Install drain plugs as you repair the piping. Use teflon-based thread sealants.
Dispose of used glycol properly, according to local requirements. Consider reusing
non-toxic glycol (propylene glycol) for less critical applications, such as freeze
protection for drain traps.
If a fill/drain assembly similar to the one in Figure 5-26 is not part of the system,
install one. It can be placed in any part of the loop which contains the flow of all the
fluid, but an ideal spot is between the system low point and the return line coming
from the collectors.
(using check valve)
Normally a check valve is used, as shown. A gate or ball valve can be used
instead, but only if a working check valve is somewhere else in the loop. Having
two check valves in the loop is acceptable, since one can back up the other.
Make sure the seals and seat of the valves used are compatible with the glycol.
Use a teflon-based thread sealant.
Hook up a hose to a cold water line, and connect this to the "fill" fitting downstream
of the check valve. The arrow on the check valve will point to this fitting. Connect
another hose to the "drain" fitting, and run it over to a suitable drain. Use approved
methods to collect and dispose of used glycol solution.
5.2 REPAIR PROCEDURES