Whose or what fans do you use? I've seen some that say they will run up to a month on a C or D battery I believe and I've considered some computer fans on 12 volts, but don't know if they would like that enviornment.
I'm just starting work on a new frig/freeze in a day or so and regarding insulation it will have 4 inches on the side walls and 6 on the end walls and bottom with 3 inches for the top. Do you have 6 on all sides? Also I found one picture on your site, do you have more there?
We also have the oval evaporator (about 1/2 cu. ft.) that is a freezer and also cools the box. Anyone know what temps they have in the freezer section of one of these while keeping the box about 38?
Bob, congrats on getting on the new boat and getting on it
. We keep our frig on the Mac at 37-38, but if the batteries are in good shape (good solar day on the panels) we will run it down to 33-35 before night fall and we turn it off over night and it is usually 42-44 in the morning. We never had any food go bad on the 7 week trip doing this. I'll try and PM you about Ruth and when we will be down there and the other questions you asked,
Sum
Thanks,
Sum
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I used lifetime warranty computer box fans - the spillover is a 6", and the others are 1.5" - next to no draw. These should like this environment considerably, as heat is the enemy of computer parts. There should be less humidity in the boxes than outside, unless you're in Arizona or the like, too, typically no dust (look inside a computer, even at sea!). Very cheap on the internet. Because I'm a geek, I had some leftovers, so when one of the buck-fifty fans wasn't running (got submerged in the reefer during a leak in the gas at a connection - since rectified!), I just swapped it out for one of my spares. There are self-contained fans which run on 2 C or D cells, and they run for many months. They have the advantage of your moving them wherever you want. Mine are wired in; my doors have single-pole double-throw reed magnetic switches which turn off the fans, and turn on the lights, when a door is opened. So, when I open a door (or, as I see from what you've said, you would have just the single door), the cold air I'm trying to keep in the box isn't circulating.
I used 6" insulation everywhere, except at the hull. There, since it was an odd shaped space and I didn't want to have to build the box that way, I filled that with commercial 2-part foam, put in a bit at a time with a gun. The top level is 13" of expanded polystyrene. If there had been a notable return on investment, BTU transfer wise, I'd have made it even thicker than the 6" I stopped at in the rest of the box. Look up tables put out on the internet by Richard Kollmann to get the impact of having more R value. The only way to do better, and because of ingassining with a finite life (if you'll have the boat less than 10 years, it will be someone else' problem), you'd do well for making it somehow replaceable, are vacuum panel$$. They WILL get you a larger R value, and if combined with (encased in, with proper guards against possible puncture during manufacture of your box) your foam, you could do well above 30. Unfortunately, 30 is about the effective end of just foam. You have to get WAAY more space loss (by virtue of how much space the foam takes) to gain any significant R value.
Make sure there are no paths for air or moisture or heat to enter the box when it's closed, and do your very best to make sure as much possible heat is rejected. You can go to my gallery, and click on the very earliest refit pictures
http://justpickone.org/skip/gallery...r_Alterations_Work/00-2004-TheBeginning/12-04 - clicking any picture will either open a new gallery or enlarge a picture - to see what all I dealt with in my case. I was taking pictures of literally everything which was happening, but in the December 2004 pictures, while you'll have to wade through a lot of other stuff which was happening at the same time, you'll be able to see literally everything I did in the construction of our box, beginning with the removal of the old, and starting from the outside, building it in.
If this is a project in which you want to get long term value, I can't stress enough how important it is that you have 6" in all directions - INCLUDING the doors (which as you'll see in my pix if you go there, I had to engineer to make allowance for the swing) - and the doors should be double gasketed. Keeping heat out is the deal, and without as much help as you can give it, a lot will make it in. Every BTU you don't have to remove is amps in your batteries.
Good luck on your project, and keep us posted...
L8R
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