Quote:
Originally Posted by Jazzoo
Some of your purchases and reference to Strider3700’s thread seem to be going in two different directions. Strider3700’s thread and your purchase of “one-wire” temperature sensors (DS18 series?) indicate a desire to use “digital” sensors.
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I have (at least) four data logging/control projects in mind.
- GROUND MEASUREMENT - One would be to dig a hole as deep as my boreholes and bury a vertical measurement array, with temperature sensors every two feet. The frequency of the measurements would be about data reading one every two hours. It might be well to make ten readings within the two hour period and sum the result for subsequent division, to get a smoothed average. This would need to run for several years, and not lose data if house power was lost.
- WHOLE HOUSE - Another would be very similar to the whole house energy logging, pretty much as Strider is going about it. It would be nice if it could survive power loss, but not critical.
- HEAT PUMP TESTING - Another would be a data logger for the heat pump for the purpose of learning about how it works, and tweaking it for optimum efficiency. The expected run times would probably be pretty short, maybe a few days at the most.
- MACHINE CONTROL - The last, but most important, is a heat pump protection controller to minitor its performance and to shut it down if certain danger-points are reached. (If this controler could also monitor performance and envorinmental data and change certain settings, refrigerant flow to the evaporator, or circulation pump speed, or switching water flow from heating mode to cooling mode, for instance would be really cool, but that's in the future.)
[* EDIT (11-11-11): Since this post, an inexpensive controller with a web interface has been found. Xringer has posted a thread where he gives a pretty good introduction to the controller including sources of interface devices that make it very useful. *]
I bought a Sparkfun Log-o-Matic that I used for a DIY data logger. It does analog or digital reading, but not both. Then somebody named Kwan wrote a new firmware for it, and I believe that it will allow both. I've downloaded the Kwan firmware but haven't gotten around to trying it yet. I like it that I can use analog (which is good enough) or 1-wire which would give me extra sensors.
Quote:
Originally Posted by Jazzoo
My suggestion for using Automotive sensors is they are designed to work on a low system voltage in a very harsh environment. This works to our advantage two fold. One, they will likely interact with Micros’ such as the Atmel processor in your Arduino. Two, they should function reliably over the 20-25yr system life expectancy.
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Great thinking, just great.
Quote:
Originally Posted by Jazzoo
An area of concern, repurposing devices, are the chemical interactions at the physical contacts. I.E. Will the membrane in the Oil-Sensor react with the Refrigerant? This may not be the case, I don’t know. I’d be willing to wager that the Hi and Lo sensors from the AC would be a good match for the Evaporator, Condenser, and Compressor.
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I think that if mineral oil compatible refrigerants were used (R-22, R12, R-290), you would be correct.
Quote:
Originally Posted by Jazzoo
If it were my time and money I would get a PC to dedicate to the project. An older model with a serial port (DB9 or DB25). Can be had for free or nearly free.
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This would be really great for Heat Pump Testing, but not so good for machine control.
Thanks, James for all the good ideas and links!
Best Regards,
-AC_Hacker