Usually, water is "softened" to remove scale-causing "hardness." Typically, this is
done with ion-exchange softening equipment. Test for hardness with any standard
water hardness test equipment.
Sometimes iron creates problems by building up on the inside of piping systems and
reducing flow rates, and by giving the water a poor appearance and taste. Standard
ion-exchange softeners, specialized iron filters or chlorine-based treatments are
used to remove iron. These can all be easily checked with a test kit for total iron
(both ferrous and ferric iron).
Drainback systems normally use distilled or deionized water.
Glycol-based fluids should be checked for glycol concentration and the condition of
the corrosion inhibitor. If these two cannot be checked, at least check the pH
(acidity/alkalinity) of the fluid.
To check glycol concentration, some manufacturers (including Dow Chemical
Company) furnish simple test kits with simple test strips and color charts
(Figure 3-1 5). Another method is an optical refractometer (Figure 3-1 6). Both these
methods require only a few drops of fluid and are quite simple.
To check the condition of the corrosion inhibitor, measure either the pH or the
reserve alkalinity of the fluid. Most glycol manufacturers recommend that the pH
should not drop below 6.0 and the reserve alkalinity should not drop below 8.0.
Should either condition be too low, the fluid must be replaced or reinhibited.
To check the pH, use pH paper or tape, or have a laboratory analyze the fluid. If
using pH tape, use fairly fresh tape with a pH range from 6.0 to 8.0. Water
treatment specialists or swimming pool chemical suppliers are good sources for pH
To check the reserve alkalinity, use a special test strip from the manufacturer, or
have a lab check it. Some glycol manufacturers offer free testing for systems using
large amounts of fluid (over 50 to 200 gallons).
The, color of most glycol-based solar fluids is not usually a good indicator of fluid
condition. However, if the fluid appears and smells "burnt," or has visible sludge, it
should be replaced after the system is flushed out.
3.1 INSPECTION PROCEDURES