Water-Quality Considerations - Bosch CL Series Installation, Operation And Maintenance Manual

Water-Quality Considerations

7 Water-Quality Considerations
NOTICE
Failure to ensure proper water quality and flow rates can
shorten the life of the heat pump and potentially void the unit
warranty.
Maintaining proper water quality is required to ensure proper
operation of the heat pump. (Refer to the Water Quality Table
on page #28.)
For closed loop and boiler/cooling tower systems, water
chemistry must be checked and maintained to ensure that
corrosive elements, dissolved oxygen, and pH levels are kept in
check. It is important to be sure that any additive, antifreeze, or
corrosion inhibitor that is added to the water loop is compliant
with all applicable laws and regulations and is compatible with
copper, brass, and bronze alloys. Ensure that all recommended
safety precautions are followed when handling or adding
chemicals to the water loop.
For open loop systems, water quality is very important. Table 8
shows acceptable ranges for a variety of water quality factors.
The three main concerns in open loop installations are scaling,
corrosion, and fouling.
In installations with hard water, scaling due to a buildup of
carbonates on the heat exchanger wall can gradually degrade the
heat pump performance over time. Heat pumps that are affected
by scaling may exhibit low suction pressures in heating and high
head pressures in cooling with a gradual loss of capacity and
efficiency. Scaled heat exchangers can be cleaned by a qualified
technician but care should be taken to avoid scaling in the first
place. To limit scaling, water flow rates should be kept at
3 gallons/minute per nominal cooling ton (a 10°F temperature
rise in cooling) and care should be taken to avoid air in the water
lines from suction side leaks.
In installations with high hydrogen sulfide, chlorine or ammonia,
corrosion is a potential problem. In these installations a
cupro-nickel heat exchanger is required along with maintaining
proper flow and keeping air out of the system. If water quality is
outside of the values in the water quality table, then a closed loop
is required. Fouling due to iron bacteria can also pose problems
in some open loop installations. Iron bacteria fouling can quickly
degrade system performance and plug heat exchangers.
Air in the water system will greatly accelerate the fouling or
corrosion process.
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CL Series Heat Pumps — 8733838716 (2024/05)