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Heating system hysteresis and efficiency

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GlennSprigg:

--- Quote from: paulca on February 02, 2021, 01:42:37 pm ---
--- Quote from: GlennSprigg on February 02, 2021, 12:48:11 pm ---Although (as some people mentioned) P.I.D. (Proportional, Integral
& Derivative) controllers can 'smooth' things out and make cooling/heating valves more efficient, 'Hysteresis'
is most important in that regard when it comes to energy saving!  (More on that shortly)...

--- End quote ---

PID controllers.  They are value homing mathematical based systems aren't they?  Like whatever that thought experiment was, that if you divide the distance you have to travel by 2 each time, you will always be half way to go.

So I imagine PIDs try to turn things up when the delta is high and slowly back off towards zero and the delta "approaches 0"? 

I'm not good with Calculus how did I do? . . .


--- End quote ---

Sorry about the delay...  Yes, you are absolutely right, and no 'calculus' needed !   :)
Just so that you know, the 'PID' (Proportional, Integral, Derivative) nomenclature is relating to the 3 main types
of control of 'valves' etc. that can be used/available within a 'controller'. Some may use only 1, or may utilize all 3.
As well as simple 'on/off' control, often/usually it is a variable output, which typically uses a 4 to 20 mA for control.
Proportional, is self explanatory. Integral, (in basic terms), slowly increases/decreases in timed 'steps'. However,
the Derivative action not only looks at the difference it is from set-point, but senses how 'rapidly' it is approaching
set-point!! and starts actually backing off before it gets there, so there is no resultant over-shoot!   8)

P.S.  Using 'current' in a systems loop is good, as it's the same everywhere in the loop through devices, unlike
using voltages. And starting at 4-mA (for zero!) brings devices/sensors.controllers into the linear part of the curve.  ;D
To quote a line from a Folk Song that I play... "It's all fun and games, until somebody loses an eye!"...  :scared:

paulca:
Thanks.  Sounds very 1960s. :) 

But the software equivalent is much the same.  The trendy thing is to use machine learning for these things, but that's one area I haven't really done much development with.

Like you let it run the heating with a default and allow it to evaluate how it did, then adapt the values, discarding any adaption which made things worse.  Over time it should learn the best way to manage things and as the situation changes it will slowly adapt with it.

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