Building a fridge from scratch

[WHEELEYBIN]

OZEFRIDGE Designed and Engineered in Australia and selling all over the world .

[Uncle Bob]

Another Ozefridge fan here, well designed and they just work.
Also the backup from Louie and co is superb.

[rgleason]

This is off topic, but Peter (and Louie, way later) provided great support to us. I think we purchased in 2005 from Ozifridge, Aus and its been running beautifully. I always found Peter to be open to new ideas and very thoughtful and knowledgeable about these systems. He was patient with my questions until I understood the system.

[Texas Skipper]

Originally Posted by hd002e

I am looking to build a fridge into one of the galley cabinets on a boat that has only had a mobile selfcontained dometic fridge before. I want to put the compressor unit about 5-6 feet away into the lazarette to keep the hot air away from the cabin in the summer. I have about 130L of space in the cabinet but after accounting for insulation I expect for the inner volume of my fridge to be about 65L. I am planning to have a stainless box made and then glue layers of insulation foam between the stainless box and the interior walls of my wooden galley cabinets. The access will be from the top.

Other considerations are for a drain hole in the bottom for easy cleaning. Hole for wiring a door open sensor and LED light. Tray supports so I can have a shelf.

I have spoken to some technical people at industrial fridge manufacturers here in Turkey but my engineer’s mind is still craving more information especially around best practices and design considerations. Are there any resources you guys would recommend me to read up?

I would also love to hear from anyone who has gone through building such a thing themselves and what you yave learned, what would you differently?

Thank you!

That Sir is quite the project I must say. I have installed a permanent refrigerator in the boats original ice box but I started with the right size “dorm fridge”. I started out by measuring the interior of the box. Mine turned out to be 3.6 cubic feet. My ice box had a large cabinet beside it that had enough room for me to install the compressor and condenser coil inside. I went to Home Depot and found a 4.0 cubic dorm fridge. I think I spent $312.00 for it.
I took it back to my boat and started tearing it apart. This was what I thought would be the hardest part but not so. Everything was plastic and I was able to just basically peel the skin away. Inside I found out that the condenser coil was wrapped around the walls of the case and made of very soft aluminum. The hardest part of the entire job was handling the aluminum coil without crimping it. Of course it was attached to the compressor and the evaporator ( the evaporator was actually the freezer box of the dorm fridge). There was plenty of tubing and wire on the freezer box to mount it anywhere within the boats ice box. I decided on the back wall of the ice box. I then cut a hole large enough to pass the dorm fridge freezer box through the cabinet and into the ice box. I mounted it to the back wall. The piece I cut from the boats ice box came out in one big fiberglass and foam slug which fit right back in place after making a little room for the wire and aluminum tubing.
The back of the neighboring cabinet was the inside of the hull. I had about a 4’ x 4’ area that I could spread out the aluminum tubing of the condenser. I gently routed the coil back and forth along and against the inside of the hull. I also twisted aluminum foil around it to act as additional heat sinc. I mounted the compressor to the floor of the cabinet and ran the wiring to a new 120v circuit breaker and “BINGO” dockside refrigeration. Somewhere around $500.00.
Of course I had intended to reclassify that ice box plug back in but the silver tape just never wore out. I installed a few 12 volt LEDs and a switch on the lid.
I also installed a small chimney with a small fan to move the air around the box.
I lived aboard my boat for over a decade. The fridge was still running great after seven years of use. Sold the boat last year and determined that the fridge was a positive use of time and money.
I would have to defrost about twice a year. I just brought a water hose in, used it to wash out ice. I always got the controls wet no matter how much I tried not to but it never seemed to hurt anything.
Good luck

[GreenHeaven]

Originally Posted by Bowdrie

For built-in boxes, stainless steel has largely gone the way of the Dodo bird.
In all of the retrofits I've done, (installing refrigeration in an existing stainless box,) very few times have I come across one in which the insulation was hermetically sealed against the metal.
In general, metal boxes are excellent producers of condensation, and repairs, (like patching an un-needed hole or a leaking seam,) are almost futile.
Simply trying to glue insulation against the metal without any air space(s) is a "hope-and-a-prayer" situation.
If the box can be turned upside down, a dam built around it, and liquid foam poured all over and around the box then a reasonable chance of success can be achieved.
The liquid must be poured directly on the metal and allowed to expand outward, you cannot just pour the foam in such a way as to allow the foam to expand against the metal.
Also, expect that if you drop a frozen "something" of much weight into the box the metal could flex and compromise the insulation bond in that spot, (foam doesn't like to flex).
A process that was used in the old days was to "glue" the foam panels to the stainless with tar, applied hot, and the foam panel(s) stuck on to the tar before it hardened.
Really, a well laid-up/thick fiberglass box is superior for a DIY project.
The need for zero air space between box and insulation still applies.

