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8.3 Anti-Legionella function
8 Operation
8.3.1 General information
Legionella bacteria is commonly found in water. The bacteria mul-
tiply where temperatures are between 20 - 45°C and nutrients are
available. The bacteria are dormant below 20°C and do not survive
above 60°C.
Legionnaires' disease is a potentially fatal type of pneumonia,
contracted by inhaling airborne water droplets containing viable
Legionella bacteria. Anyone can develop Legionnaires' disease, but
the elderly, smokers, alcoholics and those with cancer, diabetes or
chronic respiratory or kidney disease are at more risk.
The Health and Safety Executive in the UK Advises conducting
a complete risk assessment of the hot and cold water systems
and ensure adequate measures are in place to control the risks.
Recognised measures include but are not limited to the following:
•
Cold water should be stored and distributed below 20ºC
•
Hot water cylinders should store water at 60
•
Hot water should be distributed at 50
thermostatic mixer valves need to be fi tted as close as possible
to outlets)
•
Regular temperature checks of hot water tanks (at least every
month)
•
Regular temperature checks of cold water tanks (if used, at
least every 6 months)
•
Regular temperature checks of outlets closest and furthest
from the hot water tank
•
Flush out infrequently used outlets at least weekly and clean
and de-scale shower heads every 3 months
•
Inspect the DHW tank for signs of debris during the annual
service. Clean as necessary.
•
Design water systems to minimise Legionella growth, by:
•
Keeping pipe work as short as possible
•
Avoid dead legs/dead ends in pipe work
•
Keep water turning over regularly. Fit an anti-legionella
valve on the expansion vessel to maintain circulation
around the vessel
•
Insulating circulation pipes and any cold water tanks
Other methods to control legionella include copper and silver
ionisation and biocide treatments. Consult a water treatment expert
for advice on these measures.
This heater has been designed to minimise the formation of Le-
gionella bacteria. The pumped tank charging process ensures that
the water at the bottom of the tank reaches the same temperature
as in the rest of the tank and all of the water is circulated, with
no stagnation possible. A hatch in the main tank can be used for
inspection and cleaning. Only metals listed in 4MSI are used in this
heater, and the heater has a Kiwa Regulation 4 approval pending.
60
C or higher
o
C or higher (any
o
MAXXfl o EVO Lite
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