On Fri, 28 Aug 2020 22:00:17 +0100, Adrian Brentnall wrote:

I must confess I'm not confident in the RPi's ability to run things like
kiln controllers, which need to run, unsupervised, for 8 - 10 hours at a
time, often overnight.

Hum, have more confidence....

pi@PiZ-StoveB:/etc $ uptime
10:04:57 up 73 days, 9:38, 1 user, load average: 0.76, 0.63, 0.52

A Pi Zero (sans WiFi or Bluetooth) running a python script to control
the speed of the pump for the circulation between woodburner and
thermal store. The aim is to maintain a few degrees difference
between flow and return irespective of the actual temperature values
and if the woodburner is going flat out or dying down. Flat out it
boils rather too easyly...

Has half a dozen or so 1-wire devices connected that it monitors over
two 1-wire buses, an SSR using PWM to control the pump speed on a
GPIO, a small graphical LCD display SPI IIRC, (ex Nokia phones) to
show what it's up to and provide a menu system for set up controlled
by a rotary encoder on three GPIOs. Ethernet port via an ENC28J60
SPI(?) board.

It's also running nginx as web interface to the logged stove
temperatures pump speed etc (may also at some point, provide a
webinterface to the stove control script) and PiHole to block web
advertising crap for the LAN.

For me - the RPi is just too 'full-featured' - it's go too much going on
within the o/s for me to trust it to keep its mind on the
kiln-controlling job.

OS is Raspibian Lite (buster) so no GUI, completly headless, no
monitor, keyboard, mouse. Only way to talk to it is via the command
line from SSH over ethernet. The display/rotary controller is
confined to the menu system of the stove control script.

But then my background is real-time, safety-critical systems....

There is "real time" as in must react within 10 ns and and "real
time" as in must react within a minute... The stove system is slow to
react, pretty sure the period between each temperature measurment is
a minute. I suspect your kiln is also suitably "laggy".

--
Cheers
Dave.