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© 2011 Aqua-Hot
®
450-D Hydronic Heating System Owner’s Manual
A
PPENDIX
C: A
NTIFREEZE
T
ERMS
AND
M
IXTURE
R
ATIO
The following information addresses the process of
selecting a propylene glycol based antifreeze solution
that provides adequate freeze, boiling, and rust/anti-
corrosive protection. A 50/50 mixture ratio is recom-
mended, which will result in a freeze point of approxi-
mately –28
⁰
F. and a boil point of approximately 222
⁰
F.
The following information should be utilized for the pur-
pose of clarifying some terms commonly associated
with antifreeze.
Freeze Point and Burst Point:
Antifreeze solution lowers the freezing point of any liq-
uid, to which it has been added, by preventing the forma-
tion of ice crystals; however, as the ambient temperature
continues to decline, the water in the solution will at-
tempt to attain a solid state. The point in which the wa-
ter begins to solidify is termed the “freeze point.” Al-
though the water in the solution has begun to freeze,
producing a “slushy” consistency, the antifreeze in the
solution will continue to combat the normal expansion of
the solution as it freezes. The point in which the solution
can begin to expand, due to colder temperatures, is
called the “Burst Point.” Once the solution reaches the
burst point, the potential is present for ruptured pipes to
exist. The burst point of the antifreeze and water heat-
ing solution is dependent upon the brand of propylene
glycol antifreeze employed.
A
PPENDIX
B: A
NTIFREEZE
M
IXTURE
W
ATER
Q
UALITY
R
ECOMMENDATIONS
In order to ensure maximum performance and longevity
of an Aqua-Hot heating system’s boiler tank and associ-
ated components, it has been determined that there is a
need to use distilled, de-ionized, or soft water in combi-
nation with concentrated propylene glycol for the Aqua-
Hot’s antifreeze and water heating solution. Please
note that this is only necessary when mixing concen-
trated propylene glycol antifreeze with water; suppliers
of pre-mixed antifreeze are responsible for the use of
high-quality (distilled, de-ionized, or soft) water when
preparing their antifreeze for sale.
Hard water possesses a high-level of calcium and mag-
nesium ions, which deplete the propylene glycol anti-
freeze’s corrosion inhibitors. This, in turn, causes the
antifreeze and water heating solution to begin turning
acidic, which can corrode the Aqua-Hot’s Boiler tank and
associated components prematurely. Therefore, con-
centrated propylene glycol should be diluted with dis-
tilled, de-ionized, or soft water which is 80 ppm or less in
total hardness. The local water agency should have up-
to-date water quality reports which should indicate if the
local tap water is within this guideline.
A
PPENDIX
A: A
NTIFREEZE
T
YPES
The following information addresses the necessary us-
age of a propylene glycol based “boiler” type antifreeze
in the Aqua-Hot. Propylene glycol is a safer alternative
to the more toxic ethylene glycol antifreeze; however, as
mandated by IAPMO (International Association of
Plumbing and Mechanical Officials), only those propyl-
ene glycol based “boiler” type antifreezes deemed
“Generally Recognized as Safe” (GRAS) by the FDA
should be utilized.
Because of the significant impact various types of anti-
freeze can have on a hydronic heating system, including
the level of safety provided, it has been recognized that
there is a need to provide an explanation regarding two
additional prominent types of antifreeze/coolant avail-
able. The following information should be utilized as an
educational means of ensuring that the proper type of
propylene glycol based antifreeze is selected:
RV & Marine Antifreeze:
These types of propylene glycol based antifreeze prod-
ucts are formulated specifically for “winterizing” applica-
tions only. Although RV & Marine antifreeze is often
“Generally Recognized as Safe” by the FDA, it should
never be used in the Aqua-Hot’s Hydronic Heating Sys-
tem. This type of antifreeze is not formulated to transfer
heat, which is essential to the heating system’s function-
ality and does not contain rust inhibitors. Please note,
however, that RV & Marine antifreeze can be utilized to
winterize the Aqua-Hot’s Domestic Hot Water Heating
System.
Automotive Antifreeze/Coolant:
These types of propylene glycol based antifreeze prod-
ucts are formulated specifically to protect automotive en-
gines against corrosion, freezing temperatures, and over-
heating. They also have excellent heat transfer and ther-
mal conductivity characteristics. Although these types of
antifreeze products are considered less toxic and safer
than ethylene glycol for people, pets, and the environ-
ment, they are not “Generally Recognized as
Safe” (GRAS) rated by the FDA. Therefore, they must be
marked with a “harmful if swallowed” warning. This addi-
tional warning is required because these types of anti-
freeze products contain high levels of chemical rust in-
hibitors. Due to their potentially hazardous properties,
they should never be used in the Aqua-Hot’s Hydronic
Heating System.
