Heat-conductive compound can be placed on the header and sensor before
placement. Two such compounds are General Electric lnsulgreaseTM or Honeywell
heat-conductive compound (Part #107408).
Make sensor connections by twisting the wires together, then twisting on small wire
nuts. After installing the wire nuts, fill them with silicone sealant. Tie a knot in the
wires for strain relief.
Be sure to insulate the sensor completely, to isolate it from the cold outside air.
Push the insulation up against the wall of the collector. Seal the joint between the
collector and the insulation with silicone sealant.
The wires running from the sensor should be protected from sunlight and high
temperatures. They must not be strapped directly to bare copper tubing. Secure
them to the outside of the pipe insulation, inside the insulation jacket.
To "tie" up the wires, use cable ties rather than tape. Do not use uninsulated
staples, as it is very easy to short circuit the sensor lines with regular staples.
The type of sensor wire which should be used is 18 to 22 gauge (minimum) multi-
strand twisted pair. The multi-strand will bend and flex without breaking. Twisted
pair wire is less affected by stray electrical noise. Cable exposed to sunlight or high
temperatures should have an appropriate jacket. Teflon is one good choice.
5.2.2 Interior and Exterior Piping.
All exterior pipe insulation `must be covered with adequate insulation and a
weatherproof jacket. This includes the short pipes between collector headers, and
the unused (and capped) headers (Figure 5-1 1).
Elastomeric insulations, such as ArmaflexTM or RubatexTM, do not require jackets,
but must be thoroughly painted or covered to protect them from UV radiation
5.2 REPAIR PROCEDURES