Could someone please help me understand this.
If I have several layers of interlocked 1inch sheet insulation material up to 4 or 6 inches think, how is a small airgap bnetween the SS box and the first layer of foam a problem?

[Buzzman]

The issue is dewpoint. If there is any airgap at all it is easier for water vapour to reach a lower dewpoint and so condense out onto the steel surface which eventually leads to rust.
Having the insulation 'bonded' to the steel helps prevent this, and moves the air/solid surface to the outside of the insulation, and raises the temperature at that surface, so dewpoint is not reached as easily, and so condensation does not occur as readily.
Dewpoint is the point at which water vapour changes state from vapour to solid/liquid water. The actual temperature at which this occurs depends on the air temperature at the interface.
So if the air temp is reduced the dewpoint is reached faster, hence why insulating a box raises the temperature and so raises the point at which the dewpoint occurs, because warmer air holds more water vapour than colder air.
So warming the boat, or the surface, prevents water vapour condensing.
But if there is an airgap, then the dewpoint is the surface of the steel, not the outer surface of the insulating material.
Hence why the bond is mission critical, and why not having steel at all is better.

[Martkimwat]

On my small 26 foot Parker 27 liftkeeler, the existing passive coolbox did not have enough room around it for more than about 35mm (1.4 inches) of insulation so I cut/sanded off the existing spray on foam and replaced it with 25mm (1"inch) VP panels. It is a 65 litre box and now typically draws around 24 amps/pd and easily gets down to +2ºC although it cycles between +2ºc and +5ºc. It does that when empty and obviously runs even more efficiently when full. I have had it running at below freezing but it draws around 38 Amps/pd when operating at that temperature, and since a freezer needs to operate at around -15ºC or lower to be efficient I never bother to use it as a freezer. I tried making a small air dam out of 1" closed cell foam to hold some frozen items but it was not successful as my cooling plates are near the top of the box along two sides (L shaped) with a small shelf just below the plate.I might try the idea of blocking off the entire plate with a small fan to distribute cool air to the rest of the coolbox but then again, I would then have issues of where to run the power supply, now that the box is complete and built in ( I had to completely remove and rebuild the galley worktop area to access the coolbox)

[rgleason]

What are 25mm (1"inch) VP panels?

[Martkimwat]

Originally Posted by rgleason

What are 25mm (1"inch) VP panels?

Vacuum Panels as mentioned by several others earlier in this topic. I have a supplier here in UK that I have used before. They usually make VP Panelled boxes for shipping medical supplies/ Human organs that need to be kept chilled whilst in transit. My panels for my 65 litre box cost about £400 with shipping costs included. The VP panels comprise a Mylar package with some form of black carbon like material inside that is then vacuum evacuated and sealed ( I managed to puncture one by accident so I now know what's inside) It's messy stuff to clear up if you do inadvertently puncture one. With only 35mm to spare, I encapsulated my panels in a 5mm layer of foam normally used to insulate laminate flooring. I did it on both sides to protect the panels. I then covered the whole thing in Mylar 'space blanket' material and taped it altogether using 100mm aluminium foil tape. I don't know if it helps but it seemed like a good idea at the time and it was inexpensive.

My coolbox is an odd shape as it is shaped to fit the hull so I had to step the panels whilst maintaining 90º angles to get the edges as close together as possible. The two side panels (fore and aft) were OK to be angled as they butted up to the other panels at 90º. I filled in the spaces with closed cell foam (plenty of room at the bottom and up the outer side) to make it easier to create a shape that could be taped up tight before applying the Mylar space blanket and foil tape.

[stainless guy]

I used to build stainless steel fridges when I was young

Commercial grade for restraints and such so there was an air circulating coil in each one which takes up alot of space.

The one that I would do in this instance would be to wrap the outside with copper tubing and a good coat of thermal mastic then a layer of spray foam

The only other thing you need to do is make sure you have a break from the liner with some sort of poor thermal conductor such as plastic or you will have heavy condensation around the door gasket

you can order magnetic fridge door gaskets in custom sizes