Building a fridge from scratch

[martin.purser]

I think every one has covered the bases. I built 2 units a few years ago, both plug and plays using fiberglass box liner. Two things extra I did. 1. Used refrigeration caulking on my joints to stop cold seeps. The 2nd retroactively was to install a minicomputer fan to circulate the air. I found with them being "chest " fridge and freezers. that anything in the fridge at the bottom was hard frozen whilst at the top not so. This was a problem in the fridge not so much the freezer.

[Disailor]

My $.02: With an internal temp of 36F water is liquid & finds its way to the bottom. As it drains it pulls warm air in resulting in more condensation. My cure was to put an "S" trap in the flexible drain tube. Problem solved. Sitting the drain on a sponge increases the evaluation area so bilge water is minimal.

[Mexican Hat]

For sharp, square edges on a foam insulated lid you could use a laminate, the sort of thing used for cheaper kitchen counters. Its easy to glue on and can be trimmed to the foam edge with a router quickly and easily. I made lightweight cabinets that way years ago. On a fridge I'd probably run a thin bead of silicone or something along the joints.

[j.g.evans]

I converted the ice box on my C&C36 to a refrigerator and freezer using a kit from rparts.com. It came with a Danfoss DB50 compressor, drier, sight gauge, cold plate and many other parts that don't seem to be included with commercial, 12V, boxes. I custom mounted the components behind my stove in idle space. I mention this because you don't need a kit and can build your own arrangement. I just checked and found rparts.com is still in business. They offer parts and A LOT OF DOCUMENTATION. They mention a manual for a kit.

My unit is both fan and water cooled. If I were doing it again I would remove the convection condenser from the back of an old refrigerator and then the "kit" would be free of fan noise. Water cooling is of marginal value.

[rgleason]

Originally Posted by j.g.evans

Water cooling is of marginal value.

I don't agree with this. I supercharge the refrig when the engine is on and power is available, going in and out of harbor.

With the engine on, the Ozifridge has a mode to turn off controls and put the compressor on high using 7 amps or so, Then I turn on the water pump that pumps from the domestic tank and helps cool the refrig faster. It is all while powered from the alternator, not batteries. It is a very useful mode and saves on the need for big batteries.


Agreed about insulation. There is AEROGEL https://www.mcmaster.com/silica-aerogel/
expensive, but will result in a very low energy refrig.


https://conceptgroupllc.com/high-tem...l-alternative/

[MJH]

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!

I biggest problem with boat refrigeration is the poor quality of the insulation material chosen. Therefore, I would research which gives the highest R value and use that material. I understand that there is now one new material that is head and shoulders above the rest per one inch value. Secondly, I would place it as far as possible from heat generating sources, i.e. the diesel engine. Its remarkable how many refrigerators are next to or between the diesel and galley oven.

Good Luck.

[sinnerman]

A friend who sails the world in his large catamaran used vacuum insulation panels to insulate his fridges. He swears by it.

Here is the site of one example:
https://www.recticelinsulation.com/e...ulation-panels

cheers

[rgleason]

https://www.cabotcorp.com/solutions/...mpression-pack


file:///C:/Users/fcgle/Downloads/Brochure-thermal-wrap-blanket.pdf


https://www.mcmaster.com/silica-aero.../r-value~2-46/


5/8" thick 60"x 58" R=2.46 for $492 so to get R=24.6 it is 10x's that cost. Very very expensive!

[Colin Stone]

I used Frigoboat components in 2010 to build a 90 litre chest freezer under the galley floor. Internal dimensions 40 x 50 x 45 cm, add 109mm on each face for approx outer box size. Danfoss BD50F compressor with keel condenser - so no heat in hull. Plate evaporator on 2 sides of box - even bending the corner in the plate evap was simple. All Frigoboat components are precharged, so very easy to assemble.
Actual cool box is 2 x 50mm celotex foam bottom, sides and lid, 100mm inside a 9mm "betonplex" box. I could probably reduce the lid thickness to 50mm and gain a few litres volume. Outside of complete box wrapped with thin silver bubble wrap type insulation. Lining is 1mm white polystyrene sheet, sourced from model supplies, . Stuck into place and joints sealed with white sealant/adhesive.but pretty much the same as domestic fridges.
Runs at - 12C. Didn't include a drain and no moisture in bottom after 6 months running.
I added a larger filter dryer in 2020.

[Jon Hacking]

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!

I've built fridges into 2 boats, now, but I don't like the thermal properties of SS. I much prefer epoxy/fiberglass, as I can do all that myself, & it's not a thermal disaster area like SS is. I:

