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Table 9. Water quality guidelines (continued)
Element/Compound/Property
Hydrogen Carbonate (HCO
3–
2–
(HCO
)/(SO
)
3–
4
(Ca + Mg)/(HCO
)
3–
Chloride (Cl-)
Notes:
1.
Total Hardness/corrosion: Water with high hardness can cause
corrosion problems due to its high ion content (Ca+2, Mg+2, Fe+2)
which also means a high electrical conductivity and a high total
dissolved solid (TDS). For this reason, too high hardness values
should be avoided, not only due to higher risk of scaling, but also for
corrosion risk. On the other hand, soft water, but not necessarily
cation exchange softened water, may in contrast have a low buffering
capacity and so be more corrosive. If the hardness values are
outside the recommended range, other parameters such as oxygen
content, conductivity, and pH values should be considered to
evaluate the corrosion risk.
2.
Fe3+ and Mn4+ are strong oxidants and may increase the risk for
localized corrosion on stainless steels in combination with brazing
material copper.
Table 10. Glycol performance impact factors
Range Factor
Propylene Glycol Concentration
Lowest Ambient Temperature
Recommended Minimum
Leaving Fluid Temperature
Leaving Temperature
70°F (21°C)
60°F (15.6°C)
55°F (13°C)
50°F (10°C)
A 20% to 50% solution of glycol should be added to
prevent pipe corrosion regardless of the fluid temperature.
Propylene glycol has corrosion inhibitors that protect piping
and components from corrosion and buildup of rust and
other deposits. Trane recommends against using water/
glycol solution in excess of 40% regardless of the ambient
temperature conditions.
NOTICE
Equipment Damage!
Failure to follow instructions below could result in
permanent damage to pump and internal cooling
surfaces.
Do not use automotive antifreeze.
ARTC-SVX009A-EN
Value/Unit
60 – 200 ppm
> 1.5
> 0.5
< 200 ppm
Glycol Concentration Percentages and Performance Impact
30%
10°F (-12°C)
25°F (-4°C)
Capacity
Pressure Drop
Reduction Factor
Factor
0.96
1.27
0.95
1.31
0.95
1.31
0.94
1.33
Monitor Water Quality
Maintaining water/glycol mixture quality and cleanliness is
critical to heat pump health and maintainability. Strainers
should be checked and cleaned on a regular basis. Water/
glycol mixture samples should be taken and tested by a
professional lab. The results will enable the accurate
adjustment of quality thereby increasing the operational life
of the heat pump.
Note: Trane will not validate the heat pump warranty if the
proper water/glycol mixture composition and quality
is not maintained.
Maintain Glycol Level
The temperature of the refrigerant in a brazed-plate
evaporator is not uniform throughout the heat exchanger.
The refrigerant temperature is approximately 6°F to 12°F
colder than the corresponding fluid temperature depending
on many factors such as the heat exchanger design, glycol
percentage, operating fluid temperatures, refrigerant,
system flow rate, etc. When the heat pump has a set point
that is within 12°F (6.7°C) of the freezing point of the water/
glycol in use, take precautions against freezing. See
10, p. 43
for the recommended glycol concentrations and
performance impact.
40%
-4°F (-20°C)
10°F (-12°C)
Capacity
Pressure Drop
Reduction Factor
Factor
0.93
1.43
0.92
1.47
0.92
1.50
0.91
1.51
Note: If glycol-free solutions are mandated at the heat
pump site, special inhibitors are available for rust
prevention, mineral deposit inhibition, and biological
suppression. Adding these inhibitors to the water
solution is strongly recommended.
Heaters, heat tracing cable, and closed cell insulation can
be installed on any exposed "wet" heat pump components
for protection against freezing in low ambient temperature
and low refrigerant pressure conditions. However, the best
freeze prevention is using the appropriate concentration of
glycol. Trane does not warranty any component that fails
due to freezing.
Operating Procedures
Table
50%
-20°F (-29°C)
-10°F (-23°C)
Capacity
Pressure Drop
Reduction
Factor
Factor
0.91
1.63
0.90
1.68
0.89
1.73
0.88
1.75
43
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