Building a Reefer Box with Aerogel

[SV Demeter]

Originally Posted by Celestialsailor

The box mounts under the counter-top with angle flanges from within the box. There is an exposed area at the back of the box where an insert of insulation is attached. The lid ic Corian with insulation also.

Can you explain a little further? For the liner you made the bottom and 4 sides off a mold with gelcoat and glass. The top of the liner has the outward facing flange. Your countertop is corian. Im lost as to how you insulated the countertop and what costituted the inside top of the liner? How did the inside top of the liner bond to the rest of the liner, ie the flanges?

Any more photos?

[Celestialsailor]

Originally Posted by SV Demeter

Can you explain a little further? For the liner you made the bottom and 4 sides off a mold with gelcoat and glass. The top of the liner has the outward facing flange. Your countertop is corian. Im lost as to how you insulated the countertop and what costituted the inside top of the liner? How did the inside top of the liner bond to the rest of the liner, ie the flanges?

Any more photos?

...Ah...I see the confusion. The outward flange you see in pic 3 is so after the aerogel is attached, an outer skin (1 layer of mat) can be added and attached to that flange to totally encapsulate the Aerogel. If you look closely in that photo, you will see there is also an inner flange which is used to hold it up under the counter which is wood. After it is installed I will add insulation over the inner flange to add an R value under the counter. Of course the lid will be insulated also covering the top of the box. I will take more pics as the project goes along.

[SV Demeter]

This weekend I was able to finish removing the old ice box and insulation. Below are some crappy photos from my phone. I need to decide how to start building the new box. Im thinking of using a piece of plywood to square off the bottom and then layering in the aerogel and taping the seams. My plan next was to use blueboard foam to build up 3" of thinkness and then laminating a liner of FRP to the foam, filleting the corners. Suggestions?

[SV Demeter]

I guess another option would be to find a drop in top loading fridge like the CB-110 here: http://www.dometic.com/e330b048-89bb...4137a70c.fodoc

I think it might fit but Im not sure if its the best use of space. Are there other top loading drop in fridges I should look at?

[osirissail]

In the area of easily available (i.e., Home Depot, Lowes, etc.) insulation materials to build a frig/freezer for a boat - -

Here is a listing from Wiki - Building insulation materials - Wikipedia, the free encyclopedia
Go down to Categories and you will find Vacuum Panels (best), aerogel (next best but not easily available),
polyisocyanurate (next best and easily available) and polyurethane panels (good and easily available) and their R-values per inch.

Two very common materials I have used are the "R-Max +" foil faced boards (Polyisocyanurate) which are great at about R=6.5 per inch. And the foil facing supposedly helps.
http://www.rmaxinc.com/downloads/DataSheets/rmp3.pdf

Then the "Blue Board" which is now colored pink so it is now "Pink board" and an average R=5 rating.

From: Insulation types
"Rigid Board Insulation
Common Name(s): Polyisocyanurate, polyiso board
R-value per Inch: 6 - 7
Strengths or Best Use: high R-value, readily available at local stores, easy DIY installation, can be airtight if sealed/taped at the seams, good for narrow spaces that still need high R-value, air can go around but not through this insulation
Weaknesses: Expensive, R-value diminishes slightly over time especially if the foil face is removed, will absorb moisture if wet, degrades in sunlight

Common Name(s): Extruded polystyrene, XPS, blue board, pink board
R-value per Inch: 5
Strengths or Best Use: readily available at local stores, easy DIY installation, can be airtight if sealed/taped at the seams, air can go around but not through this insulation, used for foundation insulation and under concrete slabs
Weaknesses: degrades in sunlight, some ants will burrow and nest in XPS, not very fire resistant."

Finally, there is the poured 2-part foam which can be a bitch to work with but will fill those left-over curved parts of the hull or other barely accessible areas. Because of its nature to expand spherically there are large "unfilled" areas left in the area. So it is not very good as a primary insulation material, but works will for providing backing support or filling "dead-zones."
"Common Name(s): Kit foam, can foam, DIY foam
R-value per Inch: 5 - 6
Strengths or Best Use: can be used to fill cavities or to fully insulate small areas, available for DIY but not necessarily user friendly- some learning curve and requires special respirator filters, available by mail order anywhere
Weaknesses: expensive especially if used for large quantities, not user friendly- requires know how to both select right product and install it properly, DIY USERS MUST STUDY UP- improper installations can lead to poor mixtures that don't cure or to pushed walls, subject to minimum and maximum temperature restrictions during installation."

