Any heat exchanger with steel components exposed to fresh water must have a
sacrificial anode. If the anode is gone, or nearly gone, a replacement should be
obtained and installed.
If an exact replacement cannot be obtained, it may be possible to saw off a one or
two inch chunk of water heater anode and place it inside the shell. Use a standard
threaded plug to close up the port in the heat exchanger.
The heat exchanger and associated piping should be adequately and completely
insulated after repairs are made.
Leaks at seams in steel or stainless steel drainback tank shells can usually be
welded. Cracks at fittings or leaks in heat exchanger coils normally require
A common problem with drainback tanks is a low solar loop water level. With the
system off, add distilled or deionized water until the tank overflows. Tap water can
be used, but this should not be the usual practice.
5.2.6 Solar Fluids,
General Information About Draining and Flushing
It is not always necessary to drain the fluid from the system to "repair" it.
Sometimes, glycols can be restored to good conditions by adding corrosion
inhibitors. This "reinhibiting" can usually be done without completely draining the
If water is used to flush out debris or corroded particles from a loop which contains
glycol-based fluids, follow the instructions carefully about discarding the "hung-up"
water in the loop when it is refilled. Always dispose of used solar fluids properly, in
accordance with local requirements.
Oils contaminated with water or foreign matter can sometimes be cleaned up by
filtration, without draining the fluid.
5.2 REPAIR PROCEDURES