Johnson Controls RC Series Engineering Manual page 19

Application Notes cont.
Cooler/Boiler - Closed Loop
Water Quality
In ground water situations where scaling could be heavy or where
biological growth such as iron bacteria will be present, a closed
loop system is recommended. The heat exchanger coils in ground
water systems may, over a period of time, lose heat exchange
capabilities due to a buildup of mineral deposits inside. These
can be cleaned, but only by a qualified service mechanic, as
special solutions and pumping equipment are required. Hot water
generator coils can likewise become scaled and possibly plugged.
Material
pH Acidity/Alkalinity
Calcium and
Scaling
Magnesium Carbonate
Hydrogen Sulfide
Carbon Dioxide
Corrosion
Ammonia Chloride
Ammonia Nitrate
Ammonia Hydroxide
Ammonia Sulfate
Total Dissolved Solids (TDS)
Iron, FE
Iron Fouling Bacterial Iron Potential
(Biological Growth)
Iron Oxide
Suspended Solids
Erosion
Threshold Velocity
(Fresh Water)
NOTES: Grains = ppm divided by 17
mg/L is equivalent to ppm
Copper
(Total Hardness)
less than 350 ppm
Less than 0.5 ppm (rotten egg
smell appears at 0.5 ppm)
Sulfates Less than 125 ppm
Chlorine Less than 0.5 ppm
Chlorides Less than 20 ppm
Less than 50 ppm
Ammonia Less than 2 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 1000 ppm
LSI Index +0.5 to -0.5
2 + (Ferrous)
< 0.2 ppm
Less than 1 ppm, above this level
deposition will occur
Less than 10 ppm and filtered for
max. of 600 micron size
< 6 ft/sec
• Closed Loop /Cooler-Boiler Systems utilize a closed heat
recovering loop with multiple water source heat pumps in the more
conventional manner. Typically a boiler is employed to maintain
closed loop temperatures above 60°F and a cooling tower to
maintain loop temperatures below 90°F. These systems are
applicable in medium to large buildings regardless of whether the
load is heating or cooling dominated. Due to the moderate loop
temperatures, AHRI/ISO 13256-1 Water Loop Heat Pumps are
required for this application.
In areas with extremely hard water, the owner should be informed
that the heat exchanger may require occasional flushing.
Units with cupronickel heat exchangers are recommended for
open loop applications due to the increased resistance to build-up
and corrosion, along with reduced wear caused by acid cleaning.
Failure to adhere to the guidelines in the water quality table could
result in the loss of warranty.
90/10 Cupronickel
7 - 9 7 - 9
(Total Hardness)
less than 350 ppm
10 - 50 ppm
Less than 125 ppm
Less than 0.5 ppm
Less than 125 ppm
10 - 50 ppm
Less than 2 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
1000 - 1500 ppm
+0.5 to -0.5
< 0.2 ppm
Less than 1 ppm, above this level
deposition will occur
Less than 10 ppm and filtered for
max. of 600 micron size
< 6 ft/sec
19
RC SERIES ENGINEERING GUIDE
316 Stainless Steel
7 - 9
(Total Hardness)
less than 350 ppm
Less than 1 ppm
Less than 200 ppm
Less than 0.5 ppm
Less than 300 ppm
10 - 50 ppm
Less than 20 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
Less than 0.5 ppm
1000 - 1500 ppm
+0.5 to -0.5
< 0.2 ppm
Less than 1 ppm, above this level
deposition will occur
Less than 10 ppm and filtered for
max. of 600 micron size
< 6 ft/sec
2/22/12