Leaking soldered joints must be repaired with a high-temperature solder, not 50/50
(Tin/Lead)! 95/5 (Tin/Antimony) can be used on all copper to copper joints. Joints
involving bronze should be repaired with 96/4 (Tin/Silver) solder. The use of 50/50
will result in joint failure within a few months, and may violate plumbing code.
Glycols and oils will burn when exposed to soldering torch
flames. Always drain the collectors before un-soldering joints!
Before heating the joints, remove the air vent, to allow fluid vapors to
escape. As the joint comes apart, be prepared for a brief flare. Keep
a fire extinguisher with you- not down in the truck!
Threaded joints in piping filled with glycols or synthetic oils must use teflon-based
thread sealants. Teflon tape, or Rectorseal #100 are two good choices. The only
appropriate sealant for threads exposed to silicone oils is fluorosilicone.
Brazed joints, and flared or compression fittings are all acceptable, but are rarely
used because they are less convenient than soldered or threaded joints.
Be sure to completely reinsulate the repaired piping.
Normally, valves with leaking stem seals can be repaired by tightening the packing
nut. If the leak is caused by an incompatible solar fluid, the valve should be
replaced with one with more compatible materials.
Leaks at valve inlets or outlets should be repaired the same way other leaks are.
Be careful to drain the solar fluid before applying a torch flame. Do not overheat the
valve and warp the seat or damage the internal seals.
Follow the recommendations for thread sealants and solder types in the preceding
section. If one valve or piping component in a loop is leaking, it may be worthwhile
to replace all similar units in that loop while the fluid is drained.
5.2 REPAIR PROCEDURES