrigerant, and would be more convenient with a solar array. It's other big advantage, can supply heat or cool by reversing connections.

Go to

www.southwest-solar.com

they are in Arizona and make solar evaporative coolers, they have sizes of PV and cooler and area cooled.

Note; swamp coolers only work in dry areas, I dont know exactly where you are or what the climate is like or where you plan to travel to so take it for what it is.

On the other hand in Louisiana where it is very humid the poor just put a large 6 foot diameter fan at one end of the house and it makes the whole house an evaporative cooler.

Spacecannon

There are two aspects of this problem. One is the irradiation and the other is the bulk conductivity. The ceramic or aluminumreflective paint helps with the irradiation. The bulk insulation helps with the conducted heat. If you have a room air conditioner that draws about 5-6 amps at 120 volts,(700 watts) you can power this with 10 square meters of 20% efficient solar panels (2800 watts max DC from 14,000 peak watts of solar input.

During the day the excess goes to charge a battery bank to run it at night.

Less efficient cells = more area needed in proportion.

The betteries will have to provide 700 watts for 16 hours.

A 12 V 50 amp hour(AH) battery will provide 600 watts for 1 hour, so you need about 20 or their equivalent. That is 10 24 volt 50AH or 5 24V 100 AH truck bettery, plus a 700 watt inverter to operate theair conditioner.

An absorption fridge operates from heat alone, and a typical one is 2 amps at 120 volts. They are notmade to pump much heat, just to run on fuel where electricity is scarce.

http://www.google.ca/#hl=en&source=hp&q=%22air+conditioner%22+%2Babsorption&btnG=Google+Search&aq=f&aqi=&aql=&oq=%22air+conditioner%22+%2Babsorption&gs_rfai=&fp=9d09cdefedea770f

The box must be made with 4 inches of closed cell foam insulation of the type purchased in blocks and cut to fit, or you can foam in place as long as the walls have the strength to resist the foam pressure. This bos is selaed. To get breathable air inside, you will need an air to air heat exchanging vent, so cool inside air exits and cools down fresh hot out side air as it comes in. These are made for RVs.

Herevare a few places to look

http://www.vent-axia.com/range/heat-exchange-unit.html

http://www.google.ca/#hl=en&safe=off&q=%22heat+exchanger%22+%2Bvent+&aq=f&aqi=&aql=&oq=%22heat+exchanger%22+%2Bvent+&gs_rfai=&fp=5c9e72a1248f3a98

Gratefull aurizon! The 20 batteries seems a bit "overboard" for my idea. I'm going to have a long talk with Duncan 0 he seems to be a "know-all" and will lead me on the way I'm sure.

A lot depends on the night duty cycle. If it is cooler in the less sunny time periods, that reduces the battery. If you can get one of those sun shade that you can unroll to shield the RV and use the solar panels erected above, that will also reduce the battery needed.

My rough calculation was for running 24/7, with sun for 8 hours and stored volts for 16 hours. Your budget and the weight are factors here. You may be happy for day cooling and forget the battery.

The most important thing is r-20 or more insulation and zero sunlight entry, with shades as well as reflective coating

In addition, if operated in a sealed box and the condensed water dripped outside, this lower humidity will reduce the need for night cooling. You can also make a larger solar panel and make ice in the day and run off the ice at night = smaller battery as well.

Hi Xboers

Hows that mobile home build going??