I will throw in my 2 cents on refridgeration.
First that fourmileisland ice box sounds great. I am sure it works well for him. You first must have a climate that will freeze a large enough mass to get you through the summer, fall until it can all freeze again, the size of the unit is monstorus, not likely something backward compatable into existing homes, you would I think need to build for it. The weight alone of just the frozen water is 1550 pounds, something like 186 gallons of water, cost back in 1981 for materials was somewhere around 1000.00 It would be a great deal more now (how much?? guessing 2500-3000). It used r134a I dont know if thats still available. I have been tempted to go this way but, improvements in fridge construction are really coming along.
Right now at Home depot there is a fridge 17 or 18 cuft that is claimed to use 300kwh/y.
That is only .8kh/day. That is good for a full size fridge (with freezer up top) Now this fridge is like all now days frost free, and I would guess has door gasket heaters as well (I have found most do, yea its crazy heaters on a fridge) If you buy a aftermarket temperature controler you can plug your fridge into this controler, then the controler to the wall, run the temperature sense bulb into the fridge part, tape or glue it to the side wall, and now set the temp you want on the controler.
What you are now doing is controling power to the fridge, in effect pluging it in when needed, and unpluging it when not. What this should do is defeat the timer ccts that are built in to turn on door seal heaters and defrosting heaters. You will now have a fridge that is not frost free, you will need to defrost it manually now, and again, but I am guessing that on average that should drop its daily operating cost down to about .6 maybe .65kwh/d.
That is very good and if you are happy stop there, But you can go further.
Now for a little better performance ( I am only guessing/have not tested this) plug the temperature controller into a 24 hour timer, set the timer to turn off at 10pm, and on at 8 or so. allways keep the freezer full(even jugs of water) and it should coast through the night. Yes when it powers up The compressor will run longer than normal to bring the unit back down to your set point, but I suspect its operation is more efficient if running longer than it is cycling on, and off a bunch of times (If anyone knows different please correct my theory). Now we could be down to .52, .55 kwh/d
That is good and if happy, stop there, but if you wish to go further then do what I have done.
My fridge is older, 4 or 5 years old. It used something like 400 kwhs a year. This model has a large freezer on top 5.5 cuft or so. I used the same temperature controler I suggested, but I put the sense bulb into the freezer compartment. I plugged up the holes that the cold air blew down through to get into the fridge. So I now had a 5.5 cuft fridge at head height that uses .266kwh/day (200 watts of solar , and 2 hours of sunlight would run it)
That is very good. I know people think thats small, but it is not so, I just never had to think when I used the whole fridge. I still can use the space below for storage. This all requires no permanent changes to the fridge, and very little work to do. I like little work.
Now I am still thinking of how to improve this, and have some ideas to try ....but my to do list is long right now..maybe by next winter I will see if I can do more.
I should add that in doing this mod it turns out the freezer part that I now use as a fridge is frost free...doesnt make sense but I have never needed to defrost it as I expected I would?
I agree - it won't retrofit into a 32" space in a row of cabinets but I think it can be put into other (perhaps less convenient) spaces. I have a mudroom off the kitchen that will work nicely, I think. But I'm not sure the weight is an issue - don't conventional refrigerators have almost the same mass/square foot? Certainly, I would think a piano would... As for the cost, I didn't look closely enough at the website, I guess. I can't imagine how it would cost $1,000 even in today's money. Reclaimed lumber, reclaimed insulation, some old racks, some copper pipe - the only thing that seems to me to be likely to be expensive is the "refrigerant". Since i don't want to use anything Freon based (and since I haven't a clue what else one might use) it's hard to estimate a cost but it seems to me that it must be possible to do it cheaper than that.
We have a 22ft/bottom freezer, rated at 425KwHr/year but since we have all that free cold outside, I'd love to park that unit from October to July, especially since the winter months are when I get the least power from my PV.
I'm not sure what you mean by an "aftermarket temperature controller". Can you post a name or link that I can see what you're talking about?
Anyway, it's an interesting discussion and I thank you for your ideas. I'd love to be able to reduce my power consumption during the winter.
PS - and the silly attempt to force a normal font size may be unnecessary but everything looks really wrong on my screen right now!
posted 7 years ago
The cost is from his own notes, for the type of insulation he wanted he "foamed " his own at a cost of 450.00. The galvanized metal liner he had fabricated to his specs at a metal shop. The plastic liner, type, construction, and the way it was seamed he had fabricated, again to his own specs. Custom work does not come cheap. He must have done it right as it has worked this long, could he have done it cheaper, maybe, would it have lasted?
His name is Bob English you can email him through that web site for further info, and detail. That web page simplified its construction, as with many things the devil is in the details. As someone who loves things cheap, I have come to learn that it can be a false economy, I have come to believe that if it is good enough to do, then it is often good enough to over due.
That weight is very significant, the water, then the other materials are going to be nearing one ton, you better place that over a load bearing wall. He did, the center of mass is over a outside wall.
