Three things are on my mind regarding fridge/freezers:
1. Can I get more value by reducing the cold losses and learning
to be smarter about what needs to be stored in the cold?
I'm looking at an older vessel that has 12V cooling
. It draws more amperage but is in very good condition. I'm actively researching replacing the insulation
with some top shelf stuff, hoping to keep the heat transfer minimal.
Heat transfer works both ways, though. Adding lots of hot items will raise the internal temperatures as much as an insulation leak. In the past I had a deep fridge and kept several gallon containers of water
stored in the bottom. The water acted as a cold source and if the added mass was small compared to what was already in the fridge, the temperature rise was slower than filling the fridge with warm objects.
From my research
I've learned that a lot of items don't need to be kept refrigerated, and that many others last far longer by being kept chilled. And while there's no denying that a cold beverage can be a fine reward for hard work, I wonder if a cool one isn't as good. So, I'm working on a list of priority items that I consider necessary for cold storage
Better insulation leads me to not want a front loading fridge since the cold loss is far more than a top loading unit. While it can be quite convenient to open a door and look in, again I'm not sure I want to pay the energy cost. I'm learning
that by carefully loading and arranging the contents of the fridge, I can get to most everything with little effort.
By keeping the fridge lightly loaded, the cold air is allowed to circulate better, reducing cold and hot spots and allowing the system to be more efficient.
2. Can I live with a smaller box and do I need a freezer?
I'm under the impression (and possibly wrong) that a freezer is the biggest draw of cold power despite the thicker insulation. I've learned from hard experience that loading the freezer can lead to expensive problems when it fails. Ice and ice cream are a real luxury and I'm not sure I want to pay the price
It seems to me that the higher the temperature difference, the greater the flow of temperature. A freezer at 5F and the ambient temp of 90F has a higher temperature difference than a fridge temp of 40F and the same 90F ambient. In this case, the freezer difference is about twice the fridge and since I don't have twice the insulation, there is the chance of more cold loss.
I do want to keep items that don't seem to have a long shelf life in the freezer. Those tend to include meats, veggies, and caught fish
. These items seem to taste better than their canned competition. By having a freezer I can keep the food
costs more in line with my budget
and have treats when the fresh produce is long gone (I have a slow boat).
3. Can I keep the energy costs reasonable?
Insulation, smarter positioning, and understanding what is best to be kept cold seem cheaper than a bigger compressor
, more batteries, or more power generation. Having used engine
driven compressors, and very much liking how fast these pulled the cold plates down, I'm still heading for a 12V system. I can leave it alone and go away for a day or two and not worry about these valuable items thawing or spoiling.
I'm also wondering if adding a bigger cold plate would allow the system to keep contents cool before having to start. The downside, I think, is that the compressor
will have to run longer in order to bring the larger plate down to temperature.
One thing I did learn was to have the fridge/freezer running when I added new, and sometimes warmer, items to the units. This way, the system has a good chance of getting the contents cold, suck out as much heat as possible, and slow down the cooling
time. Where I normally ran the engine
for an hour/day twice a day to keep the system cold, I'd run the engine for a couple hours or a couple of cycles when adding lots of warmer items to the system.
As interesting the idea of using the fresh water tankage as cooling for the chiller system is, I'm very leery of this due to the potential of catastrophic water loss or contamination. I wonder if I might prolong the heat exchanger
by scheduled flushing
of the system with fresh water and a salt
I'm thinking that for the cost of a bigger/newer/more efficient cooling system I'd get a better ROI by improving the insulation, making sure the compressor system was running as efficiently as possible, keeping the items stored in the cooling system to the necessary items, and accessing the system as little as possible. I'm also becoming a convert to canning. This simple, inexpensive, and well proven technique for preserving food
items requires little energy (usually propane) and keep for long periods of time with no energy preservation requirements.
From my research
, the fridge/freezer system is in the top 3 energy draw systems. Perhaps it's time to look at either modifying my cold requirements, actively preserve fresh items for long periods with low energy requirements, or use this expensive, but not necessary, system in a better way.