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data logger
I've been using an 8-channel data logger (software is DOS and Forth, not user friendly, but fun--any old astronomers here?) to collect data on the thermal performance of my home and trailers (I was mainly interested in how the various compartments, like the space behind the rear bath, did in comparison with inside trailer temperatures, as the outside temp fell below freezing). It takes about a day to construct the A-D board and check it out. I have 10 or so laptop-like PC-XT machines that I use for the logger (anyone got a crying need for one? They draw less than one amp.), but any computer with a parallel port can do the job. The output is a comma delimited text file that can be imported to Excel.
With 8 channels you can get a pretty detailed analysis of outside and inside ambient temps, skin temps, and thermal conductivity of the ribs, plus samples of several compartments, the most important I think would be behind the bath and under the sink. I intend to tackle this as soon as I get the skin back on my 27' 1972 (with Malcomium's foil insulation) and compare that to the performance of my stock 31' 1975 for this coming summer in the SW dessert. If anyone else wants to tackle this, let me know. I don't have a clue at this point how we'd normalize the data, but if several different insulating methods have been tried, I'd like to compare them.
I'm particularly curious about what we have discovered regarding best methods for underfloor insulation.
Here's some details on the data logger performance:
The data logger uses a Maxim ADC186, connected to the computer via the parallel printer port (+5 and +12 volts are required). The ADC provides 12 bit conversions. When an LM-135 is used as a temperature sensor, temperature is measured with 0.1ºC resolution. LM-135 accuracy affects only the slope of the temperature equation, so with only a single multiplication/division operation to adjust the slope, a highly accurate system is possible. LM-135 uncalibrated accuracy is generally on the order of 1.5% or better, but can be as poor as 5%. After calibration, long term accuracy appears to be within 0.3ºF or better.
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