Water System Quality - Daikin Enfinity Installation And Maintenance Manual

Water System Quality

The cleaning, flushing and chemical treatment of a water
source heat pump system is fundamental to efficient operation
and the life expectancy of the system.
Potential system problems produced by the use of water fall
into three general categories:
• Scale formation – Mineral deposits which result from the
crystallization and precipitation of dissolved salts in the
water. The deposits form an insulating barrier, reducing the
heat transfer rate and impeding the circulation of fluids due
to increased pressure drop.
• Corrosion – Decomposition of the metal caused by
absorption of gases from the air. Corrosion may occur in
any metal component of the system.
• Organic growths – Slime and algae which form under
certain environmental conditions, and can reduce the
heat transfer rate by forming an insulating coating or can
promote corrosion by pitting.
Table 3: Water quality conditions & applications
Potential Problem
Scaling Calcium & Magnesium Carbonate
Ammonia, Ammonium Hydroxide
Corrosion Ammonium Chloride, Ammonium Nitrate
Calcium Chloride/ Sodium Chloride
Biological Growth
Erosion
Notes: 1. Water hardness in ppm is equivalent to hardness in mg/L.
2. Grains/gallon = ppm divided by 17.1.
3. Copper and cupronickel heat exchangers are not recommended for pool applications for water outside the range
of the table. Secondary heat exchangers are required for applications not meeting the requirements shown above.
4. Salt water applications (approx. 25,000 ppm) require secondary heat exchangers due to copper piping between the heat
exchanger and the unit fittings.
IM 1059-12 LARGE VERTICAL WSHP
Chemical(s) or Condition
pH Range
Total Dissolved Solids
Chlorine
Hydrogen Sulfide
Iron Bacteria
Iron Oxide
Suspended Solids
Water Velocity
The system water should be evaluated for degrees of impurity,
with testing available from independent testing labs, health
departments or state agencies.
Table 3 is a list of water characteristics, the potential impurities
and their results and the recommended treatment.
Avoiding Potential Problems
As shown in Table 3, all water contains some degree of impuri-
ties which may affect the performance of a heat pump system.
The use of a cupro-nickel coil can help avoid potential prob-
lems. Water flow rates should:
• Be high enough that the temperature rise through the heat
exchanger does not exceed 10° F when operating in the
cooling mode.
• Not exceed 4 GPM per nominal ton. Flow rates that have
velocities of 10 feet per second or more may cause pipe
erosion and heat exchanger failure.
Range for Copper Heat Exchangers
Less than 350 ppm
7 – 9
Less than 1000 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 125 ppm
Less than 0.5 ppm
None Allowed
None Allowed
Less than 1 ppm
Less than 10 ppm
Less than 8 ft./s
20
u i
nit nstallation
Range of Cupronickel Heat Exchanger
Less than 350 ppm
5 – 9
Less than 1500 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 125 ppm - Note 4
Less than 0.5 ppm
None Allowed
None Allowed
Less than 1 ppm
Less than 10 ppm
Less than 12 ft./s
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