Re: Refrigerator monitor ideas?

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"AZ Woody" <reply@here> wrote in message
news:45c67e52$0$25783$815e3792@xxxxxxxxxxxxxxxxx
> While I've been skipping much of this thread (too much bickering), one
> thing occurred to me...

I appreciate you wading through to at least add your input.  I found it
quite disappointing that a long-time poster would feed, clothe and house the
trolls.  Another one rides the twitlist bus, I guess.

> The problem seems to occur when the coils "freeze up" and defrosting
> doesn't occur or the drain tube is clogged.  When defrosting occurs
> normally, it's clear that the moisture will travel down a tube, into
> either a pan or a drain every day or so.

Exactly.  But it turned out to be more complicated.  In detailing the
mechanics of the condensate drain we have concluded (at least I have) that
there are two distinct causes of "coil freeze."  The most common two are
open doors or clogged drain pathways.

At first, I just wanted to detect just clogged drain tubes but discussion
indicates I should also "trap" open doors.  The issue now is what kind of
simple sensor(s) can detect a coil freeze caused by either event?

> What if you used a moisture sensor where the tube drains?  I'm thinking
> in particular, the type used as a rain sensor for an irrigation system.

The problem * may* lie in the fact that before an ice dam forms, the flow is
reduced but not completely abated.  The moisture sensor on the floor would
probably lag the coil freeze-up by so much time it would not be useful as a
preventative measure.

Another problem with the moisture sensors is that a coil freeze from an open
door causes refrigerators to whizz on the floor.  The condensate flow
triples in this case as the unit runs 24/7, but the drain tube is free and
the floor pan overflows.  The moisture sensor is deliriously happy. (-:

<stuff snipped>

> Adjust the trigger so that it only changes state if dry for more than a
> day (or what ever seems correct for your situation).
>
> Simple, with no controller involved, with delays based on how fast the
> sensor dries out, and adjustable...  And no worry about how often the
> door is opened...

It would probably make a good tertiary sensor and might provide useful
"normal operation pattern" information if I could log it easily.  It would
be nice to know exactly what readings precede a "coil freeze-up."  At some
point during an "open door" event the coil seems to freeze solid, even with
a clear drain tube.  I really want to know when the coils are forming a skin
of ice that can't be removed by the defrost coils.  That's kind of tricky.

--
Bobby G.