piping, and within 1 inch of the collector housing. (Figure 3-7)
Snap switch sensors, used for signaling the approach of freezing temperatures in
draindown systems are usually installed in the lower, colder, sections of the
collectors. Some freeze sensors may be installed on exterior piping.
Finally, sensors must be covered thoroughly with insulation, so they sense the
absorber or pipe temperature, not the air temperature. Actual sensor testing is
covered in Section 3.1.7.
3.1.2 Exterior Piping.
Joint leakage may not be immediately obvious in exterior piping. Leaking fluid may
be trapped or absorbed by the insulation. Incorrectly used automatic air vents may
have allowed vaporized solar fluid to escape slowly enough to leave no evidence of
3.1 INSPECTION PROCEDURES