Oil-filled loops must never be flushed with water. Water is a
contaminant that can never be completely removed.
Reinhibiting glycol-based fluid is usually only practical when the system has over
250 gallons of fluid in the collector loop. Reinhibiting requires professional analysis
of the current condition of the fluid, and careful determination of the amount of
inhibitor to add to the fluid.
Depending on the inhibitor being used, it may be possible to add inhibitor directly
into the system with a charging pump. In other cases, it may be necessary to drain
out five or ten gallons of fluid from the system, mix this with inhibitor, and return the
fluid to the loop. In either case, it will be necessary to recharge the system,
following the instructions near the end of this subsection.
Some inhibitors, such as dipotassium phosphate, do not dissolve in glycol. They
must be mixed with pure water, then introduced into the system, or into the rest of
Glyco/water mixtures must include inhibitors to retard
corrosion. Without proper inhibitors, these fluids rapidly become
corrosive and damage the piping systems.
Draining and Flushing Glycol and Drainback System Collector Loops
Ideally, a drain port is in place at the lowest point of the system. Open and drain the
used glycol or water.
Small amounts of glycol trapped in low points of the loop that are in the flow can be
left undrained. However, fluid in "dead legs," such as expansion tanks, must be
drained out. This may require cutting into the piping or unthreading joints, but it
must be done to avoid contaminating the new fluid.
5.2 REPAIR PROCEDURES