Puzzle: How to extract desired info from data?

On Jun 24, 4:23&#4294967295;pm, jim <"sjedgingN0Sp"@m@mwt,net> wrote:
> Rune Allnor wrote:
> > You missed the word 'trend' in the problem statement. I can't
> > get the numbers from these kinds of estimates, but you *can*
> > get a rough idea about at what times the heater does hard work,
> > and when it relaxes.
>
> Your question should have been
>
> Q: How does one avoid getting an estimate of power consumption
> &#4294967295; &#4294967295;trends in the heater, from this set-up?
>
> A: don't look at the data

Do you have an alternative?

Rune

On Jun 24, 4:57&#4294967295;pm, Jerry Avins <j...@ieee.org> wrote:
> On Jun 24, 1:28&#4294967295;am, Rune Allnor <all...@tele.ntnu.no> wrote:
>
> > On Jun 23, 4:36&#4294967295;pm, Jerry Avins <j...@ieee.org> wrote:
>
> &#4294967295; ...
>
> > > You know neither how much power is delivered when the heater is on nor
> > > how much is lost to ambient when the power is off. You know nothing
> > > about additions or removals from the vat. How do you calculate energy
> > > (which is what I thout you asked) or power (which is what you seem to
> > > want)? What have I missed?
>
> > You missed the word 'trend' in the problem statement. I can't
> > get the numbers from these kinds of estimates, but you *can*
> > get a rough idea about at what times the heater does hard work,
> > and when it relaxes.
>
> > Which is just enough to correlate with measurements of other
> > external factors one might suspect influences the system.
>
> Because of the "dimmer", you can't know how hard the heater works.

Correct.

> How
> does knowledge of the heater's duty cycle imply its power?

It doesn't. But if the dimmer is never touched, the power
trends can be determined to within a scale factor.

> The system
> needs calibration.

Can't get that.

Rune

On Jun 25, 1:03&#4294967295;pm, jim <"sjedgingN0Sp"@m@mwt,net> wrote:
> Jerry Avins wrote:
>
> > On Jun 24, 1:28 am, Rune Allnor <all...@tele.ntnu.no> wrote:
> > > On Jun 23, 4:36 pm, Jerry Avins <j...@ieee.org> wrote:
>
> > &#4294967295; ...
>
> > > > You know neither how much power is delivered when the heater is on nor
> > > > how much is lost to ambient when the power is off. You know nothing
> > > > about additions or removals from the vat. How do you calculate energy
> > > > (which is what I thout you asked) or power (which is what you seem to
> > > > want)? What have I missed?
>
> > > You missed the word 'trend' in the problem statement. I can't
> > > get the numbers from these kinds of estimates, but you *can*
> > > get a rough idea about at what times the heater does hard work,
> > > and when it relaxes.
>
> > > Which is just enough to correlate with measurements of other
> > > external factors one might suspect influences the system.
>
> > Because of the "dimmer", you can't know how hard the heater works. How
> > does knowledge of the heater's duty cycle imply its power? The system
> > needs calibration.
>
> Suppose this is a hot water heater and suppose he was trying to
> determine at what times of day hot water is used the most and when it is
> used least. Or suppose he wants to know if taking a shower in the
> morning &#4294967295;uses more hot water than doing laundry in the afternoon.
>
> I don't have any idea why there would be a &#4294967295;dimmer in the circuit.

Because we don't want to poke to hard on the system.
The ideal controller would be a PID. What we have
is an on / off thermostate.

Rune

On Jun 25, 10:58&#4294967295;pm, Jerry Avins <j...@ieee.org> wrote:

> Unless I misread, he writes that he wants to estimate power, not
> relative power.

Power *trend*. The word is in there.

Rune

On 6/26/2011 10:15 PM, Rune Allnor wrote:
> On Jun 24, 4:57 pm, Jerry Avins<j...@ieee.org>  wrote:
>> On Jun 24, 1:28 am, Rune Allnor<all...@tele.ntnu.no>  wrote:
>>
>>> On Jun 23, 4:36 pm, Jerry Avins<j...@ieee.org>  wrote:
>>
>>    ...
>>
>>>> You know neither how much power is delivered when the heater is on nor
>>>> how much is lost to ambient when the power is off. You know nothing
>>>> about additions or removals from the vat. How do you calculate energy
>>>> (which is what I thout you asked) or power (which is what you seem to
>>>> want)? What have I missed?
>>
>>> You missed the word 'trend' in the problem statement. I can't
>>> get the numbers from these kinds of estimates, but you *can*
>>> get a rough idea about at what times the heater does hard work,
>>> and when it relaxes.
>>
>>> Which is just enough to correlate with measurements of other
>>> external factors one might suspect influences the system.
>>
>> Because of the "dimmer", you can't know how hard the heater works.
>
> Correct.
>
>> How
>> does knowledge of the heater's duty cycle imply its power?
>
> It doesn't. But if the dimmer is never touched, the power
> trends can be determined to within a scale factor.
>
>> The system
>> needs calibration.
>
> Can't get that.
>
> Rune

Rune,

Well, at least this screen has time while I work on the others.

Having read all the stuff back and forth, it seems like the question:

"Q: How does one get an estimate of power consumption
    trends in the heater, from this set-up?"

Would first be interpreted as meaning:
How can you tell when there's a lotta power being used and when there's 
not?  After all, those would be the overriding "trends", no?

So, if estimating that from the duty cycle of the heater is good enough 
then, as you acknowledged, you detect the switch points from the temp.

It seems the interpretation of the question is important.  The 
combination of "consumption" and "trends" likely conflict in the brain 
even though there's nothing wrong with it.  I said above: "being used" 
without even thinking about it.

Fred