Just to give you a idea on what custom metal fabrication costs consider this, you are walking into a metal shop with your specs for a one off. I would estimate that just to build that inner galvanized box would require at least two full 4x8 sheets of galvanized steel, considering the weight surounding it, I would not go less than 14 gauge(12 would be better) so 2 sheets at 70 a sheet, so 140.00 in material for just the metal box. Now this is not that complicated of a box, but due to what it must keep out, I would have to suggest folding the edges and soldering the seams for a proper job. To estimate labour it would be reasonable for a shop to assume one day at a shop rate thats appropriate for your area (say 85.oo per hour). So 8X85= 650.00+140 gives you a cost of 790.00 for your custom fabricated box (I think A good sheet metal man could knock that box of in 4hrs). You get the idea, costs climb fast, nothing is as cheap or as easy as it first looks to be.
The type of controler I suggested can be found for sale at amazon.com for 47.00, plug, and play no wiring skills needed. Search under the heading "refridgerator or freezer thermostat"
PS: I just seen where you mentioned saving power in winter from your PV. If you set up a fridge like mine (roughly a 600.00 fridge), then add a 50.00 dollar controler, and can live with a 5.5 or so cuft fridge (bet you can with a little thought), you should be around what i am at .266kwh/day, now if you wish to go even better, keep a couple 8 liter jugs of water frozen outside in the winter. From my tests a couple years back by placing one frozen 8.5 liter jug in my modified fridge, my use dropped to .500 kwh in 72 hrs, in other words by rotating out a 8.5 liter jug of frozen water every 3 days my fridge used just 166 watts a day or if we go by a hour average thats just 6.94 watts per hour. Sure my fridge became maybe 4.5 foot fridge then due to the volume taken by the frozen water, but I still had lots of room. Anyway, you can see why I didnt consider building that monster fridge- to much work, to heavy, took up too much room, and to expensive, for me anyway.
Now the fridge he would have been replacing would have been from the 70s, it may have used 2, maybe 2.5 kwhs a day, and building that fridge was one smart move, made sense in every way, but now?
I cant see how it could be when I am only using a couple hundred watthrs a day. I may only have 5.5 cuft, but his was only a little more at 9cuft.
posted 7 years ago
A write up of that fridge for those looking for more detail can be found in the summer edition (1981) of "Rodales new shelter" There must be a scaned copy somewhere out on the net.
I looked into this topic several years ago. I considered primarily air conditioning in the off grid setting. However, much of what I examined applies to food refrigeration as well. First, in most cases it makes sense to stick with a conventional commercially available vapor compression unit (i.e. the refrigerator and freezer we're all familiar with). Modern units are highly efficient. If the concern is to minimize the consumption of fossil fuels, then you could size your PV system accordingly and consider a battery charging back up generator powered by a small wood gasifier or biogas system. For the mechanically inclined, I believe it is not unreasonable to build an ammonia absorption system heated by a small biomass furnace. However, this would make sense only for a fairly large system designed for either air conditioning or perhaps a very large freezer (or both as the liquid ammonia generated by a central system can be used in both applications). Personally, I'm convinced there is a lot of potential in building such a system. However, it's not for the novice to attempt. There have been discussions on this thread about the corrosive nature of ammonia. While this is true my research suggest that steel handles ammonia quite well. Plus, using stainless steel evaporator coils and placing fittings outside a living space seems extremely safe to me. It's unfortunate that the ammonia absorption refrigeration system is not well understood by most because it is extremely simple. Think of it as a distillation apparatus. You heat an aqueous ammonia solution to separate the ammonia not unlike an alcohol still heats beer to separate the ethanol. However, in this case it's under pressure. You send the liquid distillate (i.e. ammonia) through a restrictor to the evaporator coil to make things cold. After the ammonia vaporizes it is recombined with the water from which is was separated earlier. Pretty darn simple, huh? The simplest system uses a small pump to send the aqueous ammonia solution to the heater, and this pump requires about 5% the mechanical energy of a vapor compression system of the same cooling capacity.
@roger if you're still following this thread... I live in a cold place too, and this summer I hope to make an icehouse while i have a machine around to dig the root cellar. I'll pack it with largish blocks and possibly freeze them together in place if it would help..
Regarding your ice room in the mud room, not wanting to carry the ice in but wanting to freeze water in-situ... Maybe I'm overlooking something but it seems like using a refrigerant or heat exchanger is really over-engineering this problem. The ice is going to be blocked off in a super insulated container or room, correct? Why not build it next to an exterior wall, and build a super insulated door or hatch through the exterior wall? Open hatch in the winter, the ice room becomes ambient temperature, water freezes, the insulated ice box will serve in reverse to keep the mud room insulated from the outside cold. In spring close the external hatch on your ice and access through the ice-room entrance in the mud room.
Just a thought..
.. as others have mentioned, it is a lot of weight, check the structure...