Egzoset said:
Hi,
OF said:
It's not actually a thermostat... ... Anyway, what exactly did you see as the improvement to be made?
I'd be most curious to know what you are willing to call a thermostat as it would be quite difficult for me to find the right choice of words to proceed with the rest of your reply otherwise. Here's how i view thermostatic regulation in general terms:
http://oi43.tinypic.com/2z5k77p.jpg
Please explain how our definitions differ.
A thermostat is a mechanical switch. On or off. To work it has to have a "dead band". Consider your home heater. Say it's 60 degrees in the room and you set the thermostat for 70 so the heat comes on. The room warms up, reaches 70 and the heater shuts down. In the real world there's retained heat that needs considering, but for now let's ignore that part but assume the temperature is at least high enough above 70 to click the switch off. As cooling starts, what do you do? Can't switch back on at 69.9 degrees. So the solution is hysteresis (AKA 'dead band'). You actually shut off at say 72 degrees and then don't switch back on until it drops to 68. In your home unit, this is usually done with a magnet or in the old days a shift of the puddle in a Mercury switch. All in all, not all that stable nor responsive to changes like say opening a window.
Consider the curse control in your car with this system. Coast, then full throttle, then coast, then full blast.... We need something better for such systems. This is the sort of control used on HA (but not I think on most others). Like your car, it comes to temperature quickly through pure horsepower. The heater wide open would get into trouble. However, the
rate of rise is watched to anticipate the future. This is done dynamically, that is as it's actually happening by a computer. The best we can do in the thermostat system is to take a wild stab at it under given conditions. Advanced thermostats have an adjustable heater in them for this use that artificially heats the box a bit, called the anticipatator. It's adjusted on installation and left at that setting.
Anyway, in cruse controls and HAs the difference between what should happen (how fast, hot or whatever) compared to what is happening is a value not a yes/no decision and to this more advanced systems add a time related rate of change correction to this which then becomes a
proportional signal (not on/off) that controls the power. This allows your car to handle hills and dales as they happen and your favorite vape to not balk when you draw hard on it or overshoot badly when you quickly set it down. Way past thermostats. In fact about as good as it comes. PID controls (what we're talking about here) are pretty much state of the art. Once fitted properly the only possible improvement is in 'fine tuning' the system.
Like I said, all I see 'wrong' is maybe it should go a little higher in temperature? Otherwise it gets to temperature amazingly fast and holds it very well under changing loads as I see it. Hard to ask for more.
OF