Refrigeration

From time to time I have seen refrigeration units for sale (from reefers) for about $500. Some were diesel powered, some propane. My thoughts here...by using this type of refrigeration I would reduce my need for electricity, and could thus buy fewer collectors, batteries, etc.
Questions: Is it feasible to diy a frdge cabinet. 1. Most commercial units only incorporate insulation. I would like to incorporate some mass as well to retain the cool. 2. Can these be converted to biogas or veggie oil? 3. Am I completely off the wall here?

I -think- all diesel powered refers would be vastly too big for typical homestead use, unless you need a walk in cooler.

Propane units from a truck would also have a compressor, and would also be much too big of capacity for typical refrigerator use. Look up the fuel usage numbers for a typical truck unit--it's a big number.

But there are also absorption type refrigerators that have only an adjustable flame, and no other moving parts. Here's an example of an absorption refrigerator:

https://www.lehmans.com/p-3505-dometic-kerosene-refrigerator.aspx?show=all

RV's often come with the propane fired absorption refrigerators AND an electrically driven compressor so you can run off either fuel. You might be able to get one cheap through a salvage place.

Dometic is pretty much the benchmark against which all others are measured. The amish use them a fair amount.



Most if not all of the absorption refrigerator units use ammonia as the refrigerant. It's way way way more toxic than the "freon" based conventional refrigerants. Leaking ammonia refrigerant can kill you. The domestic sized units have such a small amount, I wouldn't be overly worried about that, but it is a meaningful difference.


How big of a refer do you need???


troy

My grandmothers farmhouse " fridge" was a dumb waiter that raised a set of shelves from the cooler basement to the main floor. Another old time thing in Canada was the cold closet. Built on an outside wall it was insulated from the rest of the house but allowed cold to get in from the outside. Basically a miniature cold cellar. In most parts of Canada that would mean on the north side of the house you would achieve fridge temps 6 or more months of the year. For off grid this is the important time since that is when your solar is weakest. If your electric fridge didn't need to run in the winter a smaller system would be adequate and should have the capacity in the summer to run it.

Look at the cool bot website for diy cooler box design.

Can be done, but I agree that it is definitely too big for the average home needs.

Yes, the diesels can be converted to veg, at least the ones that idle the engine. Evidently some of them shut off the engine now.

Unless I needed a walk-in refrigerator, such as for hanging beef or game for days on end, then I wouldn't consider such a thing. It's not the initial purchase price that would cost me big time, but rather running the thing and keeping it repaired. Running a smaller chest type refrigerator would be far more economical.

While a Sundanzer or Steca cost more to purchase, their energy requirements and repair record is far, far better. It makes up for the purchase price, in my experience. And I could make a simple chest frig by splicing in an external thermostat (which would hang over the lip and be inside the chest) , thus making a frig out of a chest freezer. I've never done that myself but I've talked to a few people who did. So I can't give details on exactly how to cobble the thing together. One of my neighbors bought a small chest freezer from Costco really cheap and turned it into a frig.

I have a chest frig, a Steca. It uses very, very little electricity from my solar electric system. Being on solar, I would never consider using anything but a chest unit. No more uprights for me. I started out with a propane upright refrig, but it cost me way too much to run. It hurt my budget buying the propane.

I don't live where it gets cold enough during the winter to use Mother Nature to keep my food cool. Thus I use a frig.

What I have in mind is to find a discarded fridge at the dump that is in good physical condition. Put it on the north wall of the house with a 2 or 3 inch duct at the top of the back running outside and the same on the bottom of the back. Ideally it should have a damper control that is thermostatically controlled but I will probably try manual first. A full fridge with no freezer would be best but for the experiment I will try a normal combination if it is all I can get. Open or close the damper to maintain proper temp inside the fridge. If it proves viable a working fridge could be adapted with a temperature differential set between the mechanical and environmental systems. In the event of an abnormally warm day outside the mechanical can pick up the load. This system should be adaptable to all types of refrigeration.

Thanks as always for well thought out answers. I know that rule one is to minimize the need for refrigeration and that is also what I am looking into ~ it seems to be a recursive process. I like to cook a variety of foods so often have a significant amount of my fridge devoted to open bottles of sauces. my best guess would be about 15 cubic feet for the fridge part. My initial idea about these refrigeration units was "reuse" but it seems that is not practical. The next thought ~ if the unit is built into the house would excess insulation and earth mass provide any benefit?