Linux at 25

Chuck Guzis cclist at
Thu Sep 15 11:32:53 CDT 2016

On 09/15/2016 07:54 AM, tony duell wrote:

> My thermostat contains about 2 dozen parts, even if you count every
> nut , bolt, and washer. It does the job and is not hard to understand
> or repair if/when it needs it.
> Quite why I would want a thermostat with presumably several million
> components, running a multi-user operating system is, to be honest,
> beyond me.

(I don't mean to divert the thread stream; this is an explanation of why
an IOT-connected unit wound up on my wall)

It was a necessary (according to the installer) move as part of having
my home's 24-year-old heat pump replaced.  In that period, the US EPA
has been in the picture very actively.   The old R-22 refrigerant units
are becoming a liability with ever-stricter restrictions on replacement
refrigerant and technical certifications for handling.  By 2020, dealing
with them will be nigh impossible.  The nature of failure of my own
system was such that repairing it was impractical.

The thermostat cable for the old one was the standard 7 wire hookup; the
new system uses (IIRC) 9.  Given the  expense of pushing a new cable
through  finished walls and ceilings, a simple cable upgrade would have
been prohibitively expensive.  So a new 2-wire thermostat was employed
instead (at the installer's expense) and it has WiFi, Web and Bluetooth
connectivity as part of the package.  Fortunately, all of the
aforementioned can be disabled via appropriate selection on the (color)
LCD graphic touchscreen.

The previous heat pump started out with the usual mercury-switch bimetal
thermostat--at some point I upgraded to a programmable electronic one
and hoped to keep it.

As an aside, I just about fainted when I saw the controller electronics
for the heat pump.  Boards full of SMT; lots of  it.  On the other hand,
the unit does boast a lot of efficiency improvements and is very quiet.
What with EPA regulations now, the old "builder's model"
no-frills-barely-does-the-job units seem to be a thing of the past.


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