Effectiveness In Combating Legionella - andrews ECOflo EC230/600 Installation Manual, Operation And Maintenance Manual

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GENERAL AND SAFETY INFORMATION • SECTION 1
EFFECTIVENESS IN COMBATING
LEGIONELLA
Water systems in buildings have been associated with
outbreaks of Legionnaires' Disease, particularly in health
care facilities where occupants are significantly more
susceptible to infection.
In recognition of the risks in hospitals, a Code of Practice
for the Control of Legionella in Health Care premises has
been issued by the Department of Health (1991). Codes
of Practice applicable to other premises have been
published by other organisations, principally the Health
and Safety Executive (HS)(G70) and the Chartered
Institute of Building Services Engineers (CIBSE, TM13).
All Codes of Practice draw attention to the design and
operation of water systems with reference to avoidance of
factors that favour colonisation by Legionella bacteria.
These factors include stagnation, lukewarm conditions
(20°C to 45°C) and the accumulation of debris, scale and
corrosion in the base of tanks and calorifiers.
Andrews Water Heaters have commissioned an
independent evaluation of their products to investigate
their resistance to build-up of Legionella bacteria.
Experiments were conducted to determine whether,
following a substantial challenge by legionella
pneumophilia. After overnight and stagnation, the system
was rendered free from viable recoverable legionella. It
was found that at 61°C, following a challenge of
approximately 107 organisms per litre, within one hour,
more than 99.999% of organisms had been killed. After a
subsequent stagnation period, sampling did not reveal
any residual contamination. The design of the base of the
water heater precludes legionella colonisation, even after
build-up of debris. The burner positioning ensures that
the water at the bottom of the heater reaches the same,
or higher, temperatures as in the rest of the heater.
Based on data obtained through experiment, the
Andrews Water Heater can be described as legionella
resistant as it is considered unlikely that, at the
temperature tested, the organism would colonise the
water heater and present a possible health risk.