Re: Refrigerator monitor ideas?

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Dan Lanciani" <ddl@danlan.*com> wrote in message
news:1338510@xxxxxxxxxxxxxxxxxxxxxx
> In article <KvidnYy2RcSdP1nYnZ2dnUVZ_ternZ2d@xxxxxxx>,
ROBERT_GREEN1963@xxxxxxxxx (Robert Green) writes:
>
> | I *did* have a professional come out to look at it when we
> | first moved in.  He absolutely assured me the compressor was shot and I
> | needed either a new compressor or a new refrigerator.  I was going to
scrap
> | it at that point, but I took it apart, noticed the coil freezeup,
cleaned
> | the stuck drain tube and let it sit.  When I started it up again a day
later
> | it was fine.  So much for the advice of "professionals."
>
> Some years ago I made the mistake of replacing a 1959-vintage stainless
> Tappan with a (supposedly) "top of the line" efficient KitchenAid.  The
> first things I noticed were that the compressor ran almost all the time
> and the temperature in the refrigerator section varied wildly.  It was
> necessary to tweak the controls depending on ambient temperature and even
> if you got it right for a particular pattern of use, leaving it for a few
> days without opening the door would result in things freezing.  The repair
> folks claimed that this was all normal and a result of the high
efficiency,
> achieved in part by sizing the cooling system with minimal capacity
required
> for steady-state operation.

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.

> I can buy the efficiency argument, but I'd rather sacrifice a little
> efficiency to have the reserve capacity to bring the temperature back
> down quickly.  Moreover, the poor temperature regulation was not mainly
> a function of the "efficient" design.  The real problem was that cooling
> of the refrigerator section was achieved by a constantly running fan that
> blew cold air from the freezer section through a manually adjusted baffle.

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.

> The compressor cooled only the freezer directly and was controlled by a
> thermostat in the refrigerator.  Lack of active control of the fan and
> baffle was bad enough, but to top things off the thermostat was right in
> the path of the cold air entering the refrigerator from the freezer.  All
> of this struck me more as cost-reduction and poor design than efficiency
> improvement.

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.

> That refrigerator lasted about seven years during which an
> extended service contract (unusually) paid for itself.  Every major part
> (including the compressor at least? once) had to be replaced.

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!

> I replaced the KitchenAid with a SubZero which was very expensive but
> which has entirely separate cooling systems for the refrigerator and
> freezer sections.  In retrospect the Tappan must have been a very clever
> design.  It had only one compressor but there was no air path between
> (bottom) freezer refrigerator sections.  I'm pretty sure that it had
> coils in both sections, though people keep telling me I must have imagined
> this.  However it worked, it worked well...

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?"

> Getting back to your problem, I might be inclined to try an
electromechanical
> solution.  Could you arrange a slow-moving arm (motor geared way down) in
> the area where the ice dam forms?  When the arm ices up the motor stalls
> (or a clutch slips) and this can be detected.  As a bonus it might help
> slow the formation of a blockage in the first place.

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.