[SV Demeter]

I was planning to use a combination of Aerogel and Blue board. Hope to avoid the spray foam but may use in small quantities if needed. "iso" from what I hear is not so great long term in a marine enviroment as it absorbs moisture and r value degrades. Im more concerned at this stage with box building techniques.

[janders]

We just got done with our fridge. I was building a new 4.5 cu. ft. box in place of an old 11 cu. ft. box so I had lots of room for insulation. I used XPS (blue board) insulation just about everywhere because it's better at resisting moisture. Plus, XPS is much easier to cut and shape. Polyiso was a giant pain to cut to size. Here's our blog entry on insulation:

s/v hello world: fridge insulation

The box construction was pretty difficult because we couldn't remove our counter top which meant we had to build the box in place. I used 1/2" marine ply and then fiberglassed over the top of that. The really difficult part was finding a food safe finish. I've talked to quite a few people who've finished off the interiors of their fridges with gelcoat, only to have their cheese and milk taste like gelcoat for the next year. I ended up using epoxy with white pigment mixed in. See this blog entry for more detail:

s/v hello world: fridge box construction

The final result:


More photos here:
Fridge Box Rebuild - hello world! | SmugMug

[SV Demeter]

Originally Posted by janders

We just got done with our fridge. I was building a new 4.5 cu. ft. box in place of an old 11 cu. ft. box so I had lots of room for insulation. I used XPS (blue board) insulation just about everywhere because it's better at resisting moisture. Plus, XPS is much easier to cut and shape. Polyiso was a giant pain to cut to size. Here's our blog entry on insulation:

s/v hello world: fridge insulation

The box construction was pretty difficult because we couldn't remove our counter top which meant we had to build the box in place. I used 1/2" marine ply and then fiberglassed over the top of that. The really difficult part was finding a food safe finish. I've talked to quite a few people who've finished off the interiors of their fridges with gelcoat, only to have their cheese and milk taste like gelcoat for the next year. I ended up using epoxy with white pigment mixed in. See this blog entry for more detail:

s/v hello world: fridge box construction

The final result:


More photos here:
Fridge Box Rebuild - hello world! | SmugMug

Nice post. How long have you had the new box in operation, does it perform better than the old one, if you had to do it over wehat would you do differently?

[janders]

Originally Posted by SV Demeter

Nice post. How long have you had the new box in operation, does it perform better than the old one, if you had to do it over wehat would you do differently?

Thanks!

First off, the old fridge was a giant AC compressor/cold plate system running off a 2kW inverter that drew 60 amps () out of the batteries every time it ran. Our previous owner budgeted 140 amp hours/day just to run the fridge. It was also a really big box at 11 cu. ft. The year we were out cruising we went without a fridge because we didn't want to run the engine or a generator just to run the fridge.

We love the bejeezus out of this new fridge. Because we cut down the volume to 4.5 cu. ft., we had a ton of room for insulation. I spent alot of time ensuring the insulation we put in was air tight and protected from moisture entry. I don't have efficiency metrics on it yet. One of my remaining tasks is to finish wiring up an hour meter to the compressor so I have hard data on the compressor duty cycle. Once the hour meter is up and running, I'll post the results on CF. Water temps in Seattle are 45F so we're not really going to stress the fridge until we get back to Mexico. Then I'll find out how good of a job I did.

In terms of what I would do differently? Knowing what I know now, I might not even take on the job. It took probably 8 months of effort working nights and weekends on a boat we were living on at the time. However, the biggest difficulty in our project was building the box in place. If we could have built it off site and dropped it in, it would have been orders of magnitude easier.

I would say the decisions I made right were:

• Installing a 1 cu. ft. freezer bin. It's the perfect size to make ice, hold a container of ice cream and maybe a couple fillets of salmon.
• Making the new box 4.5 cu. ft total. It's small enough to be efficiently cooled by a single air-cooled 12V compressor.
• Using pigmented epoxy for the finish. There is zero smell coming off the epoxy finish. And once I learned how to finish it to a gloss, it came out pretty nice.
• Going with SeaFrost for the compressor and freezer bin. Awesome service. Really helpful.

