Enertech Global
56
EAV - EME/EMD Rev. A Models
Installation and Operations Manual
Antifreeze Characteristics
Selection of the antifreeze solution for closed fluid systems
require the consideration of many important factors, which
have long-term implications on the performance and life of
the equipment. Each area of concern leads to a different “best
choice” of antifreeze. There is no “perfect” antifreeze. Some of
the factors to consider are as follows (Brine = antifreeze solution
including water):
Safety:
The toxicity and flammability of the brine (especially in a
pure form).
Cost:
Prices vary widely.
Thermal Performance:
The heat transfer and viscosity effect of
the brine.
Corrosiveness:
The brine must be compatible with the system
materials.
Stability:
Will the brine require periodic change out or
maintenance?
Convenience:
Is the antifreeze available and easy to transport
and install?
Codes:
Will the brine meet local and state/provincial codes?
The following are some general observations about the types of
brines presently being used:
Methanol:
Wood grain alcohol that is considered toxic in pure
form. It has good heat transfer, low viscosity, is non-corrosive,
and is mid to low price. The biggest down side is that it is
flammable in concentrations greater than 25%.
Ethanol:
Grain alcohol, which by the ATF (Alcohol, Tobacco,
Firearms) department of the U.S. government, is required to
be denatured and rendered unfit to drink. It has good heat
transfer, mid to high price, is non-corrosive, non-toxic even in
its pure form, and has medium viscosity. It also is flammable
with concentrations greater than 25%. Note that the brand of
ethanol is very important. Make sure it has been formulated
for the geothermal industry. Some of the denaturants are not
compatible with HDPE pipe (for example, solutions denatured
with gasoline).
Propylene Glycol:
Non-toxic, non-corrosive, mid to high price,
poor heat transfer in high concentrations, and potential for high
viscosity when cold (in high concentrations). It has also been
known to form a “slime-type” coating inside the pipe when
inhibitors are not used. Do not use food grade glycol, since it
does not include inhibitors. A 25% to 30% brine solution is a
minimum concentration for required inhibitors, depending upon
brand of glycol. If using a lower concentration (e.g. 20% provides
19°F freeze protection), additional inhibitors must be added.
Note that some states/provinces have toxicity requirements that
must be verified based upon the chemical composition of the
inhibitors.
⚠
CAUTION
⚠
HYDRONIC LOOPS MUST BE ANTIFREEZE PROTECTED.
INSUFFICIENT AMOUNTS OF ANTIFREEZE MAY CAUSE
SEVERE DAMAGE AND MAY VOID WARRANTY. HYDRONIC
LOOP ANTIFREEZE MUST BE NON-FLAMMABLE. NEVER
OPERATE WITH HYDRONIC LOOP FLOW RATES LESS THAN
SPECIFIED. CONTINUOUS OPERATION AT LOW FLOW OR
NO FLOW MAY CAUSE SEVERE DAMAGE AND MAY VOID
WARRANTY.
Section 7: Water Quality & Antifreeze
