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

QV Series Heat Pumps

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 QV series heat
pump. See the Water Qualify Table on page #24.
For closed loop and boiler/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 5 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.
QV Series Heat Pumps
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.
Subject to change without prior notice
Water Quality Considerations | 23
8733829041 (2021/07)