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gbwillson

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Reply with quote  #31 
Personally, I don't see a need for an infinite speed control. But I would love to have a high/low speed control. It can be done to a certain extent with a second fan and second snap switch. With only two fan speeds, and appropriate temp probes, a reasonably accurate picture of BTU output would seem far easier than one with a fully variable fan speed. In either case, the programing alone is beyond my ability, so kudos to you Willie. 

Greg in MN

stmbtwle

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Reply with quote  #32 
You're probably right.  Multiple fans or a 2 or 3 speed fan.  

You could make an adjustable two-speed fan easily enough, with a single-speed fan, speed control and a couple of snap switches.  first switch turns it on. Use the speed control to manually adjust your low speed; the second switch bypasses the control and gives you high speed.

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stmbtwle

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Reply with quote  #33 
Btu measurement is easy enough for me as I measure the water output temp rather than air (there is no air output). Anyway air btu will be reflected in the water temp. My interests are more in control than logging. They're completely different cats, though they can be integrated.
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Willie, Tampa Bay
Rick H Parker

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Reply with quote  #34 
Whole lot easier to get a reasonable calculation of the energy content of water because the density of water is pretty stable. 
Air is a different story, density is effected by Temperature, Pressure, Humidity and Altitude.


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Rick H Parker
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stmbtwle

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Reply with quote  #35 
Yes, except the water method doesn't work very well on air collectors...
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Rick H Parker

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Reply with quote  #36 
What I'm saying is, one need more measurements to do Air Thermal energy calculations then one needs for water.
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Rick H Parker
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stmbtwle

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Reply with quote  #37 
There ARE a lot of variables but most of them don't change that much in a given location.

It really depends on how accurate you want to be, and I think most of us try to our testing under the approximately the same conditions anyway, which is why we do side by side testing when we can. You don't see us trying to compare a collector in Florida in July with one in Montana in January, though in theory it could be done.


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Willie, Tampa Bay
Rick H Parker

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Reply with quote  #38 
Hum ... I don't know of any location where the sum of Temperature, Barometric Pressure and Humidity variances is insignificant.

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Rick H Parker
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stmbtwle

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Reply with quote  #39 
As long as your testing minimizes the variations, they are. Serious testing does that and also uses a standard light source, so the experiments are repeatable. That's why we have "standard" conditions.



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Willie, Tampa Bay
stmbtwle

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Reply with quote  #40 
I'm at the stage now where it works and I believe will work well. But until I build an air collector (that I have no use for) I can't do a real-world test. I do have an ARETHA I want to rebuild and may put it in that, but an ARETHA is a different breed of cat.

At the moment I'm looking for:
1. A place to park the files (suggestions welcome) 'cause it's too big to put in a post at 100+ lines.

2. Constructive comments and ideas re what kind of bells and whistles. Besides the speed control, there is also provision for a vent servo control, 2 relays (for whatever use), and a second temperature sensor for differential control. But without suggestions or ideas I'm shooting in the dark. I'll send the file to anyone who wants it.

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