Insulation Help ?

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Michael Cohn

I have a box on my h45, already installed (unfortunately), that I need to insulate on the inside. I cannot get to the outside without tearing out a LOT of furniture, and I have already drilled several holes in the furniture and shot 2 part foam around the box, which helped to some degree but not really enough. I now want to put insulation on the inside to reduce power consumption further. Vacuum panels are not a wonderful option, mainly because the inside of the box is quite complex in terms of curves and angles, and it would require many custom made vacuum panels ($$$$$), and because these are top opening boxes they would be extremely difficult to install. Heatshield Marine sells a 4 X 8 sheet of flexible material that would probably work, but I have heard both good and bad things about this material. Can anyone advise me about what I should do in this situation? Does anyone have experience with the Heatshield material or other materials that might work? Thank you! MC
 
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Dennis Brittain

Better insulation

Hi Michael, I used 'cheap' Dow Board used in house construction nowdays. Both Corning and Dow make the closed cell foam boards in 2" and 3" thicknesses. It comes in 2'x 8' sizing and has high R factor ratings for the thickness. I wrote a post on my installation a few months ago. Try looking in the archives for 'Freezer Fixes'. It has proved to be an incredible fix for the system! Easy to shape, high R factor, water proof and cuts run times in by half. Dr.B
 
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Phil Williams

Insulating

We have tested the Heat Shield material and found it to be about the same quality as polyurethane foam panels of the same thickness. If you really want to cut your running down the thing to do is to go to your local home supply company and purchase the foil backed 4 x 8 sheets of insulation material, earlier email response mentioned this, and cut to fit the panels of your box. Now this is the most important part. The foam panels must be covered with a water proof material to keep the insulation quality. I recommend using 1/4" thick sheets of PVC. It can be cut and bent to match the curve of the box. Once in place the corners can be glued to make it water tight. The best way to do this job is to remove the counter top first. I know this is a big job but you are better off doing it right the first time or not doing it at all. What kind of running times and temperatures are you getting now?
 
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Michael Cohn

Phil, to answer your questions...

With the SuperColdmachine, I've got run times of about 8 hours out of 24, with ambient temp of about 78 degrees, running box temps around 40 degrees at the top of the freezer side, and about 50 at the top of the frig side. I'm using a water pump and air intake and extraction fans in the compressor compartment. How the heck do you get that counter top off, anyway??? MC
 
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Justin Wolfe

Suggest you...

buy yourself a solar panel and save the aggravation. I've read every "insulation" thread that has come up in the last year or so. Adding insulation that is effective and longlasting has to be the biggest PIA on a sailboat, not to mention the cost which may exceed the cost of the refer. Buy a an extra battery or a solar panel or both. It just doesn't seem worth the effort. Besides 8 hours doesn't sound all that bad. What does the Super draw. 7.5 amps? That's only 60 amps per day. A decent sized panel could give you more than half of that. I seriously doubt better insulation will reduce your consumption by half. Just a thought...
 
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Phil Williams

Cost of insulating

Should you add insulation to your box? If it is a new boat the answer most likely is no. Most new boats come with sufficient amounts of insulation. To give you an example of what adding insulation will do for your amperage consumption I have done calculations on a 3.38 cubic foot freezer with various insulation thicknesses. The box with 2" of insulation will require 82 amps per day to maintain a freezer temperature of 10 degress. If we were to add 1" of insulation the daily amperage load would drop to 65 amps. If we were to add another 1" of insulations giving us 4" the daily amperage load would drop to 57 amps per day. Adding insulation is going to save energy. Can you get to the sides of the box to make it worth your while? In most new boats the answer is no. In older boats there was plenty of room to add insulation but today boats are built using CAD/CAM and this makes the fit much better and thus no additional room for insulation. So if you can not add insulation the best thing to do is work on your battery charging systems.
 
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Frank Walker

Insulate the Top

Michael, I have an older Hunter 30 that only had 1" of insulation under the counter top. I added two layers of 3/4" foil faced building polyurethane ($10 for 4' X 8')under the box top. Cut the pieces as necessary to get them into the box, glue them in place with silicone and finish off with some vertical grade Formica or equivalent. This vertical grade is flexible enough to get it in in one piece. Use cardboard to create a pattern. Glue it in place with silicone. Finish off the raw edges around the door with aluminum foil tape( avaliable at refrigeration supply houses for use on duct board). Caulk the edges with a water based silicone or similar product. Use a flashlight and a mirror to see. Not only does my unit not run as much, but the counter top no longer sweats. I have got my draw down below 50 AH per day on an old AB Cold Machine.
 
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