What I would do differently:

• Pigmented epoxy doesn’t have much opacity so I had to put a **** ton of coats on to get coverage so you couldn’t see the colors underneath. Especially because I was using white. Next time, I would mix the white pigment into the epoxy I was using to lay up the fiberglass. That would give me a whiter background so I could put less coats of pigmented epoxy on to finish.
• I spent a ton of time finishing areas you can’t see, like behind the freezer bin. Dumb.
• I did not do a good job of dry fitting the lid insulation to the lid ledge and ended up having to finish the lid insulation twice because of that mistake. Dumber.

I just finished a blog entry on the lid construction. You can check that out here:
s/v hello world: putting a lid on it

[Weyalan]

We are just at the closing stages of a similar project.

4.4 cubic foot total cold space, split to approx 1.4 cubic foot freezer space / 3 cubic foot fridge space.

Isotherm 12V air cooled compressor (BD 50) driving a 32" x 8" cold plate

We used Aspen Aerogels Spaceloft for our insulation. We aimed for 3.25" of insulation... which sounds like a lot, given the R value claimed on the material, but when we calulated the size of the box we and the space we had to fit it into, that's how much space we had to fill... I'm always a little teeny bit sceptical of the claims of the manufacturer, and there isn't really any such thing as too much insulation...

We used 4mm marine ply for the box. We bought an 8' x 4' sheet of ply and laid fibreglass on both sides (R180 epoxy resin) before cutting out the panel. We glass tabbed the box together externally before fairing and coving with epoxy / microballons internally and spray painting up with 2-pack epoxy paints. The divider between the freezer and fridge is extruded polystyrene 1.125" thick with epoxy glass on both sides.

[kefroeschner]

Has anyone thought of or tried the stuff called "Reflectix?" It is available in hardware stores and is a multi-layered combination of some Al coated plastic film (aluminized mylar?) about 0.5" thick in a flexible roll. It is mostly air space between the layers of al-mylar and is normally used as insulation around engie compartments etc. I do not know the R factor but we used something similar a long time back to keep a nuclear device cool at the bottom of a very deep and hot hole and it worked well.

I am thinking of trying this as a liner, three layers, in our ice boxes. Just gluing it into the box structure (epoxy soaked mahog plywood) with no internal liner at all -- the stuff is tough, unlike foam or aerogel, and if it gets beat up it would be easy to replace.

Am I crazy?

Never mind.

[SV Demeter]

Originally Posted by kefroeschner

Has anyone thought of or tried the stuff called "Reflectix?" It is available in hardware stores and is a multi-layered combination of some Al coated plastic film (aluminized mylar?) about 0.5" thick in a flexible roll. It is mostly air space between the layers of al-mylar and is normally used as insulation around engie compartments etc. I do not know the R factor but we used something similar a long time back to keep a nuclear device cool at the bottom of a ery deep and hot hole and it worked well.

I am thinking of trying this as a liner, three layers, in our ice boxes. Just gluing it into the box structure (epoxy soaked mahog plywood) with no internal liner at all -- the stuff is tough, unlike foam or aerogel, and if it gets beat up it would be easy to replace.

Am I crazy?

Never mind.

I used a layer of reflectix in constructing my new fridge. I used it as a radiant as well as vapor barrier. I then added 2 layers of aerogel along the bottom and then 4" of foam all around.

[kefroeschner]

Just read some comments on Sailnet. The consensus there seems to be that it works quite well, but that the optimal configuration is with regular foam of some sort between two layers of Reflectix.

The iceboxes are salon berths and will have about six inches of foam (cushions) on top and about three inches around the sides as well.

[Celestialsailor]

I know its been months but after some technical difficulties with my thermostat, I have completed the refer install. 1.25" of aerogel, a few layers of blue Styrofoam and then back-filled with pour foam. After 2 days of running with bottles of water as a load with the ambient temperature of 98 in the harbor day time and 70 at night the unit did quite well. It runs 4 minutes on and 11 minutes off. The freezer temp is 22F and the box area 37F.

[Saltyhog]

Originally Posted by Celestialsailor

1.25" of aerogel, a few layers of blue Styrofoam and then back-filled with pour foam.

Celestial, So what is the final thickness of the blue foam? It sounds like you used 3 layers of aerogel. Would you use more aerogel / less foam if you were to do it again?