efficiency,
Ah yes! There's always a tradeoff. As with CF bulbs, the equation has a lot more inputs than it would seem at first glance. Performance issues never seem to get noted in all those efficiency charts. I owned a very similar refrigerator in a previous home. Any absence of more than three days froze the milk. That quickly turns into a "quality of life" issue that it's impossible to put a dollar sign on. This churlish old Westinghouse maintains a remarkably steady internal temperature that keeps soda and beer really crisply cold but always unfrozen. I know that from when I monitored it and empirically by how cold canned soda is when I drink it. (-: I'm coming to appreciate this old Refrigersaurus so much I think I will give it a name and go pat it on the head.
Constantly running fans = constant maintenance. I'd say PC maintenance issues just about doubled in our company when PC CPUs began demanding high RPM/CFM cooling fans. I have a remarkable 900MHz Gateway that uses a shroud over the CPU to allow the power supply fan to cool it without needing a separate CPU fan. It's just about maintenance-free.
I just saw an interesting Netflix DVD: "Who Killed the Electric Car." It shows pretty clearly how poorly companies react when faced with government efficiency mandates. They'll comply, but they don't like it. As a consequence, I believe the newer equipment made under mandate is far more prone to failure than older gear. I have an old, pilot light gas water heater. I could replace it with a piezo unit but I don't because when the power fails, I still have hot water. You can survive a long time in the cold and dark with hot water! We've gone for nearly a week that way in the winter, but we're both from up north so we don't mind the cold. It was sort of like camping in the backyard. Sure, it costs more, but it appears to cos t lots less than generator would, and that's what it would take to make the new one work through a power failure the way the old one does.
The point is newer is better in some ways, worse in others. In the old days you could fast forward through movie trailers on rented tapes, now those are "user prohibited operations." Newer ain't always better. I prize reliability and this Westinghouse has delivered that in spades. Is it less efficient than I would like? Sure. Enough to make me junk it? Hell no.
Those are *exactly* the types of costs that aren't factored into the egghead studies of pure energy efficiency and kWh costs. I don't know about you, but a refrigerator failure that involves waiting for a serviceman and perhaps a second follow-up service call can *easily* cost us as much as the box itself if it fails on the wrong day. I hate it.
If keeping a 30 year old box whose curriculum vitae is well known costs me in kWh$, then it's something I am willing to pay for. I know this sorry-looking old fridge so well, in fact, that I'm worried because it was drawing 114W this morning and I know the last time I measured it was 112W!
The Westinghouse has a clever design that makes maintenance quite easy. Four screws remove the freezer fan shroud and four more the fan itself. The coil tubing is far thicker than what is in the GE upstairs and the compressor about twice the size. It's much louder than the kitchen fridge, but the dogs don't mind! It also helps heat the basement in the winter, to further complicate the cost calculations.
My wife has never forgiven me for getting the new Sears washer because it constantly eats her stray unmentionables whereas the old one never did! She doesn't like the agitator, either, since it seems to tangle things more and clean less than the old one. Each time a twistup happens, she asks me "if you can keep that old refrigerator going for so long, how come you couldn't save that wonderful old washer?"
electromechanical
What I really need is a pressure relief bypass valve to deal with a clogged filter line like you find in profession filtration systems. The problem here is that we're talking about gravity feed! That made me think about how the ice dam forms and what it would take to build a sensor that "knew" it was encased in ice. I'd be afraid of trusting anything mechanical with a motor at low temperatures because of Challenger O rings and some years spent near Canada with a balky F-85. (-:
Am I right in assuming that two free air probes in a space right next to a coil will read a different resistance when encased in a block of condensate ice? I'm assuming dirty ice is a better conductor than pure ice. If ice accretes on the tubing first, and in a predictable way, could its expansion be counted on to let's say move an arm, as you suggest, but in doing so close a set of contacts? Still mechanical, but I should not run into any cold lubricant issues using contact closure.
I wish to hell I had taken pictures of the last freeze-up to get a better idea of how it forms. I caught it early this time, and just the bottom half of the coil was encased in ice. I believe an "open door freeze-up" is a far more uniform event, coating the coils evenly. I note this because a sensor at the top of the coils might not pick up an dirt-caused ice dam until it was almost frozen solid.
While taking a snack break, I thought about the whistling furnace filter and decided that if I inspected the elbow every time I changed a furnace filter, I would probably be OK. They are both downstairs and pretty near each other, so it's more a memory thing than anything else.
Then I decided to replace the elbow with some clear surgical tubing so I could see the condensate flow. I'll also add the milk jug of water at the back with a temperature probe. As per the suggestions of John and Dave I'll figure out how to process those fluctuations to sound an alarm. Better still, that input to my HA PC can be backed up by a cheap LCD with a max temp alarm. I need local, wife-comprehensible backups for anything like that. It's far easier to deal with a phone call that says "Honey, the thermometer on top of the basement refrigerator is beeping" than hoping she'll pay attention to my HA PC console beeping.
I'm going to consider this (mostly) solved although I'd really like to figure out how to detect coil icing. I can test the free air probe/resistance method pretty easily but there may be other options. IIRC, when my room A/C coils freeze up the first thing I notice is a tremendous increase in relative humidity in the air coming out of the AC. That might offer a clue as to detecting it in a freezer.
-- Bobby G.