Quote:
Originally Posted by Jazzoo
Stopped by my local pick-a-part yard and scored 8 hi and lo side sensors off late-model car AC units. I was in luck as the dealer was just starting to crush about 1000 cars and told me I could have what I wanted, as far as sensors go.
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Jazoo,
Great work. There may be a problem with sensors built for R-134a, but we won't know until we try.
Can you spost some photos of the sensors? Where in the car are they located? Did they just come off with a wrench?
Quote:
Originally Posted by Jazzoo
As far as the multiple sensor "branches" you want to run. There is a HUGE amount of 1-wire source for the AVR. Multiple branches could easily be handled by a single AVR acting as Master.
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This is very good news...
Quote:
Originally Posted by Jazzoo
I plan on implementing either a AtTiny13 or an MSP430 as a combo Pressure and Temperature 1-wire slave; as an initial trial. This is assuming the sensors I picked up today show to be of practical use.
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I checked out the ATTiny13, looks good. Have you looked into the
Teensy Development Board?
You can use it with the Arduino environment or WinAVR.
Quote:
Originally Posted by Jazzoo
In closing, I was wondering if you had thought of the start-up and shutdown procedures for your GSHP. For instance, you have ~200 feet of loop containing ~190 gallons (3/4" pipe) of water/solution (~8.3 lb/gal) traveling at 3 ft/sec. I could be way off here, but if M*V=I then (190*8.3) * 3 = 4731ft/lb. again I could be way out. If you were to instantly shut off the pump, would this not cause undue wear on the pump? In addition if you shut off the pump at the same time you shut off the compressor, do you not also have heat that would go "unused". My unit both gradually reduces the speed of the loop (over ~30 seconds) and has a "cool down" period (~2 min.).
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I have thought about the 'cool down' part, I recognize the advantage of prolonged circulation of the the warm fluid.
I hadn't thought so much about having a soft stop. I may be wrong, but I think that centrifugal pumps don't have a problem with hard stops, because the fluid can continue to push on through after the pump stops.
And how would you create a soft stop?
I'll be around intil tomorrow evening, then I will be out of touch for a week and a half, retreating to a sunnier clime.
I should return and be back online by Feb 15 or 16.
Thanks for your work.
Be well,
-AC_Hacker
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