Make-Up Water Systems
If glycol-filled loops are equipped with automatic water make-up, glycol can leak out
and be replaced by water. Eventually, the collector loop can freeze, causing severe
damage. If the make-up water system has a gate valve, it should be closed and
tagged so it will remain closed.
Leaks at gaskets, seals, valve stems, hoses, etc. may be occurring because the
rubbers and plastics are being attacked by the fluid. This is most common with
synthetic and silicone oils, but it also happens with glycols.
Use the table in Appendix E to determine if the fluid and materials are compatible.
This chart assumes the system is mostly copper tubing, and that relatively small
amounts of the other metals are used.
4.3.7 Piping Joints, Leaks in piping joints are not always obvious, since
they may be covered with insulation. The insulation may also "channel" fluid far
away from the actual leak.
A "phantom leak" may occur if an automatic air vent is used with glycols or oils. As
the fluid heats up, some of it vaporizes and leaves the system through the air vent.
These vents, if installed, should be replaced with manual vents. At the very least,
automatic vents should be tightly capped off during system operation, and then
replaced the next time the system is drained.
It has been found that improperly soldered joints can hold pressure in glycol loops
plugged the holes in the joint finally melts out, and a leak results.
Improper types of thread sealants may hold pressure for a few months before
leaking. Additional information on the use of thread sealants is provided in section
5.2.2 and Appendix E.
The use of 95/5 tin/antimony solder on bronze or brass fittings may cause the zinc
to leach out of the fitting, causing porosity leaks. 96/4 silver solder should be used
If a large number of joints are leaking in the collector loop, find out if 50/50 solder
was used. This solder's melting point of 370F is too low for the collector loop.
Some plumbing inspectors have solder testers, and may be willing to test a sample
4.3 TROUBLESHOOTING OPERATIONS