Building or modifying an insulated ice box.
Efficient performance from a refrigeration system depends primarily
on a good design for the box with sufficient insulation and an air
tight construction.
Many boat builders today are constructing excellent boxes but there
are many situations where improvements or modification of the box
will dramatically improve the performance. Adding insulation to the
bottom or sides of a box will often help improve the insulation value,
reduce the volume and improve the shape of an existing box.
Building a new box from scratch is a big project but it can be done
with very good results.
Here are a few general suggestions.
Insulation
How much is enough? Is more always better? The answer to these questions
like so many questions is "it depends". Insulation works
on a diminishing return. The first inch gives the most benefit and
each additional inch provides less benefit.
Heat gets into the cabinet not only through the insulation but also
through opening the door or putting warm things into the refrigerator,
less than perfect seals, the door frame, etc. The shape of the box
is a huge factor since it is the surface area not simply the volume
that is important.
In general, the rule of thumb goes like this:
For a refrigerator box:
4 cu ft or less, use a minimum of 2 inches.
6 cu ft will need 3 inches
bigger than 8 cu ft needs 4 inches
For a freezer:
2 cu ft or less, 4 inches minimum.
4 cu ft or less, 5 inches.
larger than 4 cu ft, 6 inches.
To summarize
Keep the box small and an efficient shape (square is the ideal).
A front loading box is not a problem as long as the door seals are
tight.
If you have a separate freezer be sure to have it well insulated and
no larger than necessary - empty space in a freezer will still use
power.
What kind of insulation? We recommend extruded polystyrene - such
as Dow Blueboard or Owens Insulpink. It is conservatively rated at
R-5 per inch and will not absorb moisture so it will maintain its
insulation value. Other foams may have higher initial insulation values
but may quickly degrade in the wet marine environment. Vacuum panels
can achieve much higher insulation values but they are very expensive,
fragile and difficult to handle.
Extruded Polystyrene insulation is usually available in sheets of
several thicknesses up to 2". It is easy to work with and it
can be cut on a table saw. It is easy to obtain at a local builders
supply and is not expensive.
A new interior liner can be made with Strutoglas flexible fiberglass
panels - made by Kemlite this is sold by Home Depot. The product was
originally sold as a wall panel for walk in freezers. It is usually
sold as a bathroom wall panel.
http://www.kemlite.com//structoglas/seq_structo_index.cfm
West system ( or other similar Epoxy adhesives ) can be mixed with
a filler to make a adhesive paste to bond the insulation panels and
the Strutoglas panels together. When the Strutoglas is bonded to the
polystyrene foam it will produce a very rigid and strong composite
panel.
The panels can be bonded to one another by masking the edges of the
joints and forming a fillet of epoxy and filler.
An air tight door or lid is as important as good insulation.
Gaskets should be checked and replaced if they are worn. Clean Seal
manufactures a number of very high quality gaskets. We normally have
several profiles in stock .
www.cleanseal.com
Another option may be a Pre manufactured lid. These are available
in 3 sizes and include vacuum panel insulation, lid and frame. These
can also be mounted vertically for a front loading door.
500-0100 $269.25 Small Hatch - 10.5" x 8" opening
500-0200 $284.40 Medium Hatch - 13" x 10" opening
500-0300 $293.65 Large Hatch - 18" x 13" opening
Contact us for more information and full dimensions.
