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    Old Sunland drainback system control (3 Posts)

  • solradman solradman December 1, 2011 @ 3:48 AM
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    Old Sunland drainback system control

    Does anyone happen to know who manufactured the differential control that was installed with the old Sunland drainback system installed in the early 1980's.  The control model is a W-990 and says's "Differential Temperature Control".  Also any idea as to weather it used 3K or 10K sensors. 
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  • Paul Rohrs Paul Rohrs December 1, 2011 @ 5:14 PM
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    Quick Google Search

    I googled W990 Solar Control and came up with a website that said it was made by Webb.
    http://www.conifer-solar-consulting.com/Webb-990.pdf
    Attached is a PDF.  Page 8 shows the ohms resistance of the sensors.
    Best,

    Paul
    Webb-990.pdf
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  • hot rod hot rod December 6, 2011 @ 10:00 AM
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    looks a bit like

    the old Heliotrope.  I think those were built in California however?
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