• Epoxy sealed the wood where the fridge will go.
• Taped the corners with epoxy glass, so the area's pretty waterproof.
• Cut sections of rigid foam insulation & "glued" them in with canned squirt-foam
• I used 2 layers of 2" thick insulation, & 8" at the bottom, but that uses a lot of volume
• Mounted a sheet of thin plywood with bolts sticking out for my evaporator-box. My evaporator was wrapped into a box, & I mounted it vertically, put 1/8" of foam around it, & a Starboard (HDPE) bottom, so what was inside the evaporator would freeze, but the fridge-box wouldn't.
• Squirted a bit of foam in the corners, then rounded them off with a spray-can onto which I'd taped some coarse sandpaper
• Cut the counter-top out with a jig-saw set to a slight angle. I used this removed piece as my door, so the Formica top would match the counter.
• Cut my door in half, sealed the wood with epoxy, & rejoined them with a SS piano hinge, so either half could be opened independently.
• Routed out the Formica top, sealed the wood, & flush-mounted 2-finger lifts (handles)
• Stuck 4" foam to the underside of the door, shaped with taper on edges
• Foamed the box where the door will go, loosely shaped to match door-foam
• Glassed in all foam with 2 layers of thick epoxy-glass
• Painted the interior white
• Mounted my evaporator-box, just under the door
• Drilled a hole through the insulation at a bottom edge, ran my evaporator pipe through it, epoxy sealed it, & mounted a vinyl hose there for a drain. Carved a cork to act as a stopper.
• Taped wax-paper (release) to the area around the door, shot the door & its glassed-in insulation with a layer of silicone (to become the seal), sat the door where it was supposed to go, sat some weight on top, & waited 2 days for the silicone to cure, making a custom-fit seal
• I put 4 small screws through my glass to hold up a single plastic-coated wire shelf
• I found my evaporator pipes tended to sweat on their way to the compressor, so I encapsulated them in squirt-foam, to keep the condensate from puddling there.
• Drilled a small hole through the insulation for the thermostat.

Hope this helps give you some ideas.

[Andrew Lippman]

I replaced engine driven and 110v holding plate fridges with Seafrost units. They use danforth compressors and are made to do it yourself. Cleve at seafrost can make a custom evaporator. I visited his shop and saw what he does there — very clean work.

I have both water and air cooling. A switch turns on the water pump. Not clear which is more efficient — depends on water temp since you have to factor in pump energy.

Highly recommended.

[Franklyn]

Here's a few pics and designs, inclusive of final design for a Pearson 35 reefer. You can see the original ice box is 2" foam sandwiched between 2 fiberglass facias.

Here's what matters:
1. If power drain rates are not an issue, 1.5" minimum foam all around is necessary to provide enough insulation so the compressor is able to routinely cycle, and not freeze up. It must also be this deep to prevent cabin surface "Sweating" (bigger issue of mold than electricity use). Beyond that, you are trading off cabin space and container volume for increasing thermal efficiencies; not your primary concern.

2. Your first design issue is how big an evaporator plate? The answer is: AS BIG AS YOU CAN GET in that space; wrapping around the entire perimeter is perfect. The compressor does not care how big a plate across a wide range of sizes, so you can't go wrong there. The plate must be mounted as a standoff to allow air circulation.

3. You must put in a fan system. It should turn off when you open the hatch, but on when the door is closed.

4. A light can tie to a contactor switch along with the fan. Light on when door opens.

5. An air-cooled compressor is about $200. The Same unit with air and water cooling is about $1200. Buy the second unit. All the talk of efficiences is irrelavant compared to water cooled vs. air cooled. In any tropics, water cooled compressors are massively more efficient.

6. Someone went "go with a magnetic latch". That doesn't work on a boat that can shift vertical 50 degrees. You have to have mechanical latches that lock on boats. Remember that a "pole topping" is a boat flipped end over end...survivable if no head injuries from flying beer cans.

7. Thermostat: Place in the airflow NOT directly on wall of box

8. Drain is necessary. You WILL spill. You MUST clean. You clean out, wipe out, hose down and drain and pump out. Any other way is nothing but tears.

HINT: If you install a drain line down to the deep bilge, your upper bilges won't get dirty or food debris particles...everywhere...they are 'confined' to the deep bilge....

Links to the pics below.

https://www.facebook.com/media/set/?...9128533&type=3

[wholybee]

Originally Posted by Franklyn

Links to the pics below.

https://www.facebook.com/media/set/?...9128533&type=3

Broken Link

[Buzzman]

One way to get 'neat' edges without vacuum forming is to use polytheylene plastic sheeting and clamping.
So make your male mould, with neat 90deg corners, then brush epoxy on, add suitable glass (perhaps only 6oz), then cover with carefully pre-measured and cut pieces of 30-50 micron plastic film, then clamp wood or whatever over this as required.
You might need to make a 'rectangle' of 1" x 1" that slips over the mould and enables a close and tight clamping.
Epoxy doesn't stick to the plastic sheeting, so when epoxy hardens prise the timber off and the plastic sheet *should* enable this to come off easily.
I've done this for right-angle corners before.
Requires very careful set up and accurate measurements, but clamping force is not high, as the epoxy glue is what holds it all together. So firm rather than super-tight.
As others have suggested it's also a good idea to *carefully* cut the lid for the box (i.e. the benchtop part of it) out of a sheet of material that will become the actual benchtop. So something laminated or melamine coated for example is a good choice.
As others have suggested, using straight laminate, which comes in sheets, approx 1.5mm thick, cut in strips and epoxy glued to the various 'step' surfaces *can* work, but will always be a sharp corner/edge and liable to catch and over time split along any outer edge seam.
I used to make kitchen tables and laboratory benchtops this way 40 years ago, and some of them are still going, so it depends on the quality of the work you can perform.
But if you want to cut sheet laminate you MUST use a small 'laminate router', often called a 'laminate trimmer'. Run it against a straight edge for dead accurate straight lines, or using a ball-bearing trimming bit, along the edges to smooth them.
A file or sander is used to take off the arris on the edge, but no more than that.

[Robjl]

You won't do any better than "Ozefridge.com"
I have built my own several times, can't better the Ozefridge results even with a salt water condensor.