Re: Refrigerator monitor ideas?

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>Anyway, IIRC there were lots of variations in coil temperature due to door
>openings, defrost cycles, power blips and more.  I'm assuming that your idea
>is to look for constant 32F readings on the coil indicating that it's a
>block of ice.  That implies a control system of some complexity, doesn't it?
>If I could find a cheap used pen recorder I'll bet that coil freeze-ups
>would appear distinctly differently after a few days of icing but that's
>still too late.  The ideal time to stop it is before an ice dam forms.

Actually, I was thinking more of monitoring the condensor coil temperature
which should rise steadily as the efficiency of the evaporator coil is
degraded by the ice.

I would think that if the temperature stays above some (unknown) point for
some (unknown) time it's a fairly strong indicator that something is amiss.
You might even simulate this by leaving the door ajar for awhile to get a
temperature profile to compare with a normal profile.

Then the logic is fairly simple. Measure the temperature every n minutes and
increment a variable if its above some (unknown) level and reset the
variable to zero if it's below that (unknown) level. If the variable reaches
x, sound an alarm. You might be able to do this with the logic in an Ocelot
(or CPU-XA) although I have to confess I'm not all that familiar with its
variables and timers. You might get help on the ADI forum.

I realize this doesn't provide the early warning you desire but I doubt you
are going to find any early warning methodology as the condensation will be
affected by relative humidity.

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