12 of 20
All ProMelt systems will have fluid exposed to tempera-
tures below freezing and will use propylene glycol to
prevent the system fluid from freezing. The level of freeze
protection will depend on the glycol concentration used.
If the system is to be filled and commissioned during
freezing conditions, it is strongly recommended that a fill
cart be used to fill the system with pre-mixed anti-freeze
solution. Pre-mixing glycol with distilled water in the
proper ratio is always the preferred method of filling the
system. Be certain to follow the glycol manufacturer’s
instructions for mixing, testing and maintaining the an-
ti-freeze solution.
Annual Glycol Maintenance
A glycol system should be checked for two things:
system pH and freeze protection. The quickest way to
check a glycol system’s pH is with litmus paper. If the
pH drops below 7, then more buffers must be added to
a system or the system needs to be flushed and refilled.
There are only a limited number of times buffers can
be added to a system before it must be flushed and
replaced. Check with the glycol manufacturer for further
details. Some glycol manufacturers will require a higher
minimum pH to be maintained.
The second item that must be checked in a glycol
system is the actual
level of freeze protection
provided. Watts recom-
mends a 30-50% glycol
solution. However, a
50% anti-freeze solution
and 50% water does not
always equate to a 50%
solution. Different glycol
providers supply different
concentrations of glycol
and/or may mix a certain
amount of distilled water
with the inhibitors.
The only way to accurately measure the percentage of
glycol in a system is to use a refractometer. A refractom-
eter determines the freeze point of a liquid by measur-
ing the angle through which light is bent (the angle of
refraction) as it passes through the liquid. This angle
is a direct correlation to its freeze point, and should
be checked before and after the glycol is added to the
system. Check a sample mixture of one cup glycol and
one cup water. Test this solution with the refractome-
ter to see what the system freeze protection will be. Do
this each time the system is re-filled with new glycol.
Also, check the freeze protection when the system pH is
checked just to make sure the system is operating within
the desired parameters.
10
0
-10
-20
-30
-40
Refractometer
System Commissioning and Maintenance
When using the ProMelt 399 panel, typically only the
snow melt side of the heat exchanger (connected to the
snow melt manifold) is filled with anti-freeze solution.
NOTICE
Glycol Basics
Glycol is naturally corrosive. Buffers and inhibitors are
added to offset this corrosive effect. In addition, glycol
acts like an “oxygen grabber”, absorbing any free
oxygen molecules in the system. The more oxygen the
glycol “grabs”, the more acidic it will become.
Systems should not be
operated at levels below
30% glycol. Glycol
levels below 25% do
not contain enough
corrosion inhibitors and
may cause the glycol
to act as food, allowing
microbes to grow. These
microbes feed, grow and
die, creating a black sludge material in the system.
Propylene glycol concentrations above 25% prevent
microbial growth. It is recommended to not use a
concentration greater than 70% as the fluid may become
too viscous (thick) for the circulators.
As glycol in the system ages, the inhibitors and buffers
contained in the system begin to break down. This
process slowly returns the system to the natural pH level
of the glycol. If not properly maintained, glycol will cause
corrosion. Check a glycol system at least once a year to
ensure the glycol is still within its operating parameters.
